JP3977306B2 - Image processing apparatus and image processing method - Google Patents

Description

  The present invention relates to a technology for synthesizing and outputting a copy-suppressed copy-forgery-inhibited pattern on the background of a document for the purpose of suppressing illegal forgery and information leakage due to copying of an important document.

  Some receipts, securities, and certificates have a special pattern printed on the background that makes characters and images appear when copied so that they are not easily copied. This special pattern is generally referred to as “counterfeit deterrence pattern”, and implements a mechanism that prevents the original from being easily duplicated by copying, realizing a psychologically effective effect of inhibiting copying of the original.

  This counterfeit copy-forgery-inhibited pattern is composed of two regions having the same density: a region where dots remain after copying and a region where dots disappear after copying. These two regions have almost the same density. Macroscopically, it cannot be seen that characters and images such as “copy” are hidden, but they have different characteristics in terms of micro. This hidden character or image is referred to as a “latent image”.

  For example, an area in which dots remain after copying (called a latent image portion) is composed of clustered dots in which each dot is concentrated, and an area in which dots disappear after copying (called a background portion) is a dot in which each dot is dispersed. By configuring, it is possible to create two regions having such almost the same concentration and different characteristics.

  Concentrated dots and dispersed dots can be generated in image processing by halftone processing using halftone dots having different numbers of lines or dither processing using dither matrices having different characteristics.

  In this halftone processing, it is preferable to use a halftone dot with a low line number to obtain a concentrated dot arrangement, and use a halftone dot with a high line number to obtain a dispersed dot arrangement.

  In dither processing using a dither matrix, a dot concentrated dither matrix may be used to obtain a concentrated dot arrangement, and a dot dispersed dither matrix may be used to obtain a dispersed dot arrangement.

  Therefore, when generating a copy-forgery-inhibited pattern image using the above-described halftone processing, a halftone processing with a low number of lines is suitable for the latent image portion, and a halftone processing with a high number of lines is suitable for the background portion, and dither processing is used. When the copy-forgery-inhibited pattern image is generated, dither processing using a dot concentration type dither matrix is suitable for the latent image portion, and dither processing using a dot dispersion type dither matrix is suitable for the background portion.

  In general, a copying machine has a limit of image reproducibility depending on an input resolution for reading minute dots of a copied document and an output resolution for reproducing minute dots. Therefore, if there are small dots in the document that exceed the limit of the image reproduction capability of the copier, the small dots cannot be completely reproduced in the copy, and the isolated small dots will fall out. End up.

  In other words, if the background of the forgery-inhibited background pattern is created to exceed the limit of dots that can be reproduced by a copier, large dots (concentrated dots) in the forgery-inhibited background pattern can be reproduced by copying, but small dots (distributed) (Dot) cannot be reproduced, and a hidden image (latent image) appears. Even if the dots dispersed by copying do not completely disappear, a hidden image (latent image) also appears when there is a clear density difference after copying compared to concentrated dots.

  In addition, a technique called “camouflage” that makes it difficult to distinguish hidden characters and images (latent images) is well known for forgery-suppressing background patterns. This camouflage technology is a method of arranging a pattern with a different density from the latent image portion or background portion over the entire forgery-inhibited tint block image. At first glance, the density of the latent image portion or background portion is different from that of the latent image portion or background portion. The camouflage pattern is conspicuous and the latent image is more inconspicuous.

  In addition, compared with a forgery-inhibiting tint block without a camouflage pattern, a forgery-inhibiting tint block having a camouflage pattern has an effect of giving a decorative impression to a printed matter. In this camouflage pattern, it is desirable that the dots inside the camouflage pattern disappear as much as possible after copying so that the latent image can be easily identified after copying. In the simplest implementation, camouflage can be achieved by not hitting dots at locations corresponding to camouflage patterns.

  The above is the outline of the counterfeit copy-forgery pattern.

  Conventionally, printing paper manufacturers have previously printed a copy-forgery-inhibited pattern including characters and images (latent images) such as “copy” on a dedicated paper and sold it as copy-preventing paper. Then, government offices and companies purchased the copy-preventing paper and printed the document whose originality is to be guaranteed on the copy-preventing paper, thereby inhibiting the copying of the printed matter.

  The above-mentioned copy prevention paper is created by printing paper manufacturers by preprinting the background pattern on the special paper, so the cost of using the special paper, the cost caused by preparing more than the required number of preprinted paper, etc. There were disadvantages.

  On the other hand, in recent years, a technology for creating a forgery-inhibited tint block image in software and outputting a document in which the forgery-inhibited tint block image is placed in the background with a laser printer (here, “on-demand tint block output method using a printer”) (Refer to Patent Document 1, for example).

  In this on-demand copy-forgery-inhibited pattern output method using a printer, since a document having a forgery-inhibited background pattern arranged on the background can be printed using plain paper, a document having the forgery-inhibited background pattern arranged on the background is printed when necessary. be able to. Therefore, it is not necessary to prepare copy prevention paper more than necessary as in the prior art. That is, the on-demand copy-forgery-inhibited pattern output method using a printer can greatly reduce the cost of paper compared to a conventional document copy suppression method using copy-preventing paper.

  In addition, users of conventional copy protection paper can only use hidden characters and images (latent images) prepared in advance, or hidden characters and images (latent images) ordered on a custom-made basis.

  However, with the on-demand copy-forgery-inhibited pattern output method using a printer, a user can generate a copy-forgery-inhibited pattern image including any hidden characters and images (latent images) by software processing for each printing and print it on-demand with the printer. There is an advantage that customized characters and images (latent images) can be freely customized.

  If you take advantage of the ability to select this latent image on demand, you can use not only the company logos and non-copying characters that are conventionally used as images and characters to be embedded as latent images, but also serial numbers that identify output printers, for example. And IP address, computer name and IP address for identifying the computer that issued the print command, user name and login name for identifying the user who issued the print command, and print job for identifying when and who performed the printing process Various information such as a number, printing date / time, printing location, and file name of the electronic document can be selected.

As a result, the on-demand copy-forgery-inhibited pattern output method using a printer can realize a more advanced tracking function that could not be realized with conventional copy-prevention paper.
JP 2001-197297 A

  In the on-demand background pattern output method by the printer described above, the density of the latent image portion and the background portion vary depending on the printer engine characteristics, the printing environment (temperature and humidity), the output paper (media), and the like. is expected.

  Therefore, in order to place a copy-forgery-inhibited pattern image on the background of a document whose copy is to be suppressed and to realize the copy-suppressing effect, first, the print density of the latent image portion and the background portion of the copy-forgery-inhibited pattern image to be combined with the document whose copy is to be suppressed is almost equal. It is necessary to appropriately adjust the density of the latent image portion and the background portion of the tint block image so that the latent image portion becomes equal after copying. In this specification, a parameter that determines the print density of the background portion and the latent image portion of the copy-forgery-inhibited pattern image when generating the copy-forgery-inhibited pattern image is referred to as a “background pattern density parameter”. The components of the “background pattern density parameter” will be described in detail later.

  As a method for searching for the tint block density parameter, a test print is executed before synthesizing the document and tint block image, and the density of the latent image portion and the background portion becomes substantially equal at the time of printing. A general method is to visually find a tint block image in which a latent image emerges, and to determine the tint block density parameter used when generating the tint block image as an optimum tint block parameter. Thereafter, a copy-forgery-inhibited pattern image is generated based on the determined optimum copy-forgery-inhibited pattern density parameter.

  However, there are printers in which the gradation reproduction characteristics of the latent image portion and the background portion are greatly different due to printer engine characteristics and individual differences. There is also a difference in gradation reproduction characteristics between the latent image portion and the background portion due to the difference in the type of output paper. For example, in the case of an ink jet printer, the gradation reproduction characteristics of the latent image portion and the background portion may be different due to dot bleeding depending on the characteristics of the output paper. There are also printers with large density fluctuations due to the printing environment and durability. For example, in the case of a laser printer, the electric field distribution of the photosensitive drum is easily affected by humidity and temperature, and when the electric field distribution becomes gentler, it is distributed. The reproduction of dots and isolated dots tends to be unstable.

  In general, in trial printing of a tint block image, one or both of the latent image portion and the background portion is gradually changed in density so that the difference in density between the finally obtained latent image portion and the background portion is difficult to visually recognize. , One or both of the concentrations must be matched.

  When the gradation reproduction characteristics of the latent image portion and the background portion depending on the printer engine characteristics, output paper, and the like are determined, this can be dealt with by determining the optimum tint block density parameter according to the model and paper.

  However, when searching for the optimum tint block density parameter, taking into account the latent image density and background density changes that depend on the printing environment and durability, the density fluctuation range resulting from changes in the printing environment and durability. Is also included in the assumption, a relatively wide range from low to high density is combined with a large number of tint block density parameters with a slight change width so that the difference in density between the latent image area and the background area cannot be visually discriminated. Must be prepared and test printed to find the optimal tint block density parameter.

  In the case of a printer having a large density fluctuation range that depends on changes in the printing environment and durability, the combination of the tint block density parameters necessary for finding the optimum tint block image inevitably increases according to the density fluctuation range. Although it is possible to perform test printing for all the tint block density parameters, a large number of papers are required for the test printing.

  Therefore, the latent image part depends on the printer environment and durability, the printer whose engine gradation characteristics and the gradation reproduction characteristics of the background part depending on the engine characteristics and output paper are unknown (the printer of the old generation and the future printer), etc. Since it is difficult to obtain an optimal copy-forgery-inhibited pattern image with a single trial print, the printer that can output a copy-forgery-inhibited pattern image is limited in printers with large changes in image density and background density. It was.

  However, if there is a means for efficiently finding the optimum tint block density parameter, and if the means for printing the tint block is provided to the user who prints the tint block using the forgery-preventing tint block in the on-demand tint pattern output method by the printer, the on-demand tint pattern by the printer There is an advantage that the output method can be universally applied to more printers.

The present invention is an image processing apparatus that generates a tint block image patch including a latent image portion and a background portion, and changes at least one of the density parameter of the latent image portion and the density parameter of the background portion. At least one of the first tint block image patch group output means for outputting the first tint block image patch group generated at step 1 and the first tint block image patch group output by the first tint block image patch group output means. An input unit that inputs information indicating one copy-forgery-inhibited pattern image patch based on an instruction from the user, and a second copy-forgery-inhibited pattern based on the density parameter used to generate the copy-forgery-inhibited pattern image patch indicated by the information input by the input unit. second copy-forgery-inhibited pattern image to be output and the second pattern image patch group generating means for generating an image patch group, the second copy-forgery-inhibited pattern image patch group generated by the second pattern image patch group generator A second input unit that inputs information indicating one copy-forgery-inhibited pattern image patch of the second copy-forgery-inhibited pattern image patch group output by the patch group output unit and the second copy-forgery-inhibited pattern image patch group output unit based on an instruction from the user; The image forming apparatus includes: an input unit; and a tint block image generation unit configured to generate a tint block image based on a density parameter used for generating the tint block image patch indicated by the information input by the second input unit .

The present invention is also an image processing method for generating a tint block image patch including a latent image portion and a background portion, and changes at least one of the density parameter of the latent image portion and the density parameter of the background portion. A first tint block image patch group output step for outputting the first tint block image patch group generated by the step, and a first tint block image patch group output in the first tint block image patch group output step Based on an input step for inputting information indicating at least one copy-forgery-inhibited pattern image patch based on an instruction from the user, and a second parameter based on the density parameter used for generating the copy-forgery-inhibited pattern image patch indicated by the information input in the input step. of the second pattern image patch group generating step of generating a background pattern image patch group, a second outputting a second copy-forgery-inhibited pattern image patch group generated by the second pattern image patch group generation step First, information indicating one copy-forgery-inhibited pattern image patch in the second copy-forgery-inhibited pattern image patch group output step and the second copy-forgery-inhibited pattern image patch output step is input based on an instruction from the user. And a copy-forgery-inhibited pattern image generation step for generating a copy-forgery-inhibited pattern image based on the density parameter used for generating the copy-forgery-inhibited pattern image patch indicated by the information input in the second input process. To do.

