JP2006121569A - Information embedded region deciding apparatus, and printed matter issuing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information embedded region deciding apparatus and printed matter issuing apparatus in which information embedded in a document image is speedily and efficiently detected. <P>SOLUTION: The information embedded region deciding apparatus comprises a region deciding means (104) for deciding whether information is in a region in which dot patterns with discontinuity in an invisible form is embedded, in image regions of a document image generated by converting a document into an image. When the absolute value of a difference between pixel values of one or more pixels of interest in the document image and pixel values of pixels in the vicinity of the pixels of interest is a first threshold or more and the average value of pixel values of the pixels of interest is a second threshold or more, the region deciding means decides the region as a region wherein said dot patterns are embedded when the result of linear coupling of (1) the absolute value of the difference between the pixel values of the pixels of interest and the pixel values of pixels in the vicinity of the pixels of interest and (2) the average value of the pixel values of the pixels of interest is a third threshold or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information embedding area determination device that determines whether or not an information is embedded in an area, and a printed material issuing apparatus that can process a printed material in which information is embedded.

  Conventionally, “watermarks” that embed information such as information to prevent copying or forgery in images and document data, and confidential information in a form that is invisible to the human eye, have been saved and passed data It is premised on all being performed on an electronic medium, and information detection can be reliably performed because there is no deterioration or disappearance of information embedded by a watermark. Similarly, to prevent documents that are printed on paper media from being tampered with or copied, they are not visually unsightly and are not easily tampered with. There is known a method of embedding information such as secret information that can be embedded in a print document.

  In order to detect the information embedded in the print document, an image obtained by reading the print document in which the information is embedded by an input device such as a scanner is required. Information embedded in the print document can be detected from the image acquired by the input device.

JP 2001-218008 A

  By the way, as in the embodiment of Patent Document 1, an image obtained by reading with an input device such as a scanner is, for example, when the size of a document as a print document is smaller than the imaging surface of the input device, In many cases, information is not embedded in the entire document, and information is embedded in only a part of the information.

  In such a case, the image obtained by reading with the input device has many areas in which information by digital watermarking is not embedded, such as a blank area or a character area in which only characters are printed. End up. That is, a large amount of processing or processing time is required to detect information using the image obtained by the input device as it is.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved information embedding area capable of quickly and efficiently detecting information embedded in a document image. It is to provide a determination device and a printed matter issuing device.

  In order to solve the above-described problem, according to the first aspect of the present invention, information in an image region of a document image generated by image conversion of a document is in an invisible format, and discontinuity is reduced. A region determination unit that determines whether or not the dot pattern is embedded, and the region determination unit includes a pixel value of one or more target pixels of a document image and a pixel value in the vicinity of the target pixel; When the absolute value of the difference from the pixel value is greater than or equal to the first threshold and the value calculated from the average of the pixel values of each pixel of interest is greater than or equal to the second threshold, or (1) 1 or 2 or greater The absolute value of the difference between the pixel value of the pixel of interest and the pixel values in the vicinity of the pixel of interest; (2) a value calculated from the average of the pixel values of the respective pixels of interest, and the linear relationship between (1) and (2) If the result of combination is greater than or equal to the third threshold, the dot pattern Information embedding region determination unit and judging that it is a region that is embedded is provided. It should be noted that the dot pattern having discontinuity according to the present invention is represented by, for example, a type in which dots are written at predetermined intervals or irregular intervals, or discrete dots such as scattered from a collection of one dot. The type etc. which are made can be illustrated. Invisible information refers to information that cannot be discriminated or understood from the area even if the user looks at the area embedded with the dot pattern, for example.

