JP4587123B2 - Image processing apparatus, image processing method, and image processing program - Google Patents

Description

  The present invention relates to an image processing apparatus, an image processing method, and an image processing program that can prevent information leakage of confidential documents.

  In recent years, with the spread of personal computers, printers, and copying machines, there has been a problem of information leakage due to unauthorized copying of confidential documents printed out.

  As a conventional technology for preventing and suppressing unauthorized copying of confidential documents, when printing confidential documents, copy prohibition information is embedded in the image and then printed out, and when copying, the original is read and embedded in the image. Multifunction devices having an illegal copy prohibition function are being studied, such as detecting copy prohibition information being detected and stopping normal copy operations when copy prohibition information is included (see, for example, Patent Document 1). .)

  Further, the illegal copy prohibition function has been developed, and two types of copy prohibition information in an image and copy permission condition information (for example, a personal identification number) for permitting copying under a specific condition when a confidential document is printed. Information is embedded and printed out, and at the time of copying, two types of information, copy-prohibited information and copy-permitted condition information, embedded in the image are detected from the scanned image to determine whether the copy-permitted condition is met. A multifunction device having an advanced illegal copy prohibition function is also considered, in which the copy operation is stopped when the copy permission condition is not met, but the copy operation is performed when the copy permission condition is met.

  Here, as an embedding method of copy prohibition information / copy permission condition information, for example, the following method has been proposed (for example, see Patent Document 2).

  That is, a background copy-forgery-inhibited pattern image having a comparatively low density is synthesized with a minute pattern on the entire background of the document image. The background copy-forgery-inhibited pattern image is composed of two regions, a latent image character region and a background region, and each region is composed of different micropatterns. The latent image character area is composed of a relatively small dot pattern, and the background area is composed of an array of two kinds of minute oblique line patterns.

  The two types of diagonal lines represent bits 0 and 1, respectively, and two-dimensional code images in which the two types of diagonal patterns are two-dimensional arrays of a predetermined size are repeatedly arranged adjacent to each other in the background portion. It has become.

  The copy permission condition information is embedded in this two-dimensional code. As copy prohibition information, the inside of the two-dimensional array is all embedded with a special code configured with a hatched pattern corresponding to bit 0, or the inside of the two-dimensional array is configured with a hatched pattern corresponding to bit 1 all.

  As another conventional example for preventing unauthorized copying of confidential documents, when printing confidential documents, information related to the user who performed the printing, date / time information, etc. are embedded and printed out. An image processing apparatus that analyzes a user, a client PC, a printer, and a date and time embedded in an image that has been read and read to identify an information leakage source has been studied. This function can be configured as an additional function of the conventional multifunction peripheral.

JP 2003-280469 A JP 2003-283790 A

  However, the conventional techniques have the following problems. First, in the conventional method of embedding copy prohibition information / copy permission condition information, copy prohibition information / copy permission condition information may not be detected during copying depending on the image content of the document.

  For example, in the case of a document in which the entire document background of a confidential document (electronic) is colored, the background copy-forgery-inhibited pattern image combined with the document background and the background (colored) of the original document are combined to overlap each other. Depending on the color and density, the oblique line pattern in the background tint pattern image cannot be detected, and as a result, the embedded copy prohibition information / copy permission condition information cannot be detected.

  In addition, when the confidential document to be printed is an image obtained by scanning an existing confidential document that has been printed with the background copy-forgery-inhibited pattern image printed, it is already combined with the background of the confidential document (scanned image) at the time of printing. An image in which a new background copy-forgery-inhibited pattern image is combined with the background copy-forgery-inhibited pattern image is printed out. In this case, two background copy-forgery-inhibited pattern images are superimposed on the printed image, but depending on the overlapping state of the hatched pattern, the information embedded in the original scan image and the new embedded image at the time of printing are used. Both of these information cannot be detected.

  In such a case, there is a problem that illegal copying may not be prohibited at the time of copying, even though the document has copy prohibition information embedded therein.

  The present invention has been made to solve such problems. That is, the present invention provides an image input means for inputting a document image, an embedded information acquisition means for acquiring information to be embedded in the document image, an information embedding means for embedding information input by the embedded information acquisition means, and the document image Output means for outputting the image, determination means for determining whether or not the document image input by the image input means is suitable for information embedding, and information embedding means if the determination means determines that it is suitable for information embedding And a control unit that controls to output a document image without information embedded from the image output unit when it is determined that the document image is not suitable. ing.

  In the present invention, it is determined whether or not the input document image is suitable for information embedding, and if it is suitable, the information is embedded and output, and if not suitable, the information is output without being embedded. Therefore, when information is embedded in the output document image, the embedded information can be reliably detected by reading the document image.

  Further, in the present invention, when a document image has a background, if the information to be embedded is affected by the background, the information is embedded after removing the background. As a result, even when the document image has a background, the embedded information can be reliably detected when the output document image is read.

  Therefore, according to the present invention, when embedding information such as copy prohibition information by printing or copying a confidential document, the information embedded in the image is surely received on the copier side regardless of the image content of the confidential document. Since it can be embedded so that it can be detected, it is possible to reliably prevent information leakage of confidential documents.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First embodiment]
Explanation of Overall System Configuration FIG. 1 is a schematic diagram showing a system configuration in the present invention. That is, this system is composed of a client PC (personal computer) 2 connected to the network 1 and a multifunction machine 3 having a plurality of functions such as a print function, a copy function, and a scan function. The image processing apparatus of the present invention is realized as the multifunction machine 3 shown in FIG.