  According to the present invention, in the on-demand copy-forgery-inhibited pattern output method by the printer, the difference in the gradation reproduction characteristics of the latent image portion and the background portion due to the engine characteristics of the printer, the characteristics of the output paper, individual differences, etc., the printing environment and durability Even when the resulting density fluctuation is large, the latent image portion and the background portion are optimally printed to generate a copy-forgery-inhibited pattern image in which the print density of the latent image portion and the background portion approximates and the background portion disappears after copying. The tint block density parameter for determining the density can be determined efficiently.

  The best mode for carrying out the invention will be described below in detail with reference to the drawings. In this embodiment, the image corresponding to the background portion is designed so that dots are discretely arranged using a dot dispersion type dither matrix, and the image corresponding to the latent image portion is a dot concentration type dither matrix. It is assumed that the dots are designed to be arranged in a concentrated manner.

  Hereinafter, the dither matrix used for generating the background image is referred to as a background dither matrix, and the dither matrix used for generating the latent image portion is referred to as a latent image dither matrix.

  The dither method is a method in which a multi-value input image signal is compared with a threshold value calculated according to a certain rule, and a binary image is output based on the magnitude relationship. The dither matrix is a threshold matrix in which thresholds for binarizing an input image signal by the dither method are two-dimensionally arranged.

  A binary image (threshold pattern) is obtained by binarizing the pixel value of the input image signal with the threshold value of the corresponding dither matrix, but the obtained binary image has a gradation of the dither matrix of the input image signal. If it is less than the threshold value, one bit (for example, 1) is assigned to the pixel value, and if it is greater than or equal to the threshold value, the other bit (for example, 0) is assigned.

  In this embodiment, the binary image constituting the background and the binary image constituting the latent image portion are respectively appropriate so that the background portion and the latent image portion have substantially the same density when printed on paper using a printer. Assume that an input image signal is input and generated in advance by a dither method.

  A background threshold pattern and a method for generating a latent image threshold pattern, which will cause the background portion and the latent image portion to have substantially the same density when printed on paper using a printer, will be described in detail later.

  In the following description, the binary image constituting the background portion is referred to as a background threshold pattern, and the binary image constituting the latent image portion is referred to as a latent image threshold pattern.

  In this embodiment, a combination of a background threshold pattern and a latent image threshold pattern, which is a pattern (binary image) constituting the background portion and the latent image portion so that the densities of the background portion and the latent image portion are equal at the time of printing, is previously set. A background threshold pattern, a latent image threshold pattern, a latent image background area designation image that is a binary image that designates a latent image portion and a background portion, and a camouflage area designation image that is a binary image that designates a camouflage area. Is used to generate a copy-forgery-inhibited pattern image at a high speed and with a reduced amount of memory.

  The background threshold pattern and the latent image threshold pattern are parameters that determine the density of the background portion and latent image portion of the tint block image when printing, and are specific components of the “background pattern density parameter”.

  In addition, by performing a logical operation of dot on / off for the copy-forgery-inhibited pattern image in units of pixels and generating a copy-forgery-inhibited pattern image, the amount of memory required for generating the copy-forgery-inhibited pattern image is greatly reduced. .

  FIG. 1 is a block diagram illustrating internal processing of the tint block composition printing apparatus according to the first embodiment. The tint block composition printing apparatus includes a tint block image generation unit 101, a composition unit 102, a print data processing unit 103, and a printing unit 104.

  First, an input background image 111, color information 112, processing area information 113, latent image threshold pattern 114, background threshold pattern 115, latent image background area designation image 116, and camouflage area designation image 117 are input to the tint block image generation unit 101. Then, the tint block image 118 is generated and output. The copy-forgery-inhibited pattern image generation unit 101 performs image processing on the input background image 111 according to a predetermined rule, and generates a copy-forgery-inhibited pattern image 118. The input background image 111 may be a multi-value image or a binary image. Further, the processing area information 113 is information indicating an area in the input image information where the background pattern embedding process is performed.

  The latent image background area designation image 115 is an image for designating a latent image portion and a background portion, and is composed of one pixel and one bit. One bit (for example, 1) of the latent image background area designation image 115 represents a latent image portion, and the other bit (for example, 0) represents a background portion. The camouflage area designating image 117 is an image for designating an area where the density is to be reduced in order to have a camouflage effect, and is composed of 1 bit per pixel as in the latent image background area designating image 115. One bit (for example, 1) of the camouflage area designation image 117 indicates that it is not a camouflage area, and the other bit (for example, 0) indicates that it is a camouflage area whose density is lower than the surrounding area.

  FIG. 10 is a diagram illustrating an example of the latent image background area designation image 115 and the camouflage area designation image 117. In FIG. 10, reference numeral 1001 denotes an example of the latent image background area designation image 115. Reference numeral 1002 denotes an example of a camouflage area designation image 117.

  As described above, the background threshold pattern 116 and the latent image threshold pattern 114 are subjected to threshold processing on appropriate image signals with the threshold values of the background dither matrix and the latent image dither matrix, respectively, so that they are output as equal densities at the time of print output. Has been generated.

  FIG. 11 is a diagram illustrating an example of the latent image threshold pattern 114 and the background threshold pattern 116. In FIG. 11, reference numeral 1101 denotes a latent image threshold pattern, and 1102 denotes a background threshold pattern.

  Next, the tint block image 118 generated by the tint block image generation unit 101 is output to the synthesis unit 102. A method for generating the copy-forgery-inhibited pattern image 118 will be described in detail later.

  The combining unit 102 combines the input document image 119 and the generated tint block image 118 to generate a tint block composite output document image. Note that, when the copy-forgery-inhibited pattern image 118 is directly used as the copy-forgery-inhibited pattern synthesized output document image regardless of the contents of the input document image 119, it is not necessary to refer to the input document image 119 by the combining unit 102. At this time, the color matching process is executed for each object constituting the copy-forgery-inhibited pattern image 118 and the input document image 119, and then the object constituting the input document image 119 and the copy-forgery-inhibited pattern image 118 are combined to generate a copy-forgery-inhibited pattern output document image. Alternatively, the color matching process may be executed on the copy-forgery-inhibited pattern synthesized output original image in the print data processing unit 103 at the subsequent stage.

  Next, in the print data processing unit 103, a drawing interface of an OS (Operating System) (for example, a Graphic Device Interface (GDI) of a Windows (registered trademark) series that is an OS of Microsoft) or a MacOS series that is an OS of an Apple computer. The copy-forgery-inhibited pattern synthesized output original image synthesized by the synthesizing unit 102 is received as drawing information and is sequentially converted into a print command. At this time, image processing such as color matching processing, RGB-CMYK conversion, and halftone processing is executed as necessary. Then, the print data processing unit 103 uses a data format (for example, a data format described in a page description language or a data format developed in a print bitmap) that can be interpreted by the printing unit 104 as the copy-forgery-inhibited pattern output original image data. The data is sent to the subsequent printing unit 104.

  The printing unit 104 prints out the tint block composition output document according to the input tint block synthesis output document image data information. Here, the case of a laser beam printer will be described as an example. The printing unit 104 includes a printer controller and a printer engine (not shown). The printer controller includes a print information control unit, a page memory, an output control unit, and the like. The print information control unit analyzes the page description language (PDL) sent from the print data processing unit 103 and develops corresponding patterns for drawing and printing commands in the page memory.

  If necessary, image processing such as RGB-CMYK conversion and halftone processing is also executed. If it is determined that the print format is not the data format described in the page description language, the image data is expanded as it is in the page memory.

  The output control unit converts the contents of the page memory into a video signal and outputs it to the printer engine. The printer engine includes, for example, a recording medium conveyance mechanism, a semiconductor laser unit, a photosensitive drum, a developing unit, a fixing unit, a drum cloning unit, a separation unit, and the like, and performs printing by a known electrophotographic process.

  When the copy-forgery-inhibited pattern image generation unit 101 creates a copy-forgery-inhibited pattern image with the intention that each pixel is printed and output only in the primary colors (cyan, yellow, magenta, and black) of the printer, It is not desirable that each pixel expressed assuming output in colors (cyan, yellow, magenta, black) is printed with a plurality of different colors of ink or toner. Accordingly, the print data processing unit 103 and the printing unit 104 print a pixel value of one pixel for pixel values (for example, cyan, magenta, yellow, and black) corresponding to the copy-forgery-inhibited pattern image in the copy-forgery-inhibited pattern output document image. It is sometimes desirable to set the colors so that they are simultaneously expressed with a plurality of different colors of ink and toner and do not mix.

  Specifically, it is preferable to introduce a setting in which each pixel is always printed with a single color ink or toner even after color conversion processing such as color matching is passed and halftone processing is executed. However, this is not the case when one pixel of the copy-forgery-inhibited pattern image is expressed by light ink, dark ink, large ink dots, or small ink dots of the same color on an inkjet printer. In addition, as a color variation of the tint block image, it is possible to generate a tint block image that looks green at first glance by arranging cyan pixels and yellow pixels in a balanced manner. If the primary color of the printer (cyan, yellow, magenta, black) is used, it is desirable that one pixel of the copy-forgery-inhibited pattern image is output accurately only with the corresponding cyan or yellow toner or ink.

  However, it is possible to generate an image that realizes the effect of the tint block even if one pixel of the tint block image is not printed out only with the primary colors (cyan, yellow, magenta, black) of the printer. Even if one pixel of a copy-forgery-inhibited pattern image is expressed by a plurality of inks or toners of different colors, it can be used as a forgery-proof copy-forgery-inhibited pattern if a latent image remains after copying.

  In the embodiment, the copy-forgery-inhibited pattern image, the input document image, the copy-forgery-inhibited pattern output document image, and the copy-forgery-inhibited pattern output document image data are all digital data, and the copy-forgery-inhibited pattern output document image represents an image printed on paper.

  Next, the internal processing of the forgery-inhibited tint block generation device will be described with reference to FIG.

  FIG. 2 is a flowchart illustrating an internal processing procedure of the tint block image generation unit 101 according to the first embodiment. First, a tint block image generation process is started in step S201 through a user interface or the like. In step S202, the input background image 111, the background threshold pattern 116, the latent image threshold pattern 114, the latent image background area designation image 115, and the camouflage area designation image 117 are read.

  Next, in step S203, an initial pixel for generating a tint block image is determined. For example, when the entire input image is subjected to image processing in the order of raster scanning from the upper left to the lower right, and changed to a tint block image, the upper left is set as the initial position.

  Next, in step S204, the background threshold pattern 116, the latent image threshold pattern 114, the latent image background area designation image 115, and the camouflage image 117 are arranged on the tile from the upper left of the input background image 111, and are processing targets. The following equation (1) is calculated for the pixels of the input background image 111, and it is determined whether or not to write pixel values corresponding to the dots at the time of printing. At this time, the pixel value corresponds to the input color information 112.

Here, the definition of the component of Formula (1) is shown below.
nCamouflage: 0 if the pixel is a camouflage area in the camouflage area designation image, 1 otherwise
nSmallDotOn: 1 if the pixel value of the background threshold pattern is black, 0 if white
nLargeDotOn: 1 if the pixel value of the latent image threshold pattern is black, 0 if white
nHiddenMark: 1 if a pixel corresponding to a latent image portion in a latent image background area designation image, 0 if a pixel corresponding to a background portion
/ nHiddenMark: Denial of nHiddenMark. 0 in the latent image portion and 1 in the background portion.