  According to the present invention, the information embedding region determination device calculates a pixel value of a pixel (target pixel) to be determined and a pixel included in an image region of a document image, and a pixel value of a pixel in the vicinity of the target pixel. The absolute value obtained by the difference is not less than the first threshold as a value having discontinuity, and the value calculated from the average of the pixel values of the target pixel as the value indicating the density of the image is not less than the second threshold. Or (1) the absolute value of the difference between the pixel value of one or more target pixels and the pixel values near the target pixel, and (2) the value calculated from the average of the pixel values of the respective target pixels. Yes, if the result of the linear combination of (1) and (2) is greater than or equal to the third threshold, it is determined that the image area of the document image is an area in which the dot pattern is embedded. According to this configuration, when invisible information is detected from the area in which the dot pattern is embedded, the information detection is performed on the area in which the dot pattern is embedded without setting the entire image area of the document image as the detection target of the information. Therefore, the efficiency and speed of the information detection process can be increased.

  In order to solve the above-described problem, according to another aspect of the present invention, a predetermined symbol can be identified by a predetermined filter in an image area of a document image generated by image conversion of a document. A region determining unit that determines whether or not the dot pattern having continuity is embedded, the region determining unit including a pixel value of one or more target pixels of the document image and the target pixel; The absolute value of the difference from the pixel values of neighboring pixels is equal to or greater than the first threshold, and the value calculated from the average of the pixel values of each pixel of interest is equal to or greater than the second threshold as a value indicating the image density. Or (1) the absolute value of the difference between the pixel value of one or more target pixels and the pixel values near the target pixel, and (2) the value calculated from the average of the pixel values of each target pixel. , (1) and linear combination of (2) If the result is more than the third threshold value, the information and judging that the said dot pattern is embedded region embedded region judging device is provided.

  In order to solve the above-described problem, according to another aspect of the present invention, information in an image region of a document image generated by image conversion of a document is in an invisible format and has discontinuity. A region determination unit that determines whether or not the dot pattern is embedded, and the region determination unit divides the image area of the document image into a plurality of determination blocks and is included in the determination block Among the pixels, an average value of absolute values obtained by subtracting a pixel value of one or two or more target pixels and a pixel value of a pixel in the vicinity of the target pixel is equal to or more than a first threshold, and the pixel value of the target pixel When the value calculated from the average is greater than or equal to the second threshold as a value indicating the density of the image in the determination block, or (1) the pixel value of one or more target pixels and the pixel values near the target pixel The absolute value of the difference between (2 It is a value calculated from the average of the pixel values of each pixel of interest, and if the result of the linear combination of (1) and (2) is greater than or equal to the third threshold value, it is determined that the region is an area where a dot pattern is embedded An information embedding area determination device is provided.

  According to the present invention, the information embedding area determination device divides an image area of a document image into a plurality of determination blocks, and for each determination block, a pixel that is included in the determination block and is a determination target (target pixel) The average value of the absolute values obtained by subtracting the pixel value of the pixel and the pixel value of the pixel in the vicinity of the target pixel is not less than the first threshold as a value having discontinuity, and indicates the density of the image When the value calculated from the average of the pixel values of the target pixel is equal to or greater than the second threshold, or (1) the absolute value of the difference between the pixel value of one or more target pixels and the pixel values near the target pixel , (2) is a value calculated from the average of the pixel values of each pixel of interest, and if the result of linear combination of (1) and (2) is greater than or equal to the third threshold, the image area of the decision block is It is an area where the dot pattern is embedded Judges. According to this configuration, when invisible information is detected from the area in which the dot pattern is embedded, the dot pattern is embedded in each determination block without setting the entire image area of the document image as the detection target of the information. Therefore, it is only necessary to detect information about the determination block determined to be a region, so that the efficiency and speed of the information detection process can be improved.

  In order to solve the above-described problem, according to another aspect of the present invention, a predetermined symbol can be identified by a predetermined filter in an image area of a document image generated by image conversion of a document. A region determination unit that determines whether or not the dot pattern having continuity is embedded; the region determination unit divides the image region of the document image into a plurality of determination blocks; Among the included pixels, an average value of absolute values obtained by subtracting a pixel value of one or two or more target pixels and a pixel value of a pixel in the vicinity of the target pixel is equal to or more than a first threshold, and the pixel value of the target pixel When the value calculated from the average of the values is greater than or equal to the second threshold as a value indicating the density of the image in the determination block, or (1) the pixel value of one or more target pixels and the pixel values near the target pixel Difference from (2) is a value calculated from the average of the pixel values of each pixel of interest, and if the result of the linear combination of (1) and (2) is greater than or equal to the third threshold, a dot pattern is embedded An information embedding region determination device is provided that determines that the region is a region that has been recorded.