Illustration 2 of a block diagram of the image processing apparatus is a block diagram showing the internal configuration of the MFP according to the first embodiment. The multifunction machine includes a scanner unit 31, an image processing unit 32, a printer unit 33, and an operation control unit 34. The scanner unit 31 reads a document placed on the platen and outputs the read image data to the image processing unit 32.

  The printer unit 33 prints and records the image data processed by the image processing unit 32 on paper. The image processing unit 32 processes the image data input from the scanner unit 31 and outputs the processed image data to the printer unit 33. Further, the image processing unit 32 performs drawing processing of print data (hereinafter referred to as “PDL data”) described in the print description language (PDL) input from the operation control unit 34 to generate document image data. The rendered document image data is output to the printer unit 33. Further, the image processing unit 32 generates background copy-forgery-inhibited pattern image data in accordance with an instruction from the operation control unit 34 and combines it with either the image data input from the scanner unit 31 or the drawn document image data, and then the printer unit 33. Output to.

  The operation control unit 34 includes a control unit 341 that performs overall control of the scanner unit 31, the image processing unit 32, and the printer unit 33, a network I / F (interface) 342, and a control panel 343 that is a user interface. The network I / F 342 transmits and receives data through the network. The control panel 343 includes an input / output device such as a touch panel display, and is a part that receives various operations and input of embedded information from the user.

Description of Outline of Copy / Print Function of Multifunction Device In addition to the normal copy, print, and scan functions, the multifunction device according to this embodiment has the following functions.
(1) Confidential document copy prohibition function When copying, copy prohibition information and copy permission condition information are detected from the scanned image. If copy prohibition information is detected, the copy permission condition is determined, and the copy permission condition is not met. In some cases, copying is prohibited.
(2) Function for creating copy-prohibited manuscript A function for creating the above-described confidential document (a manuscript with copy-prohibited information and copy-permitted condition information embedded) by copying / printing or copying.

  When printing, a confidential document is created by synthesizing a background pattern image with additional information embedded in the background of the document image, and when copying, a background pattern image with additional information embedded in the background of the read original image is synthesized. To create a confidential document.

Description of Operation for Creating Confidential Document There are two methods for creating a confidential document in which a background copy-forgery-inhibited pattern image is embedded.

First, the operation for creating a confidential document during printing will be described.
(1)... The control unit 341 receives PDL data via the network. The received PDL data is stored in a memory inside the control unit 341.
(2) The control unit 341 checks whether or not additional information (information embedded in the background copy-forgery-inhibited pattern image) is added to the header portion of the received PDL data (if added, add to (3)) If not, go to (4)).
(3)... When the additional information is added to the header, the control unit 341 extracts the additional information, notifies the background background pattern image generation unit 321 of the image processing unit 32, and performs background background pattern image generation processing. (Details will be described later). The background copy-forgery-inhibited pattern image data is generated as binary image data of 600 dpi. The generated background pattern image data is stored in the background pattern image buffer 322. Further, the control unit 341 controls the image composition unit 320 so as to synthesize the document image data and the background tint block image data. At this time, it is set to which of the YMCK planes of the document image the background copy-forgery-inhibited pattern image is to be combined.
(4)... The control unit 341 outputs the PDL data to the document image generation unit 323 to perform document image drawing / generation processing. The document image data is generated as, for example, 600 dpi, binary, YMCK full-color image data. The YMCK binary image drawing process is performed by a known method. The generated document image data is stored in the document image buffer 324.
(5)... The control unit 341 controls the copy prohibition information detection unit 325, the copy permission condition information detection unit 326, and the image determination unit 327 to start processing. The copy prohibition information detection unit 325, the copy permission condition information detection unit 326, and the image determination unit 327 respectively read document image data from the document image buffer 324, detect copy prohibition information, copy permission condition information, and the document image is a background. It is determined whether or not the copy-forgery-inhibited pattern image is suitable for composition (details will be described later). Each processing result is output to the control unit 341.
(6)... The control unit 341 controls to stop the printing operation when the copy prohibition information is detected. If the copy prohibition information is not detected, the printing operation is continued.
(7)... The control unit 341 is an image that is not suitable for embedding a new background copy-forgery-inhibited pattern image when the copy permission condition information is detected or the result of the image determination unit 327 is incompatible. It is determined that there is, and the image composition unit 320 is controlled not to perform the background tint block image composition process. If neither is detected, the image composition unit 320 is controlled to perform a background tint block image composition process.
(8)... The control unit 341 controls the printer unit 33 to start a print output operation. In synchronization with the operation of the printer unit 33, the image composition unit 320 reads document image data from the document image buffer 324 and outputs the document image data to the printer unit 33. If it is set to synthesize a background copy-forgery-inhibited pattern image, the background copy-forgery-inhibited pattern image data is read from the background copy-forgery-inhibited pattern image buffer 322 in synchronization with the reading of the document image data, and ORed to a predetermined color plane of the document image data. (OR) Composition is performed, and the composite image data is output to the printer unit 33.
(9)... The combined image data is printed and recorded on the paper in the printer unit 33 and output.