  At this time, it may be determined whether or not to write a pixel value corresponding to a dot at the time of printing while referring to the pixel value of the input background image. In this case, it is preferable to multiply an item (nBackground) obtained by referring to the input background image on the right side of Expression (1). This nBackground is 1 if the input background image has a specific pixel value (white background area), and 0 otherwise.

  Moreover, it is not necessary to calculate using all the elements of Formula (1) for each pixel to be processed. As described below, the processing speed can be increased by eliminating unnecessary calculations.

  For example, if nHiddenMark = 1, / nHiddenMark = 0, and if nHiddenMark = 0, / nHiddenMark = 1. Therefore, if nHiddenMark = 1, the value of equation (2) is the value of nLargeDotOn, and if nHiddenMark = 0, the value of equation (2) is preferably the value of nSmallDotOn.

  Further, the value of nCamouflage is an integration over the whole. If nCamouflage = 0, nWriteDotOn = 0. Therefore, in the case of nCamouflage = 0, the calculation of equation (2) after nCamouflage may be omitted.

Further, in the generated tint block image, an image having a size of the least common multiple of the vertical and horizontal lengths of the background threshold pattern 116, the latent image threshold pattern 114, the latent image background area specifying image 115, and the camouflage area specifying image 117 is the minimum of repetition. Therefore, when the copy-forgery-inhibited pattern image generation unit 101 generates only a part of the copy-forgery-inhibited pattern image, which is the smallest repetitive unit, and repeatedly arranges a part of the copy-forgery-inhibited pattern image in the size of the input background image, the copy-forgery-inhibited pattern image 118 The processing time required for generating can be reduced.
Next, in step S205, the calculation result (value of nWriteDotOn) in step S204 is determined. If nWriteDotOn = 1, the process proceeds to step S206. If nWriteDotOn = 0, the process proceeds to step S207.

  In step S206, a process of writing pixel values corresponding to dots at the time of printing is performed. The value of the pixel value can be changed depending on the color of the tint block image 118. When it is desired to create a black background pattern, the processing target pixel of the input background image 111 is set to black. In addition, a color tint block image 118 can be created by setting cyan, magenta, and yellow according to the color of the toner or ink of the printer.

When the input background image 111 is 1 to several bits of image data per pixel, the pixel value may be expressed using an index color. The index color is a method of expressing image data. Color information that frequently appears in the target color image is set in the table of contents (for example, index 0 is white, index 1 is cyan, etc.), and the value of each pixel is color information. (For example, the first pixel value is represented by the index 1 value, the second pixel value is represented by the index 2 value,...).
In step S207, it is determined whether all pixels in the processing target area of the input background image 111 have been processed. If all the pixels in the processing target area of the input background image 111 have not been processed, the process proceeds to step S208, an unprocessed pixel is selected, and the processes of steps S204 to S206 are executed again. If processing for all pixels in the processing target area of the input background image 111 has been completed, the process proceeds to step S209, and the image processing in the tint block image generation unit 101 is terminated. Through the above-described processing, a tint block image 118 obtained by performing image processing on the input background image 111 can be generated.

  Next, a method for arranging dots in the latent image portion and the background portion in the embodiment will be described. In the embodiment, a case where a latent image portion is generated based on a dot concentration type dither matrix and a background portion is generated based on a dot dispersion type dither matrix will be described. A representative example of the dot concentration type dither matrix used when generating the latent image portion is a spiral dither matrix.

  FIG. 3 is a diagram illustrating an example of a 4 × 4 spiral dither matrix. The threshold values of the 4 × 4 spiral dither matrix are arranged in a spiral shape with numerical values increasing from the center.

  FIG. 4 is a diagram showing a threshold pattern (dot arrangement) obtained by performing threshold processing on a predetermined input image signal using the 4 × 4 spiral dither matrix of FIG. 4, 401, 402, and 403 indicate threshold patterns obtained by performing threshold processing on the input image signals 3, 6, and 9, respectively, using the dither matrix of FIG. The threshold pattern (dot arrangement) obtained here is a pattern in which each dot is arranged in a concentrated manner.

  On the other hand, a Bayer type dither matrix is a representative example of the dot dispersion type dither matrix that constitutes the background portion. The Bayer type N × N dither matrix is expressed by the following equation.

However, N is the power of 2, U _N is the N × N matrix of each element 1.
FIG. 5 is a diagram illustrating an example of a 4 × 4 Bayer-type dither matrix. A threshold pattern generated by dithering an arbitrary input image signal with a Bayer-type dither matrix is designed so that each dot is arranged in a distributed manner.

  FIG. 6 is a diagram illustrating a threshold pattern (dot arrangement) obtained by performing threshold processing on a predetermined input image signal using the 4 × 4 Bayer-type dither matrix of FIG. 6, reference numerals 601, 602, and 603 denote threshold patterns obtained by performing threshold processing on the input image signals 2, 4, and 5 using the dither matrix shown in FIG. The threshold pattern (dot arrangement) obtained here is a pattern in which each dot is arranged dispersedly. In the Bayer-type dither matrix, the elements of the threshold matrix are sequentially arranged at positions where they do not touch each other as much as possible, and the threshold pattern takes an isolated grid-like dot arrangement. In the Bayer type dither, when the size of the dither matrix increases, periodic textures due to the matrix may be conspicuous, but there is an advantage that a periodic and beautiful pattern can be obtained at a specific gradation.

  In the present embodiment, the case where a Bayer type dither matrix is used as a background dither matrix will be mainly described below, but the dither matrix is not limited to the Bayer type dither matrix. Other dot dispersion type dither matrices may be used.

  For example, a blue noise mask is an example of a dot dispersion type dither matrix used for the background. In this blue noise mask, all threshold patterns in an arbitrary gradation have blue noise characteristics, and the distribution of black pixels forming the threshold pattern is random but highly uniform, and the graininess is not conspicuous. The blue noise characteristic means that the output pattern of points when set to an arbitrary gradation is locally aperiodic and isotropic and has low frequency components. . The threshold pattern obtained from the blue noise mask has advantages in that a visually preferable output pattern can be obtained, for example, by preventing the occurrence of moire and making paper feed unevenness inconspicuous.

  Further, a dot dispersion type dither matrix may be used that is not a blue noise mask but has a periodic (or pseudo-periodic) threshold pattern at a specific or arbitrary gradation, is anisotropic, and has low low frequency components. . Further, although not a method using a threshold pattern, in the present embodiment, a configuration of a background portion using an error diffusion method is also possible. When the background threshold pattern is generated using the Bayer-type dither matrix or the blue noise mask already described, the value of nSmallDotOn in Equation (1) can be read by referring to the background threshold pattern. On the other hand, when the error diffusion method is used, the tone corresponding to the background density for each pixel and the sum of the error propagated from the surrounding pixels are compared with a predetermined threshold value, and the dot On in the pixel to be processed is turned on. / Off is determined and used as the value of nSmallDotOn. At this time, an error caused by dot On / Off is weighted and distributed to neighboring pixels. The pixel value of the unprocessed pixel is the sum of the original input pixel value corresponding to the background density and the distributed error. As in the case of the background threshold pattern, it is assumed that the gradation corresponding to the background density is prepared in advance. The error diffusion method has a demerit that takes a long time, but has an advantage that an image with good visual characteristics in which dots are uniformly dispersed can be obtained. Since the error diffusion method is already well known, detailed description thereof is omitted in this embodiment. Similarly, a method obtained by improving the error diffusion method is also applicable.

  Further, the threshold pattern for each gradation may not be generated based on the dither matrix. A background threshold pattern and a latent image threshold pattern may be independently generated for each gradation. In this case, there is also an advantage that threshold patterns with good image quality can be collected for each gradation.

  FIG. 7 is a diagram for comparing the area ratio of black pixels in the background threshold pattern and the latent image threshold pattern. As shown in FIG. 7, the vertical and horizontal sizes of the background dither matrix are X_S and Y_S, the gradation of the input image signal is T_S, and the vertical and horizontal sizes of the latent image dither matrix are X_L and Y_L. Let T_L be the gradation of the input image signal.

  At that time, the ratio of black pixels in the background threshold pattern is P_S = T_S / (X_S * Y_S), and the ratio of black pixels in the latent image threshold pattern is P_L = T_L / (X_L * Y_L).

  FIG. 8 is a diagram illustrating the relationship between the area ratio of black pixels of a threshold pattern obtained by performing threshold processing on an input image signal with a dither matrix and the density when the threshold pattern is printed. In the dither processing, the area ratio of the black pixels changes according to the gradation of the input image signal, so the horizontal axis in FIG. 8 may be regarded as the gradation of the input image signal.

  Here, the dither matrix (background threshold pattern) of the background portion and the dither matrix (latent image threshold pattern) of the latent image portion do not have to have the same side size, and may be different sizes. For example, when the gradation characteristics of the background dither matrix and the latent image dither matrix are the same as those shown in 801, the horizontal axis represents the dither matrix of the background portion and the latent image portion regardless of the size of the dither matrix. If the values (area ratio of black pixels) are substantially equal, that is, if the values of the gradations T_S and T_L of the input image signal such that P_S and P_L are substantially equal, then the background threshold pattern and the latent image threshold pattern It is possible to generate a copy-forgery-inhibited pattern image in which the densities are substantially equal and the latent image is not noticeable.

  However, actually, the gradation characteristics of the background dither matrix and the latent image dither matrix are not always the same due to the characteristics of the printer.

  For example, it is assumed that the gradation characteristic of the latent image dither matrix is represented by a gentle S-shaped curve as indicated by 802, and the gradation characteristic of the background dither matrix is represented by a steep S-shaped curve as indicated by 803. In such a case, the density of the background portion and the latent image portion at the time of printing is not the same even if the area ratio of the black pixels of the background threshold pattern and the latent image threshold pattern is set to be approximately equal.

  By appropriately adjusting the input image signal for the dither matrix of one or both of the background portion and the latent image portion, the density at the time of the other printing can be made as close as possible.

  If the number of gradations that can be expressed by the background dither matrix or the latent image dither matrix is large, the density of the background portion or latent image portion can be finely adjusted by adjusting the gradation of the input image signal.

  When the latent image dither matrix is a dot-concentrated dither matrix as shown in FIG. 3, when the gradation of the input image signal is below a certain level, it becomes close to an isolated dot, and the latent image portion tends to disappear during copying. On the other hand, when the gradation of the input image signal exceeds a certain level, the dots are concentrated and the clustered dots constituting the latent image are easily recognized clearly by human eyes.

  Therefore, in the latent image dither matrix, it is better to keep the gradation of the possible input image signal within a certain range. In the latent image dither matrix as shown in FIG. 3, even if the size of the dither matrix changes, if the gradation of the input image signal is the same, substantially the same concentrated dot arrangement can be obtained. Therefore, it is possible to change the density per unit area by keeping the gradation of the input image signal with respect to the latent image dither matrix constant and changing the size of the dither matrix.

  On the other hand, when the background dither matrix is a dot-dispersed dither matrix as shown in FIG. 8, the density can be changed while hitting dots uniformly throughout by changing the gradation of the input image signal. Therefore, it can be said that the background dither matrix having a wider gradation (that is, the dither matrix having a larger size) is superior in adjusting the density of the background portion.

  Note that when outputting a forgery-inhibited tint block with a printer, an adjustment function for adjusting the density variation of the printer is required, which will be described in detail later.

  FIG. 9 is a schematic diagram showing how a tint block image is generated by using the tint block composition printing apparatus of FIG. In FIG. 9, reference numerals 901, 902, and 903 denote a latent image threshold pattern, a background threshold pattern, and a latent image background area designation image, respectively, and 904 denotes a copy-forgery-inhibited pattern image generated based on Expression (1). It should be noted that no camouflage pattern was introduced at the generation stage 904.