  In order to solve the above-described problem, according to another aspect of the present invention, the region determination unit determines whether or not the dot pattern is embedded in an image region in the document image. You may comprise so that the presence position of the area | region where the dot pattern was embedded may be detected.

  The area determination means determines, for each determination block, whether or not the image area of the determination block is an area embedded with a dot pattern, whereby an area in which the dot pattern in the image area in the document image is embedded The present position may be detected. With such a configuration, by detecting the presence position of the area in which the dot pattern is embedded, the information detection process may be executed for the detected position, and the information detection process can be made more efficient and faster.

  The area determination unit may be configured to obtain an absolute value of a difference between a pixel value of a target pixel and a pixel value of a pixel near the target pixel by at least an XOR operation, a bit shift operation, or an AND operation. With this configuration, since the absolute value can be obtained by a logical operation that can be processed at a very high speed, the determination process of whether or not the dot pattern is embedded is processed at a very high speed. Can do.

  You may comprise so that the area | region where the said dot pattern was embedded may be a visually recognizable figure.

  Further, the pixel in the vicinity of the target pixel may be configured to be at least one of the eight adjacent pixels adjacent to the target pixel. With such a configuration, for example, when the absolute value of the difference between the pixel value of the target pixel and the pixel values of the pixels near the target pixel is obtained by a logical operation, the bit string including the target pixel in the document image or the Since it is only necessary to perform a logical operation on the bit string and the upper and lower bit strings adjacent to the bit string, the processing efficiency and the processing speed can be improved.

  The area determination means obtains an absolute value obtained by subtracting a pixel value of the target pixel and a pixel value of the pixel adjacent to the left of the target pixel, and calculates a pixel value of the target pixel and a pixel value of the upper adjacent pixel of the target pixel. It may be configured to add to the difference absolute value and obtain an average value of the added absolute value. With this configuration, it is possible to maximize the speed of the calculation process for obtaining the average value for determining whether or not the dot pattern is embedded information.

  In order to solve the above-described problem, according to another aspect of the present invention, an image input unit that reads a document and converts it into an image; and an image output unit that prints or electronically outputs the document image after the image conversion. A region determination unit that determines whether or not there is a region in which a dot pattern having discontinuity is embedded in an image region of the document image in which information can be visually confirmed; and a dot pattern by the region determination unit If it is determined that there is an area in which the dot pattern is embedded, information detection means for detecting information by reading the area in which the dot pattern is embedded; and information detected by the information detection means prohibits copying of the document. Output control means for stopping image output by the image output means when the document copy prohibition information is indicated, the area determination means includes a plurality of image areas of the document image. Dividing into judgment blocks, out of the pixels included in the judgment block, the absolute value obtained by subtracting the pixel value of one or more target pixels and the pixel values of pixels in the vicinity of the target pixel is added, and the addition is performed. When the average value of the absolute values is greater than or equal to the first threshold and the value calculated from the average of the pixel values of the target pixel is greater than or equal to the second threshold, or (1) one or more of the target pixels An absolute value of a difference between a pixel value and a pixel value in the vicinity of the target pixel, (2) a value calculated from an average of the pixel values of each target pixel, and the result of the linear combination of (1) and (2) is When the value is equal to or greater than the third threshold value, a printed matter issuing apparatus is provided in which it is determined that a document image includes an area in which a dot pattern is embedded.