Here, the contents of the additional information are shown below.
(A) Copy prohibition information (whether or not to prohibit copying)
(B) ... Copy permission condition information (information for permitting copying if the conditions are met)
For example, a personal identification number, a user ID number that permits copying (employee number, etc.), a date and time for canceling copying prohibition, and a machine number of a copying machine that permits copying.
(C) Latent image information (information on latent image that floats when copied)
For example, latent image character string, font type, font size, latent image character string direction (angle), background tint pattern image color.

Next, an operation for creating a confidential document at the time of copying will be described.
(1)... The user selects a mode in which a background copy-forgery-inhibited pattern image is combined and copied from the control panel 343. At this time, additional information to be embedded in the background pattern image is also set. The setting contents are the same as the additional information at the time of printing. When the copy start button is pressed, the copy operation is started.
(2)... The control unit 341 notifies the background tint block image generation unit 321 of the additional information set from the control panel 343, and causes background tint block image generation processing (details will be described later). The background copy-forgery-inhibited pattern image data is generated as binary image data of 600 dpi. The generated background pattern image data is stored in the background pattern image buffer 322. In addition, the control unit 341 controls the image composition unit 320 to synthesize the document image data and the background pattern image data. At this time, it is set to which of the YMCK planes of the document image the background copy-forgery-inhibited pattern image is to be combined (performed based on information set from the control panel 343).
(3) The control unit 341 controls the scanner unit 31, the image processing unit 32, and the printer unit 33 so as to start a copying operation. The scanner unit 31 reads a document placed on a platen or an ADF (Auto Document Feeder).
(4)... The image data read by the scanner unit 31 is input to the scanned image processing unit 328, and image correction, color space conversion, and screen processing are performed. The processed image data is stored in the page buffer 329.
(5) In parallel with the above (4), the image data read by the scanner unit 31 is input to the copy prohibition information detection unit 325, the copy permission condition information detection unit 326, and the image determination unit 327, and the copy prohibition information, The copying permission condition information is detected, and whether or not the document image is suitable for the background tint block image composition is determined (details will be described later; the same as the processing at the time of printing). The detection result is output to the control unit 341.
(6)... The control unit 341 stops the copy operation when the copy prohibition information is detected. If the copy prohibition information is not detected, the printing operation is continued.
(7)... The control unit 341 determines that the image is not suitable for embedding a new background copy-forgery-inhibited pattern image when the copy permission condition information is detected or the result of the image determination unit 327 is incompatible. Judgment is performed and control is performed so that the image composition unit 320 does not perform composition processing of a new image. If neither is detected, the image composition unit 320 is controlled to perform a new image composition process.
(8)... When the control unit 341 is set to synthesize a new background pattern image, the image composition unit 320 receives the scan image data from the page buffer 329 and the background pattern image buffer 322. Data is read out in synchronization with each other, logical sum (OR) synthesis is performed on a predetermined color plane of the document image data, and the synthesized image data is output to the printer unit 33. If it is set not to synthesize a new background copy-forgery-inhibited pattern image, the scanned image data is read from the page buffer 329 and output to the printer unit 33 as it is.
(9)... The combined image data is printed and recorded on the paper in the printer unit 33 and output.

  A copy-prohibited manuscript is created by the background tint block image composition process described above. At this time, if a background copy-forgery-inhibited pattern image has already been combined with a document image to be printed or a document image to be copied, control is performed so that a new background copy-forgery-inhibited pattern image is not combined. This prevents the background copy-forgery-inhibited pattern image included in the document image from overlapping with the newly-composited background copy-forgery-inhibited image and prevents information embedded in both background copy-forgery-inhibited pattern images from being interfered with each other and cannot be detected. it can.

Explanation of Background Pattern Image Generation Processing FIG. 3 is a block diagram showing the internal configuration of the background pattern image generation unit. The operation of the background tint block image generator will be described. Additional information (copy prohibition information, condition information, and latent image information) is input to the background tint block image generation unit 321 from the control unit 341 (see FIG. 2). Among these, copy prohibition information and copy permission condition information are input to the additional information encoding unit 3211, and latent image information is input to the latent image generation unit 3212.

  The latent image generation unit 3212 generates a latent image based on the input latent image information. The latent image information is information indicating what kind of latent image character is embedded in the pattern image.Specifically, the latent image character string, font type, font size, and latent image character string direction ( Angle) and other information. Upon receiving the latent image information, the latent image generation unit 3212 draws a latent image character string in the specified direction with the specified font type and font size, and generates a binary latent image image. The generated latent image is output to the additional information encoding unit 3211.

  Here, the resolution of the latent image is a resolution obtained by dividing the resolution of the printer by the size of a pattern to be described later. For example, when the printer resolution is 600 dpi and the pattern size is 12 pixels × 12 pixels, the resolution of the latent image is 50 dpi.