  In the copy-forgery-inhibited pattern image 904, as shown in a circled area 910, a cluster of dots in which the latent image threshold pattern and the background threshold pattern are merged at the portion where the latent image and the background of the latent image background area designation image 903 are switched. Has been generated. This cluster of dots tends to occur when the latent image and background switching of the latent image background area designation image 903 and the size of the latent image threshold pattern are not synchronized. In addition, since the cluster of dots appears concentratedly only at the portion where the latent image and the background of the latent image / background area designation image are switched, the outline of the latent image is conspicuous, and there is a demerit that the effect of the counterfeit suppression background pattern is diminished.

  Therefore, in order to generate a high-quality copy-forgery-inhibited pattern image, there is a process of preventing dot clumps from occurring when the latent image and background image of the latent image background area designation image are switched.

  In the embodiment, hereinafter, a process for preventing dot clumps from occurring when a latent image and a background of a latent image / background area designation image are switched is referred to as a “boundary process”. As an example of this boundary processing, the repetitive arrangement corresponding to the center of the repetitively arranged latent image threshold pattern (centering on the pixel moved from the upper left by the amount of pixels obtained by discarding half of one side of the latent image threshold pattern) is performed. There is a method in which only the pixel value of the latent image background area designation image is read to obtain the HiddenMarkLattice value, and the pixels belonging to the same latent image threshold pattern are processed using the same HiddenMarkLattice value. This processing method is expressed as follows:

When this method is used, the latent image threshold pattern is configured with the white background of the latent image threshold pattern around it unless it is at the edge of the image. Therefore, if a white background exists around the black pixels of the latent image threshold pattern, the white background becomes a buffer zone and the black pixels of the latent image threshold pattern do not contact the black pixels of the background threshold pattern, and the latent image background area designation The part where the latent image specified in the image and the background are switched does not stand out.
905 shown in FIG. 9 is a tint block image that has undergone boundary processing. In 905, it can be seen that there is no cluster of dots in which the latent image threshold pattern and the background threshold pattern are merged at the switching portion between the latent image specified in the latent image background area designation image and the background.

  As another example of the boundary processing, there is a method of pre-processing so that the switching between the latent image and the background in the input latent image background area designation image is synchronized with the size of the latent image threshold pattern. In this method, first, a latent image threshold area pattern is repeatedly arranged in the latent image background area designation image, the pixel value of the latent image background area designation image corresponding to the center of the latent image threshold pattern is read, and the subsampled latent image background is obtained. An area designation image is generated. Next, the subsampled latent image background area designation image is newly enlarged so that one pixel becomes an integral multiple of the size of the latent image threshold pattern, and a corrected latent image background area designation image is created. Finally, if a copy-forgery-inhibited pattern image is generated based on the formula (1) for the corrected latent image background area designation image, the copy-forgery-inhibited pattern image can be generated without causing a cluster of dots as shown in 910.

  When the above-described “boundary processing” is added to the tint block generation unit 101, a latent image background area designation image is created by synchronizing the portion of the latent image and background designated in the latent image background area designation image with the size of the latent image threshold pattern. Because it is not necessary to do this, it is convenient for users.

  FIG. 12 is a diagram showing a part of the tint block image generated by the tint block generation unit 101 by the boundary processing. When the copy-forgery-inhibited pattern image shown in FIG. 12 is generated, images 1001 and 1002 shown in FIG. 10 are used as the latent image background area designation image and the camouflage area designation image, respectively. The images 1101 and 1102 shown in FIG. 11 are used. Note that broken lines surrounding the images 1001, 1002, 1101, and 1102 indicate image boundaries and do not exist in the actual image. Since the tint block image in FIG. 12 is subjected to boundary processing, the dot solidification phenomenon does not occur at the boundary between the latent image portion and the background portion, and the latent image portion is difficult to distinguish.

  Next, a description will be given of processing in the combining unit 102 that combines the copy-forgery-inhibited pattern image generated by the copy-forgery-inhibited pattern generation unit 101 and an input document image (for example, a form or a certificate).

  FIG. 13 is a schematic diagram showing a composition process of an input document image and a tint block image. In FIG. 13, reference numeral 1301 denotes text attribute data, 1302 denotes graphic attribute data, and 1303 denotes an image attribute copy-forgery-inhibited pattern image.

  The composition unit 102 superimposes each of the images 1301 to 1303 by software according to the priority order (layer structure) regarding the arrangement using the OS drawing interface, text attribute data, graphic attribute data as indicated by 1304. Then, an image in which the copy-forgery-inhibited pattern image having the image attribute is combined is generated. This processing is almost the same as screen drawing (display drawing) in drawing software, which is a general application of a computer. Note that the composition unit 102 may independently perform image composition processing without depending on the OS drawing interface processing.

  In the example shown in FIG. 13, the copy-forgery-inhibited pattern image 1303 having the image attribute is superimposed as the lowest layer compared to the text attribute data 1301 and the graphic attribute data 1302. For example, in the position where the image attribute copy-forgery-inhibited pattern image 1303 and the text attribute data 1301 overlap, the text attribute data 1301 is preferentially drawn. Accordingly, the copy-forgery-inhibited pattern image is appropriately arranged on the background of the input document image, and the visibility of the text attribute data and the graphic attribute data is not deteriorated.

  In the example shown in FIG. 13, the copy-forgery-inhibited pattern image 1303 is an image having the same size as the input image. It is only necessary to input an input background image having a size corresponding to the area of the image, generate only a copy-forgery-inhibited pattern image matching the input image size, and synthesize it with the input document image by the synthesizer 102. The processing in the tint block image generation unit 101 can be speeded up by the size of the tint block image to be generated.

  The copy-forgery-inhibited pattern output document image output by the combining unit 102 may be data expressed by an OS drawing interface, or may be a bitmap image as a result of combining. Then, the copy-forgery-inhibited pattern combined output original image generated by the combining unit 102 is sent to the print data processing unit 103 at the subsequent stage.

  The print data processing unit 103 receives the copy-forgery-inhibited pattern synthesized output original image synthesized by the synthesis unit 102 as drawing information via the OS drawing interface, and sequentially converts it into a print command. At this time, image processing such as color matching processing, RGB-CMYK conversion, and halftone processing is executed as necessary. Then, the print data processing unit 103 uses a data format (for example, a data format described in a page description language or a data format developed in a print bitmap) that can be interpreted by the printing unit 104 as the copy-forgery-inhibited pattern output original image data. The data is sent to the subsequent printing unit 104.

  The printing unit 104 prints out the tint block composition output document according to the input tint block synthesis output document image data information.

  FIG. 14 is a schematic diagram showing a method for synthesizing a tint block image with an input document image having no layer structure in which various images have already been synthesized. In FIG. 14, reference numeral 1401 denotes an input document image having a layer structure in which various images are already combined, and reference numeral 1402 denotes an area where a tint block image is to be arranged in an area having a specific pixel value (for example, a white background area). Yes.

  It is assumed that the other area of the input document image 1401 does not have a specific pixel value (for example, it is not a white area).

  FIG. 15 is a block diagram showing an internal configuration of a tint block synthesizing printing apparatus for synthesizing a tint block image with an input document image having no layer structure in which various images have already been synthesized. The copy-forgery-inhibited pattern combination printing apparatus shown in FIG. 15 is suitable for combining a copy-forgery-inhibited pattern image with an image (for example, 1401) in which various images have already been combined and have no layer structure.

  As shown in FIG. 15, this tint block composition printing apparatus includes a tint block image composition output document generation unit 1501, a print data processing unit 1502, and a printing unit 1503. First, an input original image, color information, processing area information, latent image threshold pattern, background threshold pattern, latent image background area designation image, and camouflage area designation image are input to the tint block image composition output original generation unit 1501. Generate and output an image composition input document.

  The copy-forgery-inhibited pattern image output document generation unit 1501 detects a region (for example, a white background region) having a specific pixel value in the input document image, combines the copy-forgery-inhibited pattern image only in that region, and outputs a copy-forgery-inhibited pattern image input document image. To do. Specifically, the pixel value corresponding to the copy-forgery-inhibited pattern image is written to the pixels in the input document image by using the following equation obtained by integrating the item (nBackground) that refers to the input document image with respect to Equation (3). Determine whether.

Here, nBackground is set to 1 if the input original image has a specific pixel value (white background area), and is set to 0 otherwise.
Similar to the copy-forgery-inhibited pattern image generation unit 101 shown in FIG. 1, the copy-forgery-inhibited pattern image synthesis output document generation unit 1501 can realize high speed by omitting unnecessary calculations. Since nBackground is an integration over the whole, Equation (3) is calculated only for pixels for which nBackground = 1, and it is determined whether or not to write a pixel value corresponding to the tint block image.

  Except for referring to the pixel value of the input original image, the process is substantially the same as that of the tint block generation unit 101 shown in FIG.

  The tint block composition output document image generated by the tint block image composition output document generation unit 1501 is output to the print data processing unit 1502. The print data processing unit 1502 performs almost the same processing as the print data processing unit 103 in FIG. At this time, the image processing that has passed the color conversion process such as color matching is performed so that the area where the copy-forgery-inhibited pattern image is combined does not become a mixed-color dot because the pixel value of one pixel is expressed by a plurality of different inks or toners during printing Good to do.

  The print data processing unit 1502 further converts the data into a data format that can be interpreted by the printing unit 1504 (for example, a data format described in a page description language or a data format developed in a print bitmap), and outputs a copy-forgery-inhibited pattern output original image data. To the subsequent printing unit 1503.

  Next, the printing unit 1503 prints and outputs the tint block synthesis output document according to the information on the input tint block synthesis output document image data. As a result, the copy-forgery-inhibited pattern image can be synthesized and output to an area (for example, a white background area) having a specific pixel value of the input document image.

  According to the above-described embodiment, the background threshold pattern and the latent image threshold pattern which are already binarized patterns, the latent image background area designating image which is a binary image designating the latent image part and the background part, and the camouflage area are obtained. By performing a logical operation using a camouflage area image, which is a binary image to be specified, and bit information indicating whether the pixel value of the input image is a predetermined pixel, it is efficiently applied to the predetermined area of the input image. A tint block image can be arranged and synthesized.

  In addition, a background threshold pattern and a latent image threshold pattern that are binary images, a latent image background area designation image that is a binary image that designates a latent image portion and a background portion, and a camouflage area image that is a binary image that designates a camouflage area By generating a copy-forgery-inhibited pattern image based on a logical operation using, a copy-forgery-inhibited pattern image can be generated at high speed and with a reduced memory.

  Whether to copy the copy-forgery-inhibited pattern image into the input image by referring to the pixel value of the input image as necessary and performing a logical operation using bit information indicating whether the pixel value of the input image is a predetermined pixel or not. If it is determined whether or not, the tint block image can be efficiently arranged in a predetermined area (for example, a white area) of the input image.

  Up to this point, the method for generating the copy-forgery-inhibited pattern image and the method for synthesizing the copy-forgery-inhibited pattern image with the input original image have been described in detail. However, when the copy-forgery-inhibited pattern image is actually output using a printer, the latent image portion and the background portion are not necessarily displayed due to various causes. It is not always output at the intended density.

  Reasons include printer engine characteristics and dither matrix output of threshold patterns, individual printer differences, printing environment such as humidity and temperature, engine durability, differences in paper (media), printer ink and toner Concentration instability depending on various conditions such as differences can be mentioned. That is, the optimum input gradation for each of the background portion and latent image portion dither matrix may differ depending on the printer model, dither matrix, individual printer, printing environment, paper, ink, toner, and the like. .