  According to the present invention, the area determination unit provided in the printed matter issuing apparatus divides the image area of the document image into a plurality of determination blocks, and for each determination block, the pixels included in the determination block and the pixels to be determined ( The average value of absolute values obtained by subtracting the pixel value of the pixel of interest) and the pixel values of the pixels in the vicinity of the pixel of interest is not less than the first threshold as a value having discontinuity, and the image density When the value calculated from the average of the pixel values of the pixel of interest is equal to or greater than the second threshold, or (1) the difference between the pixel value of one or two or more pixels of interest and the pixel values in the vicinity of the pixel of interest (2) is a value calculated from the average of the pixel values of each pixel of interest, and if the result of the linear combination of (1) and (2) is greater than or equal to the third threshold, There is an area where the above dot pattern is embedded It determines that. According to such a configuration, if the information detected from the area where the dot pattern is embedded is copy prohibition information meaning copy prohibition even in a part of the area, the output process of printing or electronic data is quickly stopped. If there is no area in which the dot pattern is embedded, it is not necessary to execute the information detection process, and the output process can be executed quickly and efficiently.

  In order to solve the above-described problems, according to another aspect of the present invention, an image input unit that reads a document and converts it into an image; an image output unit that prints or electronically outputs the converted document image; An area determination unit that determines whether or not there is an area in which a dot pattern having discontinuity is embedded in an image area of a document image in which information can be visually confirmed; and the dot pattern is embedded by the area determination unit An information detection means for detecting information by reading the area in which the dot pattern is embedded; and a document whose information detected by the information detection means indicates that copying of the document is prohibited. Output control means for stopping image output by the image output means when the copy prohibition information is provided, and the area determination means determines a plurality of image areas of the document image. Divide into blocks, and add the absolute value that is the difference between the pixel value of one or more pixels of interest and the pixel values of the pixels in the vicinity of the pixel of interest among the pixels included in the judgment block. When the average value is greater than or equal to the first threshold and the value calculated from the average of the pixel values of the target pixel is greater than or equal to the second threshold, or (1) the pixel value of one or more target pixels And the absolute value of the difference from the pixel value in the vicinity of the target pixel, (2) a value calculated from the average of the pixel values of each target pixel, and the result of the linear combination of (1) and (2) is the third Is equal to or greater than the threshold value, the image area of the determination block is determined to be an area in which the dot pattern is embedded, and the number of determination blocks determined to be the area in which the dot pattern is embedded is a fourth threshold value. In the above case, the character image Ttopatan printed matter issuing apparatus characterized by is determined that the region buried there is provided.

  According to the present invention, when the number of determination blocks determined to be an area in which the dot pattern is embedded is equal to or greater than the fourth threshold, the area determination unit provided in the printed matter issuing apparatus includes a document image at that time. , It is determined that there is an area in which the dot pattern is embedded. According to such a configuration, it is not always necessary to determine whether or not the dot pattern is embedded in all the determination blocks, so that it is possible to quickly determine whether or not there is an area in which the dot pattern is embedded in the document image. be able to. Furthermore, if the information detected from the area where the dot pattern is embedded is copy prohibition information that means copy prohibition, the output processing of printing or electronic data can be stopped quickly, and the dot pattern is embedded. If there is no such area, it is not necessary to execute the information detection process, so that the output process can be executed quickly and efficiently.

  The area in which the dot pattern is embedded may be configured to be a visually visible figure, and the area determination means may calculate the absolute difference between the pixel value of the target pixel and the pixel values of pixels in the vicinity of the target pixel. The value may be obtained by at least an XOR operation, a bit shift operation, or an AND operation.

  The pixel in the vicinity of the target pixel may be configured to be at least one of the eight adjacent pixels adjacent to the target pixel, and the region determination unit may further determine the pixel value of the target pixel and the left of the target pixel. The absolute value obtained by subtracting the pixel value of the adjacent pixel is added to the absolute value obtained by subtracting the pixel value of the target pixel and the pixel value of the adjacent pixel above the target pixel, and an average value of the added absolute values is obtained. You may comprise so that it may require | require.