  The additional information encoding unit 3211 encodes the input copy prohibition information and condition information. First, when the copy prohibition information indicates that a document that has been printed out is not to be copied by a copying machine, two types of copy prohibition codes shown in FIGS. 6A and 6B are generated. Here, the copy prohibition code shown in FIG. 6A is all bit 0 inside the code, and the copy prohibition code shown in FIG. is there. When the copy prohibition information is not input, or when it does not indicate that the document that has been printed out is not to be copied by the copying machine, the two types of codes shown in FIGS. 6A and 6B are generated. Not done.

  Next, when condition information is input, an error correction code is applied to the condition information to generate a condition code as shown in FIG. The code in FIG. 6C represents a bit string of the encoded condition information by the arrangement of bit 0 and bit 1. The outer periphery of the cord has a special bit pattern for facilitating the positioning of the cord.

  Next, a plurality of the generated codes are repeatedly arranged as shown in FIG. 7A to generate a pattern number array having the same size as the latent image. Here, the hatched rectangle in the figure is the copy prohibition code of FIG. 6A, the vertical hatched rectangle is the copy prohibition code of FIG. 6B, and the dot hatched rectangle is FIG. 6C. This is the condition code. If a copy prohibition code is not generated, a condition code is placed in the copy prohibition code portion in the figure. If the condition code is not generated, a copy prohibition code is placed in the condition code portion in the figure. At this time, the value of each element of the pattern number array is 0 or 1.

  Next, referring to the latent image, the pattern number of the element of the pattern number array corresponding to the coordinates of the black pixels in the latent image is changed to 2. If this is performed for all the black pixels in the latent image, the pattern number arrangement is such that the latent image characters are drawn with the pattern number 2 on the background in which the copy prohibition code and the condition code are arranged side by side. This state is shown in FIG. A black “COPY” portion in the figure indicates a portion in which the pattern array number is changed to “2”. The pattern number array is output to the pattern image generation unit 3213.

  The pattern image generation unit 3213 refers to each element of the input pattern number array, reads a pattern corresponding to the pattern number from the pattern storage unit 3214, and converts it into a pattern image, thereby generating a background pattern image. The generated background pattern image is stored in the background pattern image buffer 322 (see FIG. 2).

  4A and 4B are schematic diagrams showing examples of patterns stored in the pattern storage unit. FIG. 4A is a pattern corresponding to pattern number 0, FIG. 4B is a pattern corresponding to pattern number 1, and FIG. 4C is a pattern number. 2 is a pattern corresponding to 2. Here, the pattern number array corresponds to the resolution of the image obtained by dividing the printer resolution by the pattern size, and the pattern image generated based on this is generated by replacing one element of the pattern number array with one pattern. The generated pattern image matches the resolution of the printer. Further, the pattern image is an image in which a latent image character is converted into an isolated dot pattern by converting into a hatched pattern corresponding to the bit values of the copy prohibition code and the condition code.

  The pattern image generated in this way is stored in the background tint block image buffer 322 as a background tint block image, and is synthesized with the document image data in accordance with the processing described in the above-mentioned “operation when creating a confidential document during copying”. And printed out on paper.

  An example of a printed image is shown in FIG. 5A (for convenience of explanation, the document image shows an example of a pure white image having no image elements). FIG. 5C is an enlarged view of the area surrounded by the rectangle in FIG. FIG. 5B shows a copy output image when FIG. 5A is copied by a copying machine.

Description of Processing of Copy Prohibition Information Detection Unit Next, the operation of the copy prohibition information detection unit will be described with reference to FIG. Image data output from the scanner unit 31 (see FIG. 2) or the document image buffer 324 (see FIG. 2) is input to a grayscale conversion unit 3251, and after full color → grayscale conversion is performed, a binarization processing unit It is binarized by 3252.

  The binarized image data is input to the noise removal process 3253, and the noise removal process is performed. Specifically, a pixel block in which black pixels are connected is obtained, and each pixel of the pixel block whose size (number of connected pixels) is not within a predetermined range is replaced with a white pixel. The predetermined range is set to an appropriate range so that the hatched pattern is not deleted, and other patterns (isolated dot patterns, characters and figures in the document, etc.) are deleted.

  The noise-removed image data is input to the pattern detection unit 3254, where two types of oblique line pattern detection processing are performed, and the result is output as 1-pixel 2-bit image data. Specifically, the pattern shown in FIGS. 4A and 4B is applied at the position of each pixel in the image data, and detection is performed by template matching. Here, when the pattern (A) is detected, the pixel value 0 is output, when the pattern (B) is detected, the pixel value 1 is output, and when the pattern is not detected, the pixel value 2 is output.

  The image data output from the pattern detection processing unit 3254 is input to the blocking processing unit 3255. Here, the block size is set to a size smaller than half the size of the copy prohibition code and the condition code, and is set to a size such that one or more blocks are completely included in the code. The blocking processing unit 3255 divides the input image data into blocks of a predetermined size and outputs them to the number calculation unit 3256.

  The number calculation unit 3256 calculates the number of pixels having a pixel value 0 and the pixel having a pixel value 1 in the block, and outputs the result to the ratio calculation unit 3257. Further, the total is output to the determination processing unit 3258. The ratio calculation unit 3257 calculates the ratio of pixels with a pixel value of 0 and outputs the result to the determination processing unit 3258.

  The determination processing unit 3258 performs determination processing based on the total number input from the number calculation unit 3256 and the ratio input from the ratio calculation unit 3257.