  Therefore, even when the engine characteristics and the printing environment of the printer are different, it is necessary to generate a copy-forgery-inhibited pattern image after obtaining a background threshold pattern and a latent image threshold pattern having substantially the same density during printing. However, it is practically difficult to automatically calculate the optimum background threshold pattern and latent image threshold pattern in consideration of all the fluctuation factors including fluctuation due to the printing environment.

  Therefore, before executing the tint block synthesizing printing apparatus, a function for obtaining a background threshold pattern and a latent image threshold pattern in which the density of the background portion and the latent image portion are almost the same for each printer, that is, a tint block density calibration function is implemented. Necessary.

  As a method for implementing this tint block density calibration function, a method of adjusting the gradation of the input image signal to one or both of the background dither matrix and the latent image dither matrix and adjusting the density to be approximately equal is conceivable. .

  FIG. 16 is a diagram illustrating a background threshold pattern obtained by performing threshold processing with a dither matrix on the latent image threshold pattern and the gradations of a plurality of input image signals. In FIG. 16, reference numeral 1601 denotes a latent image threshold pattern obtained by inputting gradation 6 to a latent image dither matrix having 10 pixels on a side, and the area ratio of black pixels is 6%.

  On the other hand, 1602 to 1604 are background threshold patterns obtained by inputting gradations 12, 16, and 20 to a background dither matrix of 16 pixels on each side, and the area ratio of black pixels is 4.69%, 6. 25% and 7.81%. If the background dither matrix is 4 × 4 pixels and the density adjustment is performed by changing the gradation of the input image signal with respect to the background dither matrix of 4 × 4 pixels, the area ratio of black pixels is 4 × 4 + 1 = Since there is only a 17-step range and only a gradation change of about 6% step is given, delicate density adjustment cannot be performed.

  However, as shown in 1602 to 1604, the background threshold pattern output from the dither matrix having a large number of expressible gradations can be finely adjusted in density by selecting the gradation of the input image signal. It turns out that it is suitable.

  The outline of the background pattern density test printing for realizing the background pattern density calibration function will be described below. The copy-forgery-inhibited pattern density test printing can be implemented by an application on a computer or a printer driver.

  FIG. 22 is a block diagram illustrating an internal configuration of an apparatus that executes a tint block density test print. As shown in FIG. 22, the apparatus for executing the tint block density trial printing is configured by a setting information input unit 2201, a pattern generation unit 2202, a trial printing tint block image generation unit 2203, a print data processing unit 2204, and a printing unit 2205. .

  Note that the configuration of the apparatus is not limited to this, and it is only necessary to have a configuration capable of solving the problems in the present invention. Further, it is not necessary to use a device dedicated to the background pattern density test printing.

  First, the setting information input unit 2201 performs a process of reading the setting information from an initial setting file in which the setting information is stored, or a process of receiving setting information input through the user interface. Next, the pattern generation unit 2202 generates a pattern necessary for generating a tint block based on the setting information input from the setting information input unit 2201, and outputs the pattern to the subsequent trial print tint block image generation unit. In this embodiment, the patterns generated from the input setting information are the background threshold pattern and the latent image threshold pattern. In the background pattern density trial printing process, the pattern generation unit 2202 generates a plurality of background threshold patterns and latent image threshold patterns.

  Next, a trial printed tint block image generation unit 2203 generates a trial printed tint block image based on the pattern input from the pattern generation unit 2202. Details of the trial-printed tint block image generated by the trial-printed tint block image generation unit 2203 will be described in detail later.

  Next, the print data processing unit 2204 performs necessary image processing on the test print copy-forgery-inhibited pattern image generated by the test print copy-forgery-inhibited pattern image generation unit 2203. However, the print data processing unit takes into account the pixel values (cyan, magenta, yellow, black) of the copy-forgery-inhibited pattern image in the copy-forgery-inhibited pattern composite output original image in consideration of the color mixture of a plurality of inks and toners during printing. Perform image processing. The trial print copy-forgery-inhibited pattern image that has undergone the necessary image processing is converted into a data format that can be interpreted by the printer (for example, a data format described in a page description language or a data format that has been expanded into a print bitmap), and is printed later. Part 2204. The printing unit 2204 prints out a test printed tint block image according to the input data.

  Next, a description will be given of a test print sheet in which a plurality of copy-forgery-inhibited pattern images (patches) generated by the test-printed copy-forgery-inhibited pattern image generation unit 2203 in which the densities of both the background portion and the latent image portion are changed are two-dimensionally arranged. A test print sheet in which the density of the background portion and the latent image portion is two-dimensionally changed is printed with a background pattern of the background portion and the latent image portion in one sheet. There are a plurality of patches having almost the same density. Accordingly, the background pattern density can also be presented to the user as a selectable input value.

  So far, in the on-demand copy-forgery-inhibited pattern output method using a printer, it has been described that the latent image background area designation image, the camouflage area designation image, and the color information can be freely selected by the user. If it is possible to provide a means for selecting the density of the tint block, there is an advantage that the user has more choices. Therefore, in order to improve the usability for the user, a device that can quickly find the optimum density of the tint block image is required. When a test printing sheet that is two-dimensionally arranged in a single sheet by changing the density of both the background portion and the latent image portion is used, the latent image portion has a preferable density, and the latent image portion and the background portion It is possible to quickly find a tint block density parameter (that is, a latent image threshold pattern and a background threshold pattern) for generating a tint block image in which the densities are substantially equal and the latent image clearly appears at the time of copying. A test printing sheet arranged two-dimensionally by changing the density of both the background portion and the latent image portion has not only a large amount of information obtained from one sheet, but also has excellent listability and high convenience. In addition, since the number of test print sheets to be output when the user searches for the optimum tint block density can be reduced, an effect that leads to a reduction in paper cost can be obtained.

  FIG. 17 is a diagram illustrating an example of a test printing sheet in which patches having different densities in the background portion and the latent image portion are two-dimensionally arranged. Each patch always includes a latent image portion and a background portion, and may include a camouflage. Each patch in FIG. 17 shows a latent image portion at the center and a background portion at the periphery. In the example shown in FIG. 17, the latent image background area designating image for designating the latent image portion and the background portion is a rectangular rectangle, but is not necessarily limited to a square, and is a character such as “invalid”. Alternatively, for example, the latent image portion and the background portion may be arranged so as to be easily visually determined, for example, arranged next to each other as separate patches.

  In the test printing sheet shown in FIG. 17, the density of the latent image portion is changed in the horizontal direction of the paper, and the density of the background portion is changed in the vertical direction. In advance, considering the engine characteristics of the printer, the gradation of the dither matrix, etc., the patch existing at the center of the patch array arranged in the vertical direction is set so that the densities of the latent image portion and the background portion are substantially equal. Even when there are density fluctuations due to deterioration of the environment and engine performance, it is easy to find a patch in which the density of the latent image portion and the background portion are substantially equal.

  However, since there is actually a density fluctuation depending on the printer characteristics and printing environment, the density of the latent image portion and the background portion are almost equal in the patch at the center of the patch array arranged in the vertical direction in the test print sheet. is not.

  In the test print sheet, the density of the background portion is high in one direction in the vertical direction (upward direction of the paper in FIG. 17), and the density of the background portion is light in the other direction (downward direction of the paper in FIG. 17). It is set to be.

  In the example shown in FIG. 17, the density of the background portion of the background pattern is changed in the vertical direction. However, as described above, as a method of changing the density of the background portion, the input image for the background portion dither matrix is used. There is a method for changing the gradation of a signal.

  For example, when the size of the background dither matrix is 16 × 16 pixels, the threshold pattern black is changed by changing the gradation of the input image signal by 4 for the background dither matrix as in the background threshold patterns 1602 to 1604 in FIG. The area ratio of the pixels changes by about 1.5%.

  In this embodiment, hereinafter, the amount of change in the gradation of the input image signal with respect to the background dither matrix when changing the density of the background portion by trial printing is referred to as “contrast step”, and the density adjustment unit of the background portion is large. This is an index that represents

  On the other hand, in the example shown in FIG. 17, the density of the latent image portion is changed in the horizontal direction. However, as a method of changing the density of the latent image portion, one of the input image signals to the latent image dither matrix There is a method in which the gray scale is fixed and the vertical and horizontal sizes of the latent image dither matrix are reduced.

  For example, if the threshold pattern is generated with the size of the latent image dither matrix being 10 × 10 and the gradation of the input image signal being 9, the area ratio of black pixels is 9%, and the size of the latent image dither matrix is 12 ×. When the threshold pattern is generated with the gradation of the input image signal being 9 and the gradation of the input image signal being 9, the area ratio of black pixels is 6.25%, the size of the latent image dither matrix is 14 × 14, and the gradation of the input image signal is When the threshold pattern is generated as 9, the area ratio of black pixels is about 4.6%.

  Therefore, the density of the latent image portion can be changed by changing the size of the latent image dither matrix. Note that when the size of the latent image dither matrix is 10 × 10, 12 × 12, and 14 × 14, the gradations that can be expressed are theoretically 10 × 10 + 1 = 101 levels, 12 × 12 + 1 = 145 levels, and 14 × 14 + 1. = 197 level.

  As another method for changing the density of the latent image portion, there is a method of fixing the size of the latent image dither matrix and changing the gradation of the input image signal with respect to the latent image dither matrix. For example, if the size of the latent image dither matrix is fixed to 10 × 10 and the gradation of the input image signal is changed to 6, 9, and 12, the black pixel area ratio of the output threshold pattern is 6% and 9%, respectively. % And 12%. However, if the dots are so small that the dots in the latent image portion disappear after copying, the necessary condition for the latent image portion that dots remain after copying is not satisfied. Therefore, the gradation of the input image signal with respect to the latent image dither matrix needs to be a certain level or higher.

  As another method, both the size of the latent image dither matrix and the gradation of the input image signal with respect to the latent image dither matrix may be changed to generate a latent image threshold pattern and change the density.

  FIG. 23 is a diagram illustrating a tint block composition printing apparatus having a tint block density calibration function. A selection information input unit 2301 and a pattern generation unit 2302 are arranged in the previous stage of the tint block composition printing apparatus (2303 in FIG. 23) shown in FIG. First, an internal configuration of a background pattern composition printing apparatus having a background pattern density calibration function will be described.

  First, the selection information input unit 2301 inputs information about a patch determined to be optimal (for example, a number printed in the vicinity of the patch) as selection information through a user interface. At this time, the optimum copy-forgery-inhibited pattern image patch has the darkness desired by the user, and the background portion and the latent image portion have substantially the same density, and the test printing sheet is copied by the target copying machine. In this patch, the latent image portion remains and the background portion disappears. If there is no target copying machine, copying may be performed with an available copying machine to investigate whether the latent image portion remains and the background portion disappears.

  Next, the pattern generation unit 2302 generates a pattern necessary for generating a background pattern based on the selection information input from the selection information input unit 2301, and inputs the pattern to the subsequent background pattern synthesis printing apparatus 2303. In this embodiment, the patterns generated from the input selection information are the background threshold pattern and the latent image threshold pattern.

  Next, the copy-forgery-inhibited pattern synthesis printing apparatus 2303 generates a copy-forgery-inhibited pattern image based on the background threshold pattern and the latent image threshold pattern input from the pattern generation unit 2302 in the previous stage, combines the copy-forgery-inhibited pattern image with the input document image, and outputs an output document. Print out. Since the processing in the tint block composition printing apparatus 2303 has already been described in detail, the description thereof is omitted.

  According to this embodiment, it is possible to provide a tint block composition printing apparatus having a tint block density calibration function.

  Although the density of the background portion and the latent image portion is equal during printing, the latent image portion may remain when the test printing sheet is copied by a target copying machine, but the background portion may not be completely lost.

  However, at this time, a patch whose density is greatly different from the density after copying of the latent image portion may be determined as an optimum patch. This is because if the latent image appears after copying, the effect as a forgery-suppressing tint block can be exhibited. In this embodiment, not only a patch in which the latent image portion remains and the background portion disappears after copying, but also a patch whose background portion after copying is sufficiently lower than the latent image portion is selected as the optimum patch. good.

  FIG. 18 is a flowchart showing the simplest test printing procedure. First, in accordance with an input from the user interface or the like, trial printing is started in step S1801. In step S1802, a process for reading the setting information from the initial setting file in which the setting information is stored or a process for receiving the setting information input through the user interface is performed. Next, in step S1803, a tint block density parameter for determining the print density of the latent image portion and the background portion when generating the tint block image is generated based on the setting information input in step S1802. In this embodiment, the background pattern density pattern generated from the input setting information is a background threshold pattern and a latent image threshold pattern. In step S1804, a test print sheet as shown in FIG. 17 is generated based on the tint block density parameter input in step S1803, and is printed out by the printer.

  In step S1805, the density of the latent image portion and the background portion in each patch of the test printing sheet is visually compared. In the visual evaluation, the density of the latent image portion and the background portion of the test print sheet is almost equal, and when the test print sheet is copied by the target copying machine, the latent image portion remains and the background portion is The optimal patch that disappears (or has sufficient contrast compared to the latent image portion) is selected by the number associated with the patch. For example, in the example shown in FIG. 17, patches with different densities are arranged in rows A, B, and C in the horizontal direction of the paper, and the density of the background portion is changed in the vertical direction of the paper. The patches are arranged, and a value indicating the darkness of the background portion is described beside each patch. Here, it is assumed that there is a patch having a preferable density as the copy-forgery-inhibited pattern image, and the optimal density of the patch having the optimal density is column A, and the value representing the density of the background portion is 16. In that case, the patch may be selected as A-16.

  As shown in FIG. 17, when the trial printing function that finds the optimum patch by one trial printing is realized, the darkness of the background portion and the latent image portion is almost equal in the trial printing sheet, and the latent image is visually observed. Inconspicuous patches need to be present in the proof sheet. In such a case, it is necessary to grasp the threshold pattern range in which the density of the background portion and the latent image portion are substantially equal as the initial device density parameter (device profile data) in consideration of the characteristics of the printer.

  As a specific example of the initial device density parameter, each latent image threshold pattern and background part for generating a tint block image in which the latent image portion has the densities of the A, B, and C columns of the test printing sheet are the A row and B Each background threshold pattern (contrast zero parameter in each column) having a printing density substantially equal to the density of columns C and C, and density change width of the background portion changed in the vertical direction of the test printing sheet (contrast step parameter in each column) Etc. The density change range of the background portion (the range in which the background threshold pattern in each column is changed. In FIG. 17, the A column is 12 to 20) can be used as the initial parameter.

  In step S1806, the number (for example, A-16) relating to the patch selected in step S1805 is input as selection information through the user interface or the like. In step S1807, a tint block density parameter for determining the print density of the latent image portion and the background portion of the tint block image is generated based on the information input in step S1806. Specifically, the tint block density parameter corresponds to a latent image threshold pattern and a background threshold pattern in which the density of the background portion and the latent image portion are substantially equal and the background portion disappears during copying. In step S1808, a copy-forgery-inhibited pattern image is generated based on the copy-forgery-inhibited pattern density parameter generated in step S1807, combined with the input document image, and printed out. The processing in this step is the same as that in the tint block synthesis printing apparatus described in FIG.

  In the trial printing procedure shown in FIG. 18, density calibration cannot be realized unless an optimum patch in which the density of the background portion and the latent image portion are almost equal can be found in the trial printing sheet by one trial printing. However, if the density variation of the printer is large or if the gradation reproduction characteristics of the printer have a large dependency on the model or individual, if the large value is used as the contrast step, the density of the background portion and the latent image portion is almost equal. There may be a case where an optimal position that is the same cannot be found once.

  FIG. 19 is a flowchart of the trial printing in which the density adjustment function is further enhanced than the flowchart of the trial printing shown in FIG. The major difference from FIG. 18 is that it has two types of rough test printing and fine test printing.

  Step S1930 shown in FIG. 19 is a step for executing rough test printing, and step S1940 is a step for executing fine test printing. Hereinafter, the rough test print that is the primary test print is called “course tuning”, and the fine test print that is the secondary test print is called “fine tuning”.

  In steps S1930 and S1940, substantially the same processing as steps S1804 to S1806 in the simple test printing shown in FIG. 18 is executed.

  FIG. 20 is a diagram showing two types of sheets used in the trial printing whose processing procedure is shown in FIG. In FIG. 20, 2001 is an example of a coarse tuning trial print sheet output in step S1904, and 2002 is an example of a fine tuning trial print sheet output in step S1908.

  Hereinafter, the two-stage test printing process will be described in order with reference to FIGS. 19 and 20. First, in the primary test printing (course tuning) shown in FIG. 19, first, test printing is started in step S1901 according to the input from the user interface or the like. In step S1902, a process for reading the setting information from the initial setting file in which the setting information is stored is performed, or a process for receiving setting information input through the user interface is performed.

  Next, in step S1903, a tint block parameter for determining the print density of the latent image portion and the background portion of the tint block image is generated based on the setting information input from step S1902. In this embodiment, the background pattern density parameters generated from the input setting information are the background threshold pattern and the latent image threshold pattern. In step S1904, a trial printing sheet for course tuning as shown in 2001 is generated and printed out by the printer.

  In the course tuning test print sheet 2001, as in FIG. 19, the density of the latent image portion changes in patches arranged in the horizontal direction of the paper, and the density of the background portion changes in patches arranged in the vertical direction. In the course tuning test print sheet 2001, the background threshold patterns in the patches arranged in the vertical direction are each generated by changing the gradation of the input image signal for dither by 8 steps (that is, the contrast step is set). 8).

  Note that when the input gradation for the background dither matrix is 0, no dots are formed in the background portion, so that the background pattern image is not suitable. Therefore, another non-zero value (for example, 8) may be set for the gradation close to 0. However, when the case where the input gradation with respect to the background dither matrix is 0 is output, the appearance of the latent image (latent image portion) in the ideal state where the background portion has completely disappeared, that is, the latent image has been lifted by copying. There is also an advantage that the contrast of the white background can be confirmed.

  In the course tuning test print sheet 2001, since the density change of the background portion is large between patches in the vertical direction, it is difficult to precisely adjust the density of the background portion and the latent image portion. However, it is possible to quickly narrow down the range of the tint block density parameter for generating the tint block image in which the density of the background portion and the latent image portion is substantially the same.

  When creating a threshold pattern using Bayer-type dither, if the input gradation exceeds half of the gradation 128, the generated threshold pattern has the effect that the dots touch each other and are not isolated dots, and the background portion disappears during copying. It is difficult to obtain. Therefore, for the purpose of searching for an optimum copy-forgery-inhibited pattern image, it is sufficient that the gradation of the background portion covers 0 to 128.

  In the course tuning test print sheet 2001 of FIG. 20, the gradation of the background portion is shown only in the range from 0 to 32 in order to make the drawing easier to see, but is represented by a 16 × 16 background threshold pattern. It is desirable to cover all gradations (0 to 256) or gradations (0 to 128) that can be used as a background portion.

  Here, in the trial printing sheet for course tuning 2001, the gradation of the background portion that is expected to obtain substantially the same darkness as the latent image portion (for example, 0 to 32 in the case of the trial printing sheet for course tuning 2001). The explanation will be continued assuming that it is substantially covered.

  When finding the optimum copy-forgery-inhibited pattern density parameter in order to generate a copy-forgery-inhibited pattern image with similar print densities in the latent image area and the background area on a printer with unknown gradation reproduction characteristics or a printer with a large background fluctuation due to the environment. First, a background threshold pattern may be generated with a rough contrast step so as to cover the entire range of values that can be taken by the section, or a range of values that can be taken substantially, and a test print sheet may be output. By doing so, the density of the background part and the latent image part is almost the same without any prior knowledge, even for printers where the gradation reproduction characteristics of the background part and the latent image part are unknown, or printers with large density fluctuations due to the printing environment and durability. It is possible to narrow down the range of the background pattern density parameter. Such a course tuning test print sheet is designed to be applied to a large number of printers in general, and is highly valuable in that it does not require individual setting by a device.

  Next, in step S1905, the density of the latent image portion and the background portion in each patch of the test printing sheet is visually compared. In this case, processing similar to that described in step S1805 is performed. At this time, since the contrast step of the background portion is large, there is a high possibility that the optimum patch number cannot be found. Therefore, in such a case, a range where an optimal patch is predicted to exist is selected.

  In this course tuning, there are several methods for designating a range where an optimum patch is expected to exist. One method is a method of designating a range where an optimal patch is predicted to exist as a center value. For example, when the third patch from the top (A-16) in the A row of the course tuning test print sheet 2001 has the smallest difference in density between the latent image portion and the background portion, the third patch from the top in the A row. (A-16) is designated as the center where the optimum patch is predicted to exist.

  In the fine tuning described later, if the background density is changed more finely around the specified patch, there is an optimum tint block density parameter for generating a tint block image in which the latent image portion and the background portion have substantially the same density. Probability is high.

  Another method is a method of designating an interval in which an optimal patch is predicted to exist. For example, in row A of the course tuning test print sheet 2001, the third patch (A-16) from the top has a lighter background than the latent image portion, and the fourth patch (A-24) from the top is the latent image. The background part is darker than the part. In this case, there is a high possibility that an optimum patch exists between the third patch (A-16) and the fourth patch (A-24) from the top of the A column. Therefore, a section where the magnitude relationship between the density of the background portion and the latent image portion changes is designated as a section where the optimum patch is predicted to exist.

  In this case, it is preferable to input the numbers of both the third patch (A-16) and the fourth patch (A-24) from the top of the A column. However, there is a possibility that the method of inputting two input values to the operation menu and designating the section may be complicated, so that the user has the third patch (A-16) and the fourth patch ( The intermediate value of A-24) may be calculated, and the intermediate value of (A-20) may be input as the center where the optimal patch is predicted to exist.

  Similar to the A-line patch, the two-dimensional information shown in the fine tuning trial print sheet 2002 is input to the B-line and C-line patches by inputting information about the neighborhood or section where the optimum patch is predicted to exist. It is also possible to output using a trial printing sheet.

  This fine tuning test print sheet 2002 designates patches (B-8) and (C-8) with the smallest density difference between the latent image portion and the background portion not only in the A row but also in the B and C rows. ing. In this case, it is possible to realize an effect that the tint block parameters having different densities can be determined by one trial printing.

  However, when searching for an optimal patch by changing the density of the background part only for the patches existing in the A column, a trial in which the density of the background part and the latent image part is two-dimensionally changed in fine tuning. There is no need to print a printed sheet, and a test printed sheet in which only the density of the background portion is changed with respect to the latent image portion having the designated density may be output.

  Next, in step S1906, based on the visual evaluation in step S1905, the user who performs the trial printing inputs information on the center or section where the optimum patch is predicted to exist from the trial printing sheet through the user interface. Here, although not shown in FIG. 19, as the initial setting information when executing the fine tuning 1940, the information previously input in step S1906 is saved in the setting file, and the file is read out. It may be used.

  Next, in step S1907, a background pattern density parameter necessary for generating a background pattern image in which the densities of the background portion and the latent image portion are substantially equal is generated based on the information input in step S1906. In the case of the present embodiment, a plurality of background threshold patterns to be printed as densities between the ranges input in step S1906 and a latent image threshold pattern having a selected density are generated.