  Here, when the inside of the block being processed is located inside the copy prohibition code of all bits 0, a diagonal line pattern corresponding to a predetermined number of bits 0 or more is detected in the block, and bit 1 Since the hatched pattern corresponding to is hardly detected, the ratio of the hatched pattern corresponding to bit 0 should be high and almost close to 1.0.

  If the block currently being processed is located inside the copy prohibition code of all bits 1, a hatched pattern corresponding to a predetermined number of bits 1 or more is detected in the block, and bit 0 is set. Since the corresponding diagonal pattern is hardly detected, the ratio of the diagonal pattern corresponding to bit 0 should be low and almost close to 0.0.

  Further, when the block being processed includes at least a part of the condition code, a diagonal line pattern corresponding to a plurality of bits 0 and a diagonal line pattern corresponding to a plurality of bits 1 are detected inside the block. The ratio of the hatched pattern corresponding to 1 should be much lower than 1.0 and much higher than 0.

  If the input image data is an image in which copy prohibition information is embedded, the inside of the block includes a copy prohibition code with all bits 0 and the block has a copy prohibition code with all 1 bits. There should be more than one embedded.

The following determination process is performed using the above characteristics.
If the total number> the first threshold value and the ratio> the second threshold value, the block is determined as the copy prohibition code 0.
If the total number> the first threshold value and (1-ratio)> the second threshold value, the block is determined to be the copy prohibition code 1.
In cases other than the above, it is determined that the block is not a copy prohibition code.

  The first threshold value is set by adding a margin to the number of theoretical patterns included in the block based on the block size and the pattern size. A value close to 1.0 is set as the second threshold (for example, the second threshold = 0.95).

  The determination processing unit 3258 separately counts the number of blocks determined as the copy prohibition code 0 and the number of blocks determined as the copy prohibition code 1. If the number of blocks determined as copy prohibition code 0 is equal to or greater than threshold 3, and the number of blocks determined as copy prohibition code 0 is equal to or greater than threshold 3, the image is determined to be a copy prohibited document, and the determination result is Output to the control unit.

  The above-mentioned copy prohibition information detection process does not need to accurately determine the pattern arrangement (bit string) in the code and perform the decoding process, and calculates the number and ratio of patterns in the block regardless of image skew or positional deviation. Since the amount of information is small (representing only the presence or absence of a copy prohibition code), the determination process can be performed in real time. In addition, since a copy-prohibited image is determined only when a predetermined number or more of two types of copy-prohibited codes are detected, even if a pattern similar to the copy-prohibited code is included in a normal image that is not a copy-prohibited image, an error is caused. Determination accuracy can be improved without determination.

Copy permission condition information detecting section of the processing described will now be explained with reference to FIG. 9, the operation of the condition information detection unit. Image data output from the scanner unit 31 (see FIG. 2) or the document image buffer 324 (see FIG. 2) is input to a grayscale conversion unit 3251, and after full color → grayscale conversion is performed, a binarization processing unit It is binarized by 3252.

  The binarized image data is input to the noise removal processing unit 3253, and noise removal processing is performed. The image data from which noise has been removed is input to the pattern detection unit 3254, where two types of oblique line pattern detection processing is performed, and the processing result image data is stored in the buffer memory 3265. In this image data, the pixel value at the position where the diagonal line pattern corresponding to bit 0 is detected is 0, the pixel value at the position where the diagonal line pattern corresponding to bit 1 is detected is 1, and other values are 2 The image data is 2 bits per pixel.

  The image data stored in the buffer memory 3265 is input to the skew angle detection processing unit 3266, and the skew angle is detected. Here, the skew angle of the input image data is obtained. As a specific method, Hough transform is performed on a pixel having only a pixel value of 0 or 1, and the peak of the projection distribution on the angle axis is obtained. The obtained skew angle is output to the code detection processing unit.

  Next, the image data stored in the buffer memory 3265 is read out and input to the code detection unit 3267 to detect a two-dimensional code. Specifically, the image is scanned along the obtained skew angle to extract a pixel value of 0 or 1 (corresponding to 0 or 1 of the bit). The sync code is found from the extracted bit sequence. The synchronization code is defined as a code in which the outer periphery of a rectangular area having a predetermined vertical and horizontal size is entirely composed of bits 1. A bit array surrounded by the synchronization code is a two-dimensional code (condition code). This bit array is rearranged into a one-dimensional bit string and output to the error correction decoding unit 3268.

  The error correction decoding unit 3268 performs a predetermined error correction decoding process on the input bit string and decodes it as condition information. The decrypted condition information is output to the control unit 341 (see FIG. 2).

Description of Process of Image Determination Unit Next, the operation of the image determination unit will be described with reference to FIG. Image data output from the scanner unit 31 or the document image buffer 324 is input to the gray scale conversion unit 3271 and the color extraction unit 3278. The gray scale conversion unit 3271 converts the input image (RGB or YMCK) to gray scale.

  The image data converted to grayscale is input to two binarization processing units 3272 and 3276, and binarized with a predetermined threshold value. The first binarization processing unit 3272 performs binarization for performing subsequent pattern detection processing.