  In step S1908, a fine tuning test print sheet is generated and printed based on the tint block density parameter generated in step S1907. For example, in the fine tuning trial printing sheet 2002 shown in FIG. 20, the third patch (A-16) from the top of the A row of the coarse tuning trial printing sheet 2001 selected by the course tuning in step S1907, and the top of the B row. The contrast step is set to 2 around the second patch (B-8) from the top and the second patch (C-8) from the top of the C column, and the gradation of the input image signal with respect to the background dither matrix is further reduced. It is changing. Therefore, it is possible to detect a patch in which the density of the background portion and the density of the latent image portion are closer than those of the course tuning test print sheet 2001.

  As described above, in step S1940 in which fine tuning is executed, a fine-tuning test print that can more accurately find a patch having a density close to the background portion and the latent image portion than in step S1930 in which coarse tuning is executed. Generate a sheet. In step S1909, the density of the latent image portion and the background portion in each patch of the test printing sheet is visually compared. As a result of visual evaluation, the density of the latent image portion and the background portion is almost equal, and when the test printing sheet is copied with the target copying machine, the latent image portion remains and the background portion disappears (or the latent image). A patch having a sufficient contrast with respect to the copy) is searched, and an optimum patch number (for example, (A-18)) is selected from the test printing sheet. At this time, if two-dimensional test printing is performed with the density of the latent image portion changed, a patch having a preferable density as a copy-forgery-inhibited pattern image can be selected not only from the A row but also from the B and C rows.

  In step S1910, the number related to the patch selected in step S1909 is input as selection information through the user interface. In step S1911, a background pattern density parameter necessary for generating a background pattern image in which the print densities of the background portion and the latent image portion are approximated is generated based on the information input in step S1910. Specifically, in the case of the present embodiment, this corresponds to generation of a latent image threshold pattern and a background threshold pattern in which the density of the background portion and the latent image portion are substantially equal. In step S1912, a copy-forgery-inhibited pattern image is generated based on the copy-forgery-inhibited pattern density parameter generated in step S1911, and is combined with the input document image and printed out. The processing in this step is the same as the processing in the forgery-inhibited tint block printing output device described in FIG.

  Note that it is not always necessary to perform both the processing in step S1930 for executing the course tuning and the processing in step S1940 for executing the fine tuning. For example, the course tuning step S1930 is performed only when the printer is installed, at regular intervals of maintenance, or when the copy-forgery-inhibited pattern image is not properly output. The processing may be omitted and only the processing of step S1940 of fine tuning may be performed.

  By omitting the course tuning during normal use, the time required for the background pattern density calibration can be reduced. At this time, information regarding parameters suitable as the tint block obtained in step S1930 for executing the course tuning is stored in a setting file. When only fine tuning is executed without course tuning, a fine tuning trial print sheet may be generated by reading a range in which patches are output on the fine tuning trial print sheet 2002 from the saved setting file. In this case, it is desirable from the viewpoint of usability to design so as to reduce the number of times of returning to the course tuning even when the printing environment changes.

  For example, the course tuning test print sheet 2001 is printed, and in row A, (A-16) has the smallest difference in density between the latent image portion and the background portion, and fine tuning is performed with fine tuning centered on (A-16). Suppose you want to make settings. However, in an actual printer, it is assumed that density fluctuations due to the environment occur around (A-20).

  In the fine tuning test print sheet 2002, if the density fluctuation due to the environment is centered on (A-16), the range of the previous and subsequent contrast steps 4 (ie, from A-12 to A-20) can be followed. Yes, there are few opportunities to return to course tuning. However, when the density fluctuation due to the environment is centered on (A-20), the fine tuning trial print sheet 2001 has only a range of contrast step 8 in one direction (ie, from A-12 to A-20). If it cannot be followed and the density changes in the direction of A-24, the course tuning must be returned.

  In such a case, for example, when the center for fine density change by fine tuning is selected from the patch of the coarse tuning trial printing sheet 2001, the contrast steps before and after the coarse tuning trial printing sheet 2001 are set to the fine tuning trial printing sheet 2002. When the contrast step required before and after is set to twice, the range from the center patch selected on the course tuning test print sheet 2001 to the adjacent patch can be covered by fine tuning, so the process returns to course tuning. Opportunities can be reduced.

  In another example, in fine tuning, not only before and after the patch selected as the center in course tuning, but also a larger number of patches to be output may be set to cover the range up to several patches before and after. . Even in this case, the chance of returning to the course tuning can be reduced even if some concentration fluctuation exists.

  At this time, although not shown, the apparatus or software that realizes the two-stage trial printing function whose processing procedure is shown in FIG. 19 is the information obtained by starting the trial printing from the course tuning or by the course tuning executed last time. If the start from the course tuning is selected, the process shown in steps S1902 to 1912 is sequentially executed to start the process from the fine tuning. Is selected, the stored information related to the course tuning is read (corresponding to the processing in step S1902), the tint block parameter is generated (corresponding to the processing in step S1903), and the processing after fine tuning (steps S1908 to 1912). Run .

  The function of step S1930 for executing the course tuning may be a detailed function (maintenance function) that can be executed only by a service person who performs printer installation or maintenance, and may not be operated by a general user. For example, in order to execute this step S1930, software that requires a password can be implemented.

  In addition, when the portions other than the printing unit (printer controller and printer engine) of the tint block composition printing apparatus of FIGS. 1 and 15 are implemented as software in a computer, the OS access restriction function is used to enable a non-computer administrator. May restrict access so that the function of step S1930 cannot be executed.

  With the settings as described above, it is possible to prevent a trouble that an optimum copy-forgery-inhibited pattern image cannot be found only by step S1940 for executing fine tuning, which is caused by a simple setting mistake or intentional change by a third party.

  Further, for the course tuning step S1930 and the fine tuning step S1940, access restrictions may be set by requesting a password or a computer administrator authority. This not only prevents general users from getting into the trouble of finding the optimal copy-forgery-inhibited pattern image due to a simple setting mistake or intentional change by a third party, but also without being aware of the density calibration of the copy-forgery-inhibited pattern. There is an advantage that a manuscript with a tint pattern can be easily printed out.

  Further, the fine tuning test print sheet 2002 of FIG. 20 shows a sample in which the density of both the background portion and the latent image portion is changed, but the desired density of the latent image portion is determined by coarse tuning, and fine tuning is performed. The test print sheet may be a test print sheet that outputs only patches in which the density of the background portion is changed with respect to the determined density of the latent image portion.

  In that case, since the area of patches that can be output within one sheet increases, it is possible to output a large number of patches in one image by reducing the contrast step, or to combine and print on an actual input document. A patch may be output using a latent image background area designating image and a camouflage area designating image to be performed.

  Further, in the coarse tuning trial printing sheet 2001 and the fine tuning trial printing sheet 2002 shown in FIG. 20, the density of the background portion and the density change width may be the same for each column or may be different for each column. In addition, the layout configuration of the tint block image may be different between the trial tuning sheet 2001 for course tuning and the trial printing sheet 2002 for fine tuning.

  Finally, a multi-step test printing process procedure that generalizes the two-step test printing functions of course tuning and fine tuning will be described.

  FIG. 21 is a flowchart showing a processing procedure for multi-stage test printing having a more advanced function. First, in accordance with an input from the user interface or the like, trial printing is started in step S2101. In step S2102, initial setting information for generating a tint block image is read. For example, it is assumed that the initial setting information is stored in a setting file in an HDD or a memory on a computer and can be read by software on the computer.

  In step S2103, a tint block density parameter for determining the density of the latent image portion and the background portion of the tint block image is generated based on the setting information input in step S2102. Specifically, in the case of the present embodiment, this corresponds to generation of a latent image threshold pattern and a background threshold pattern in which the density of the background portion and the latent image portion are substantially equal.

  In step S2104, a test print sheet is generated and printed based on the tint block density parameter generated in step S2103. As shown in FIG. 17, the test printing sheet may be arranged by changing the density of the background part and the latent image part two-dimensionally, or only the density of the background part may be changed. . Next, in step S2105, the density of the background portion and the latent image portion is substantially equal to each patch of the test print sheet, or each patch of the test print sheet copied by the target copier is a latent image. It is visually evaluated whether the area remains and the background area disappears (or there is sufficient contrast compared to the latent image area).

  Next, in step S2106, if the density of the background portion and the latent image portion is approximately equal in the test printing sheet, and the image is copied by the target copying machine, the latent image portion remains and the background portion disappears (or If there is a patch having sufficient contrast as compared with the latent image portion, the process proceeds to step S2108. However, the density of the background portion and the latent image portion is substantially equal, and the latent image portion remains and the background portion disappears when copying with the target copying machine (or there is sufficient contrast compared to the latent image portion). If no patch exists, the process proceeds to step S2107.

  In step S2107, as already described with reference to FIG. 10, information on the center or section where the optimum patch is predicted to exist from the test printed sheet is input through the user interface using the number associated with the patch. At this time, a contrast step which is an index for determining the width of density change in the background portion is also input.

  The contrast step is desirably set to a smaller value than the contrast step used in the test print sheet that has already been output. The contrast step value may be set automatically by the software.

  In step S2108, a tint block density parameter for determining the print density of the latent image portion and the background portion of the tint block image is generated based on the information input in step S2107. Next, the process returns to step S2104, a test print sheet is printed based on the tint block density parameter generated in step S2108, and the process proceeds to step S2105 again to perform visual evaluation. Until the optimal patch is found, the information regarding the center or section where the optimal patch is predicted to exist is reset and the loop is repeated.

  In step S2109, the density of the background portion and the latent image portion selected in step S2105 is approximately equal through the user interface or the like, and the background portion disappears and the latent image portion remains when copied by the target copier. Enter the number associated with the patch. In step S2110, a tint block density parameter for determining the density of the latent image portion and the background portion of the tint block image is generated based on the information input in step S2109. Specifically, in the case of this embodiment, this corresponds to the generation of a latent image threshold pattern and a background threshold pattern in which the density of the background portion and the latent image portion are substantially equal, and the background portion disappears during copying.

  In step S2111, a copy-forgery-inhibited pattern image is generated based on the copy-forgery-inhibited pattern density parameter generated in step S2110, and is combined with the input document image and printed out. The processing in this step is the same as that in the tint block synthesis printing apparatus described in FIG.

  Finally, a modified example of the test printing sheet shown in FIGS. 17 and 20 will be described.

  FIG. 24 is a diagram illustrating a modified example of the test printing sheet. In the test printing sheets shown in FIGS. 17 and 20, the background portion and the latent image portion are arranged in one patch. In the test printing sheet shown in FIG. 24, each of the rows A, B, and C is composed of a latent image portion rectangle (2401, 2403, 2405) and a background portion rectangle (2402, 2404, 2406). The density is fixed inside and the density is different for each column A, B, C.

  In addition, the density changes smoothly inside the background rectangle (a gradation from light to dark), and the gradation that forms the background rectangle is based on the background threshold based on the background dither matrix. Generated with a pattern. Next to the rectangle of the background part, a number for identifying the background threshold pattern is assigned, and when the density of the latent image part and the density of the background part are visually designated, the position where the density is almost equal, As with the test printing sheets of FIGS. 17 and 20, for example, it can be specified by a number such as (A-16).

  If the trial printing sheet shown in FIG. 24 is used, it is possible to realize a rough trial printing function or a fine trial printing function as in the trial printing sheets of FIGS. In rough trial printing, the gradation range of the background area where the density of the latent image area and background area feel almost equal is specified by the number assigned to the background area. In the fine trial printing, the specified gradation range is more It is possible to enlarge and precisely compare the density of the background portion and the latent image portion.

  Further, the test printing sheet shown in FIG. 24 may be used in place of the course tuning test printing sheet 2001 shown in FIG. Since the density of the background portion continuously changes, it is easier to determine a point where the density of the latent image portion and the background portion becomes substantially the same as compared to the coarse tuning trial printing sheet 2001 that roughly changes the gradation of the background portion. There are benefits. It is also possible to apply camouflage patterns to the A column, the B column, and the C column, respectively, and compare the densities of the background portion and the latent image portion using a ground pattern image that is closer to the ground pattern image that is finally generated.

  Next, Embodiment 2 according to the present invention will be described in detail with reference to the drawings. In the second embodiment, each process described in the first embodiment is executed by a computer.

  FIG. 25 is a block diagram illustrating a basic configuration of a computer according to the second embodiment. For example, in this computer, when all functions except the printing unit (or the printer engine of the printing unit) in FIGS. 1, 15, 22, and 23 in the first embodiment are executed, each functional configuration is expressed by a program. By loading the information into the computer, all functions except for the printing unit (or the printer engine of the printing unit) in FIGS. 1, 15, 22, and 23 in the first embodiment can be realized.

  In FIG. 25, reference numeral 2511 denotes a CPU, which controls the entire computer using programs and data stored in a RAM 2512 and ROM 2513, and performs each process described in the first embodiment. Reference numeral 2512 denotes a RAM which has an area for temporarily storing programs and data loaded from the external storage device 2518 and programs and data downloaded from other computer systems 2524 via an I / F (interface) 2523. An area required for the CPU 2511 to perform various processes is provided.

  Reference numeral 2513 denotes a ROM which stores computer function programs and setting data. Reference numeral 2514 denotes a display control apparatus, which performs control processing for displaying images, characters, and the like on the display 2515. Reference numeral 2515 denotes a display for displaying images, characters, and the like. As a display, a CRT, a liquid crystal screen or the like can be applied.

  Reference numeral 2516 denotes an operation input device, which is configured by a device that can input various instructions to the CPU 2511 such as a keyboard and a mouse. In addition, when manually inputting a camouflage area designation image, a latent image background area designation image, or the like, these can be inputted via the operation input device 2516. Reference numeral 2517 denotes an I / O for notifying the CPU 2511 of various instructions input via the operation input device 2516.

  Reference numeral 2518 denotes an external storage device that functions as a large-capacity information storage device such as a hard disk, and generates an OS (Operating System) and a program for causing the CPU 2511 to execute the processing of the first embodiment, a background dither matrix, and a latent image dither matrix. The copy-forgery-inhibited pattern image, the input original image, and the like are stored. Information is written to the external storage device 2518 and information is read from the external storage device 2518 via the I / O 2519.

  A printer 2521 outputs a document or an image, and output data is sent from the RAM 2512 or the external storage device 2518 via the I / O 1422. Examples of printers for outputting documents and images include ink jet printers, laser beam printers, thermal transfer printers, and dot impact printers.

  Reference numeral 2530 denotes a bus for connecting the CPU 2511, the ROM 2513, the RAM 2512, the I / O 2522, the I / O 2519, the display control device 2514, the I / F 2523, and the I / O 2517.

  In the second embodiment, the processing except the printing unit of the tint block synthesis printing apparatus and the tint block synthesis printing apparatus having a trial printing function is executed by the computer. However, the processing is performed by the computer using a dedicated hardware circuit in the printer. You may act as a proxy.

  In addition, all of the embodiments described above are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be construed as being limited thereto. . That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

  Even if the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), it can be applied to a device (for example, a copier, a facsimile machine, etc.) composed of a single device. It may be applied.

  Another object of the present invention is to supply a recording medium recording software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and store the computer (CPU or MPU) of the system or apparatus in the recording medium. Needless to say, this can also be achieved by reading and executing the programmed program code.

  In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiment, and the recording medium storing the program code constitutes the present invention.

  As a recording medium for supplying the program code, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like is used. be able to.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Further, after the program code read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

FIG. 3 is a block diagram illustrating internal processing of the tint block composition printing apparatus according to the first embodiment. 6 is a flowchart illustrating an internal processing procedure of the tint block image generation unit 101 according to the first exemplary embodiment. It is a figure which shows an example of a 4x4 spiral dither matrix. FIG. 4 is a diagram illustrating a threshold pattern (dot arrangement) obtained by performing threshold processing on a predetermined input image signal using the 4 × 4 spiral dither matrix of FIG. 3. It is a figure which shows an example of a 4x4 Bayer type dither matrix. FIG. 6 is a diagram illustrating a threshold pattern (dot arrangement) obtained by performing threshold processing on a predetermined input image signal using the 4 × 4 Bayer-type dither matrix of FIG. 5. It is a figure for comparing the area ratio of the black pixel of a background threshold value pattern and a latent image threshold value pattern. It is a figure showing the relationship between the area ratio of the black pixel of the threshold pattern obtained by threshold-processing an input image signal with a dither matrix, and the density when a threshold pattern is printed. FIG. 2 is a schematic diagram illustrating a state in which a tint block image is generated using the tint block synthesis printing apparatus of FIG. 1. It is a figure which shows an example of the latent image background area | region designation | designated image 115 and the camouflage area | region designation | designated image 117. FIG. 5 is a diagram illustrating an example of a latent image threshold pattern 114 and a background threshold pattern 116. FIG. It is a figure which shows a part of tint block image produced | generated by the tint block generation part 101 by the boundary process. FIG. 10 is a schematic diagram illustrating a composition process of an input document image and a tint block image. It is a schematic diagram showing a method of synthesizing a tint block image with an input document image having no layer structure in which various images are already synthesized. It is a block diagram showing an internal configuration of a tint block synthesis printing apparatus for synthesizing a tint block image with an input document image having no layer structure in which various images have already been synthesized. It is a figure which shows the background threshold value pattern obtained by threshold-processing with a dither matrix with respect to the latent image threshold value pattern and the gradation of several input image signal. It is a figure which shows an example of the test printing sheet which arrange | positioned the patch which changed the density | concentration of a background part and a latent image part two-dimensionally. It is a flowchart showing the simplest test printing procedure. FIG. 19 is a flowchart of trial printing in which the density adjustment function is further strengthened than the flowchart of trial printing shown in FIG. 18. FIG. 19 is a diagram showing two types of sheets used in the trial printing whose processing procedure is shown in FIG. It is a flowchart which shows the process sequence of the multistep test printing which has a more advanced function. FIG. 2 is a block diagram illustrating an internal configuration of an apparatus that executes a tint block density test print. It is a figure which shows the tint block composition printing apparatus provided with the tint block density calibration function. 6 is a diagram illustrating a modified example of the test printing sheet described in Embodiment 1. FIG. FIG. 10 is a block diagram illustrating a basic configuration of a computer according to a second embodiment.

Explanation of symbols

101 Copy-forgery-inhibited pattern image generation unit 102 Composition unit 103 Print data processing unit 104 Printing unit

Claims (14)

An image processing apparatus for generating a tint block image patch including a latent image portion and a background portion,
First tint block image patch group output means for outputting a first tint block image patch group generated by changing at least one of the density parameter of the latent image portion and the density parameter of the background portion;
An input unit that inputs information indicating at least one copy-forgery-inhibited pattern image patch of the first copy-forgery-inhibited pattern image patch group output by the first copy-forgery-inhibited pattern image patch output unit based on an instruction from the user;
Second copy-forgery-inhibited pattern image patch group generation means for generating a second copy-forgery-inhibited pattern image patch group based on the density parameter used to generate the copy-forgery-inhibited pattern image patch indicated by the information input by the input unit;
Second tint block image patch group output means for outputting the second tint block image patch group generated by the second tint block image patch group generating means;
A second input unit for inputting information indicating one copy-forgery-inhibited pattern image patch in the second copy-forgery-inhibited pattern image patch group output by the second copy-forgery-inhibited pattern image patch output unit based on an instruction from the user;
On the basis of the density parameters used to generate the copy-forgery-inhibited pattern image patches indicated by the information input by the second input means, images processor you; and a background pattern image generating means for generating a background pattern image . The second copy-forgery-inhibited pattern image patch group generation means includes:
Based on the density parameter used to generate the tint block image patch indicated by the information input by the input unit, a density parameter that changes with a smaller degree of change than the density parameter of the first tint block image patch group is generated, The image processing apparatus according to claim 1, wherein the second tint block image patch group is generated based on the generated density parameter. The second copy-forgery-inhibited pattern image patch group generation means includes:
Based on the density parameter that includes the density parameter used to generate the copy-forgery-inhibited pattern image patch specified by the information input by the input unit and changes with a degree of change smaller than the density parameter of the first copy-forgery-inhibited pattern image patch group. Te, the image processing apparatus according to claim 1, characterized in that generating the second copy-forgery-inhibited pattern image patch group. The second copy-forgery-inhibited pattern image patch group generation means includes:
Based on the density parameter that changes with a degree of change smaller than the density parameter of the first copy-forgery-inhibited pattern image patch, centered on the density parameter used to generate the copy-forgery-inhibited pattern image patch indicated by the information input by the input means, The image processing apparatus according to claim 1, wherein the second tint block image patch group is generated. The first copy-forgery-inhibited pattern image patch group output means includes:
The image processing apparatus according to any one of claims 1 to 4, characterized in that further outputs information indicating each of the tint block image patch of the first background pattern image patch group. The second copy-forgery-inhibited pattern image patch group output means includes:
The image processing apparatus according to any one of claims 1 to 4, characterized in that further outputs information indicating each of the tint block image patch of the second copy-forgery-inhibited pattern image patch group. An image processing method for generating a tint block image patch including a latent image portion and a background portion,
A first tint block image patch group output step of outputting a first tint block image patch group generated by changing at least one of the density parameter of the latent image portion and the density parameter of the background portion;
An input step of inputting information indicating at least one copy-forgery-inhibited pattern image patch in the first copy-forgery-inhibited pattern image patch group output in the first copy-forgery-inhibited pattern image patch output step based on an instruction from the user;
A second copy-forgery-inhibited pattern image patch group generation step for generating a second copy-forgery-inhibited pattern image patch group based on the density parameter used to generate the copy-forgery-inhibited pattern image patch indicated by the information input in the input step;
A second tint block image patch group output step for outputting the second tint block image patch group generated in the second tint block image patch group generating step;
A second input step of inputting information indicating one copy-forgery-inhibited pattern image patch of the second copy-forgery-inhibited pattern image patch group output in the second copy-forgery-inhibited pattern image patch group output step based on an instruction from the user;
On the basis of the density parameters used to generate the copy-forgery-inhibited pattern image patches indicated by the information input by the second input step, images processing how to; and a background pattern image generation step of generating a background pattern image . The second tint block image patch group generation step includes:
Based on the density parameter used to generate the tint block image patch indicated by the information input in the input step, a density parameter that changes with a smaller degree of change than the density parameter of the first tint block image patch group is generated, 8. The image processing method according to claim 7 , wherein the second copy-forgery-inhibited pattern image patch group is generated based on the generated density parameter. The second tint block image patch group generation step includes:
Based on the density parameter that includes the density parameter used to generate the copy-forgery-inhibited pattern image patch specified by the information input in the input step and changes with a degree of change smaller than the density parameter of the first copy-forgery-inhibited pattern image patch group. The image processing method according to claim 7 , wherein the second tint block image patch group is generated. The second tint block image patch group generation step includes:
Based on the density parameter that changes with a degree of change smaller than the density parameter of the first background pattern image patch group around the density parameter used for generating the background pattern image patch indicated by the information input in the input step, The image processing method according to claim 7 , wherein the second tint block image patch group is generated. The first tint block image patch group output step includes:
11. The image processing method according to claim 7 , further comprising: outputting information indicating each of the various background pattern image patches of the first background pattern image patch group. The second tint block image patch group output step includes:
11. The image processing method according to claim 7 , further comprising: outputting information indicating each of the local pattern image patches of the second background pattern image patch group. A program for causing a computer to execute each procedure of the image processing method according to any one of claims 7 to 12 . A computer-readable recording medium on which the program according to claim 13 is recorded.

Images