  The binarized image data is input to the noise removal processing unit 3273, and noise removal processing is performed. The image data from which noise has been removed is input to the pattern detection processing unit 3274, where two types of oblique line pattern detection processing are performed, and the image data resulting from the processing is stored in the buffer memory. In this image data, the pixel value at the position where the diagonal line pattern corresponding to bit 0 is detected is 0, the pixel value at the position where the diagonal line pattern corresponding to bit 1 is detected is 1, and other values are 2 The image data is 2 bits per pixel.

  The number of oblique line patterns detected by the pattern detection processing unit 3274 is counted by the pattern count unit 3275, and the count result is output to the determination unit 3270.

  In parallel with the above processing, the image data output from the grayscale conversion unit 3271 is binarized by the second binarization processing unit 3276. The high density pixel count unit 3277 counts the number of black pixels in the binary image and outputs the count result to the determination unit 3270.

  In parallel with the above processing, the image data input to the image determination unit is input to the color extraction unit 3278 to extract pixels of a predetermined range of colors. The number of extracted pixels is counted by the specific color pixel counting unit 3279.

  The determination unit 3270 determines whether or not the input image is an image that is not suitable for synthesis of a new background tint block image based on the input pattern count result, high density pixel count result, and specific color pixel count result. Specifically, each count result is compared with a set threshold value, and if there is an image that is equal to or greater than the threshold value, it is determined that the input image is an image that is not suitable for synthesis of a new background pattern image. The determination result is output to the control unit 341 (see FIG. 2).

  Next, an operation for copying a confidential document created as described above will be described. The multifunction peripheral of this embodiment has two types of copy operation modes. One is a normal copy mode, and the other is a conditional copy mode. Different operations are performed depending on the set copy operation mode.

Description of Copy Prohibiting Operation in Normal Copy Mode First, the operation in the normal copy mode when copying a document original printed out as described above will be described.
(1) The scanner unit 31 reads an original placed on a platen or ADF (Auto Document Feeder).
(2) Image data read by the scanner unit 32 is input to the image processing unit, and image correction, color space conversion, and screen processing are performed. The processed image data is stored in the page buffer 329.
(3)... In parallel with the above (2), the image data read by the scanner unit 31 is input to the copy prohibition information detection unit 325 and the copy permission condition information detection unit 326. Detection and detection of the presence / absence of a background copy-forgery-inhibited pattern image are performed (details are the same as described above; the same processing as printing). The detection result is output to the control unit 341. The copy prohibition information detection unit 325 operates only in the normal copy mode, performs a copy prohibition code detection process described later from the image data, and outputs the detection result to the control unit 341. The copy permission condition information detection unit 326 operates only when the operation mode of the copying machine is set to the conditional copy mode by the control unit 341, and is set not to operate in the normal copy mode.
(4)... The control unit 341 stops the copy operation if the detection result input from the copy prohibition information detection unit 325 indicates that the copy prohibition code has been detected, and sends a message to that effect to the control panel 343. Display. On the other hand, if the detection result input from the copy prohibition information detection unit 325 indicates that the copy prohibition code is not detected, the copy operation is continued as follows.
(5)... The image data stored in the page buffer 329 is output as it is to the printing unit 33 via the image synthesis unit 320, and is printed and recorded on paper.

Description of Copy Operation in Conditional Copy Mode Next, the operation in the conditional copy mode will be described.
(1)... The user operates the control panel 343 of the multifunction peripheral to set the conditional copy mode. A screen for inputting a user ID and a password is displayed on the control panel 343, and the user inputs the user ID and the password. The controller 341 is notified that the conditional copy mode has been set, and the input user ID and personal identification number. The control unit 341 performs the following conditional copy operation.
(2) The scanner unit 31 reads a document placed on a platen or ADF (Auto Document Feeder).
(3) Image data read by the scanner unit 31 is input to the image processing unit 32, and image correction, color space conversion, and screen processing are performed. The processed image data is stored in the page buffer 329.
(4)... The image data output from the scanner unit 31 is output to the copy prohibition information detection unit 325 and the copy permission condition information detection unit 326 in parallel with the operation (3). The copy prohibition information detection unit 325 is set by the control unit 341 to operate only in the normal copy mode and not to operate in the conditional copy mode. The copy permission condition information detection unit 326 operates only when the operation mode of the copying machine is set to the conditional copy mode. The copy permission condition information detection unit 326 detects a condition code, which will be described later, from the image data, and decodes and detects the detected code. The read condition information is read and the condition information is output to the control unit. The condition information is information indicating the conditions for enabling copying of a document that has been printed out. The personal identification number, the user ID number that permits copying (employee number, etc.), the date and time when the copy prohibition is canceled, and copying is permitted. Includes the machine number of the copier, etc.
(5)... The control unit 341 compares the machine number permitted for copying included in the condition information with its own machine number stored in the ROM inside the control unit. If the machine number is included, the user ID and password entered from the control panel 343 are compared with the user ID and password contained in the copy permission condition information detection unit 326. When the user ID is included and the passwords match, the current date and time are read from the timer held in the control unit 341 and compared with the date and time when the copy prohibition is removed included in the condition information. . If the current date and time has passed the date and time when the copy prohibition is canceled, the copying operation as shown below is continued. Otherwise, the copy operation is stopped.
(6)... The image data stored in the page buffer 329 is output as it is to the printing unit 33 via the image synthesis unit 320, and is printed and recorded on paper.

[Second Embodiment]
In the second embodiment, a background copy-forgery-inhibited pattern image is detected from a scanned image, deleted as necessary, and then synthesized again.

  FIG. 11 is a block diagram illustrating an internal configuration of a multifunction peripheral according to the second embodiment. A difference from the first embodiment is that a background tint block image deletion unit 350 is added between the page buffer 328 and the image composition unit 320. In the present embodiment, copy prohibition information detection processing, condition information detection processing, and image determination processing are performed on document image data stored in the document image buffer 324 during printing, and image data read by the scanner unit 31 during copying. If any of them is detected, the background pattern image included in the image is deleted, and then a new background pattern image is synthesized.

Explanation of processing of background tint block image deletion unit Next, the operation of the condition information detection unit will be described with reference to FIG. First, image data output from the scanner unit 31 (see FIG. 11) or the document image buffer 324 (see FIG. 11) is input to the gray scale unit 351 and the color extraction unit 359. The gray scale conversion unit 351 converts the input image (RGB or YMCK) to gray scale.

  The image data converted to grayscale is input to two binarization processing units 352 and 358, and binarized with a predetermined threshold value. The first binarization processing unit 352 performs binarization for performing subsequent pattern detection processing.

  The binarized image data is input to the noise removal processing unit 353, and noise removal processing is performed. The image data from which the noise has been removed is input to the pattern detection processing unit 354, and two types of oblique line pattern detection processing are performed. When a pattern is detected, the result is output to the region signal generation unit 355, and a binary image having the same shape as the pattern detected at the position of the detected pattern is generated. The generated binary image becomes a region image (1) for image deletion. The generated region image is output to the selection unit 356.

  In parallel with the above processing, the image data output from the gray scale conversion unit 351 is binarized by the second binarization processing unit 358. This binarized pixel becomes a region image (2) for image deletion. The generated binary image is output to the selection unit 356.

  In parallel with the above processing, the image data input to the background tint block image deletion unit is input to the color extraction unit 359 to extract pixels of a predetermined range of colors. If it is a pixel in a predetermined range of color, a binary image having a pixel value “1”, otherwise a pixel value “0” is generated. This binary image becomes a region image (3) for image deletion. The generated binary image is output to the selection unit 356.

  The selection unit 356 receives the region image (1), the region image (2), and the region image (3) in parallel. The selection unit 356 receives a selection signal from a control unit (not shown), selects one of the three region signals according to the selection signal, and outputs the selected signal to the image deletion unit 357.

  The image deletion unit 357 receives input image data to the background tint block image deletion unit and the region image input from the selection unit 356. The image deletion unit 357 deletes the pixel of the input image corresponding to the pixel value “1” of the region signal (binary image) (replaces it with a white pixel).

  With the above processing, the pattern portion (or high-density background pixel portion or specific color pixel portion) of the background tint block image included in the background in the input image is deleted, so a new background tint block image can be created when printing or copying. When combining, the background pattern image that was originally included in the input image does not overlap, and the information embedded in the newly combined background pattern image can be reliably read from the printed image. Become.

  In each of the embodiments described above, based on the detection result of the oblique line pattern from the scan image or the print output image, the determination result of the density of the background pattern image, and the determination result of the specific color of the background pattern image, Although it is configured to control whether to synthesize a new background pattern image, it may be configured to determine whether to synthesize a background pattern image based on all three types of processing results. Alternatively, it may be configured to determine whether to synthesize the background tint block image based on only one or two types of processing results.

  As a specific example of the background tint block image density determination process, an example is given in which each pixel is compared with a predetermined threshold and the number of high density pixels is counted. It is also possible to detect the dot pattern, determine the density based on the size of the halftone dot pattern, and determine whether or not to synthesize a new background tint pattern image based on the result.

  The processing performed in each embodiment can be controlled by computer program processing. For example, in the first embodiment, a step of inputting a document image with the scanner unit 31, a step of receiving information for embedding in the document image from the control panel 343, and an image determination unit for determining whether the document image is suitable for information embedding. If it is determined in step 327 that the image determination unit 327 determines that the background pattern image is suitable, the background pattern image is synthesized with the document image. If it is determined that the image pattern is not suitable, the background pattern image is not synthesized. Steps in the control unit 341 that performs control output from the printer unit 33 can be realized by program processing.

  In the second embodiment, the step of inputting a document image by the scanner unit 31, the step of receiving information for embedding in the document image from the control panel 343, and the image determination unit determining whether the document image is suitable for information embedding. In step 327, if it is determined that the determination result in the image determination unit 327 is not suitable, the background image deletion unit 350 removes the background, and then the image composition unit 320 composes a new background pattern image. A step in the control unit 341 that performs control to output the image in the printer unit 33 by synthesizing the background copy-forgery-inhibited pattern image without removing the background when it is determined to be suitable is output by the printer unit 33 by program processing. be able to.

  According to the present invention, a document image to be printed or a background copy-forgery-inhibited pattern image in which information is embedded in the background of a document image to be copied is synthesized and printed out. It is determined whether or not the background copy-forgery-inhibited pattern image is originally included. If it is determined that the background copy-forgery-inhibited pattern image is included, control is performed so as not to synthesize a new background copy-forgery-inhibited pattern image. The information embedded in the background copy-forgery-inhibited pattern image included in the original document image or the original image can be reliably read from the obtained image.

  Also, in an image processing apparatus that synthesizes and outputs a background copy-forgery-inhibited pattern image in which information is embedded in the background of a document image to be printed or copied, a background copy-forgery-inhibited image is originally included in the document image or the original image. If it is determined that the background copy-forgery-inhibited pattern image is included, the newly generated information is obtained after removing the background copy-forgery-inhibited pattern image included in the original document image or the original image. Therefore, it is possible to reliably read newly embedded information from a printed or copied image.

It is a schematic diagram which shows the system configuration | structure in this invention. 1 is a block diagram illustrating an internal configuration of a multifunction machine according to a first embodiment. It is a block diagram which shows the internal structure of a background tint block image generation part. It is a schematic diagram which shows the example of a pattern. It is a schematic diagram which shows the example of a print output and a copy output. It is a schematic diagram explaining a code | cord | chord. It is a schematic diagram explaining a pattern number arrangement | sequence. It is a block diagram explaining a copy prohibition information detection part. It is a block diagram explaining a copy prohibition information detection part. It is a block diagram explaining an image determination part. It is a block diagram which shows the internal structure of the multifunctional device which concerns on 2nd Embodiment. It is a block diagram explaining a condition information detection part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Network, 2 ... Client PC, 3 ... Multifunction machine, 31 ... Scanner part, 32 ... Image processing part, 33 ... Printer part, 34 ... Operation control part

Claims (6)

An image input means for inputting a document image;
A background copy-forgery-inhibited pattern image removing unit that removes a background copy-forgery- inhibited pattern image that is included in the document image input by the image input unit and includes a pattern image in which a plurality of types of micropatterns having different shapes are arranged ;
Embedded information acquisition means for acquiring information embedded in the document image;
According to information input by the embedded information acquisition means, said generating a background pattern image, by combining the background pattern image the generated in the background of the document image, the information embedding means embeds information in the document image,
Image output means for outputting the document image;
Control means for controlling the information embedding means;
Have
The control means includes
When one or more types of minute patterns are detected from the input document image and the number of detected minute patterns is less than the threshold value, the background pattern image removal unit performs background pattern image removal. Control to embed information in a non-document image, and if the number of micropatterns is equal to or greater than a threshold value, control to embed information in the document image from which the background pattern image was removed by the background pattern image removal means. A featured image processing apparatus. The control means controls so as not to output the document image when copy prohibition information indicating prohibition of copying of the document image is detected from the minute pattern.
  The image processing apparatus according to claim 1. A first image showing a binary image in which a pixel value of a minute pattern that is not a removal target of each pixel in the input document image is a first pixel value and a pixel value of a minute pattern to be removed is a second pixel value. A first region image generation unit for generating a region image;
  A binary image in which the background value of each pixel in the input document image is a pixel value equal to or lower than a predetermined value as a first pixel value, and a pixel value whose background density is higher than the predetermined value is a second pixel value A second region image generation unit for generating a second region image to be shown;
  A pixel value in which the background color of each pixel in the input document image is in a predetermined range is defined as a first pixel value, and a pixel value in which the background color is out of the predetermined range is defined as a second pixel value. A third region image generation unit for generating a third region image indicating a binary image;
  Further comprising
  The background background pattern image removing means includes:
  Remove a pixel of a document image corresponding to a second pixel value of any one of the first region image, the second region image, and the third region image.
  The image processing apparatus according to claim 1. The control means includes
  When the background density of the input document image is detected and the background density is equal to or lower than a predetermined value, control is performed so that information is embedded in the document image that has not been subjected to background background image removal by the background background pattern image removal means. When the background density is larger than a predetermined value, control is performed so that information is embedded in the document image from which the background tint pattern image is removed by the background tint pattern image removing unit
  The image processing apparatus according to claim 1. The control means includes
  When the background color of the input document image is detected and the background color is within a predetermined range, information is embedded in the document image that has not been subjected to background background image removal by the background background pattern image removal means. If the background color is outside the predetermined range, control is performed so that information is embedded in the document image from which the background tint pattern image is removed by the background tint pattern image removing unit.
  The image processing apparatus according to claim 1. Inputting a document image;
A background copy-forgery-inhibited pattern image removal step for removing a background copy-forgery-inhibited pattern image that includes a pattern image that is included in the document image input in the input step and includes a plurality of types of micropatterns having different shapes; and
Obtaining embedding information for embedding in the document image;
An information embedding step for embedding information in the document image by generating the background copy-forgery-inhibited pattern image according to the acquired information, and combining the generated background copy-forgery-inhibited pattern image with a background of the document image;
If one or more types of minute patterns are detected from the input document image and the number of detected minute patterns is less than a threshold, the background embedding image removing step performs background processing by the information embedding step. Control is performed so that information is embedded in a document image that has not been subjected to background pattern image removal. When the number of detected micropatterns is equal to or greater than a threshold value, background background pattern image removal is performed in the background background pattern image removal step by the information embedding step. And a control step for controlling to embed information in the document image on which the image processing has been performed.

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