  As described above, according to the present invention, by determining whether an image area in a document image is an area embedded with a dot pattern, the position of the area in which the dot pattern is embedded in the document image. Can be detected and the aperture information detection process can be executed on the area, so that the information detection process can be made more efficient and faster. In addition, since the determination is based on the dot discontinuity and the degree of image density, it is possible to perform a determination process with higher accuracy than the determination of only the image density degree.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, components having substantially the same functions and configurations are denoted by the same reference numerals, and redundant description is omitted.

  First, an information embedding area determination apparatus 100 according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing a schematic configuration of an information embedding area determination device 100 according to the first embodiment.

  As shown in FIG. 1, an information embedding area determination apparatus 100 according to the first embodiment includes, for example, a document reading unit (information reading unit) 102, an information area determination unit (area determination unit) 104, and information detection. Part 105.

The manuscript 101 is a document, document, figure / image, form, or the like that is subject to image conversion by the manuscript reading unit 102 printed on paper or the like. Further, for example, in a document (information embedded document) 101 in which information is embedded by printing a dot pattern on a paper medium or the like, normal characters or the like are printed on the document 101, and a digital watermark technique or the like is printed on the printed surface. In this way, invisible information such as confidential information is recorded. The invisible information refers to, for example, information that cannot be discriminated or understood from the area even if the user looks at the area embedded with the dot pattern. In order to embed invisible information in the original 101, for example, the following technique for embedding information in a printed material can be used.
Japanese Patent Laid-Open No. 2003-101762 “Digital watermark embedding device, digital watermark detection device, digital watermark embedding method, and digital watermark detection method” (Oki Electric Industry Co., Ltd., Patent Document 2)
As an example, the technique described in Japanese Patent Application Laid-Open No. 2003-101762 will be described. Information that cannot be viewed is generated by the watermark image forming unit. The watermark image forming unit digitizes the information to be embedded in the printed material and converts it into a numerical value (N is a natural number of 2 or more. The encoded bit string is referred to as a “code word”). Each symbol of the code word is assigned to a dot pattern prepared in advance. A dot pattern represents a wave having an arbitrary wavelength and direction, an array of dots having discontinuity, and the like by an arrangement of dots (black pixels), and a predetermined symbol is identified by a predetermined filter. be able to. In the document 101 of the present embodiment, it is possible to embed invisible information generated by the watermark image forming unit disclosed in Patent Document 2. Note that the information generated by the watermark image forming unit disclosed in Patent Document 2 is merely an example, and it goes without saying that other techniques may be adopted. Moreover, as said filter, a Gabor filter etc. can be illustrated, for example.

  The information embedded in the document 101 according to the present embodiment will be described by taking a case where information is embedded in the document 101 by printing a dot pattern as an example, but is not limited to this example. For example, information may be embedded in the original 101 using a digital watermark technique.

  Further, the dot pattern will be described in more detail. The dot pattern is a wave having an arbitrary wavelength and direction according to the arrangement of dots (black pixels), an array of dots having discontinuities, a discrete or random dot. This is a representation of the arrangement of

  The size when these dot patterns are printed on the paper surface depends on the resolution of information to be embedded such as a watermark image. For example, the information to be embedded is 600 dpi (dot per inch). If it is an image of the number of dots), the width and height of the dot pattern is 12/600 = 0.02 (inch) on the printed document.

  Hereinafter, a rectangle having a width and a height of Sw and Sh is referred to as a dot pattern as one signal unit. There are several types of dot patterns as shown below. In the first dot pattern, the distance between dots is dense in the direction of arctan (3) (arctan is an inverse function of tan) with respect to the horizontal axis, and the wave propagation direction is arctan (-1/3). . Hereinafter, this first dot pattern is referred to as pattern A. Next, in the second dot pattern, the distance between the dots is dense in the direction of arctan (−3) with respect to the horizontal axis, and the wave propagation direction is arctan (1/3). Hereinafter, this second dot pattern is referred to as pattern B.

  By assigning a symbol after the code to the dot pattern and embedding the dot pattern in an image such as a document image (document image), information such as copy prohibition information and confidential information can be embedded in the image. In the present embodiment, symbol 0 is assigned to the dot pattern represented by pattern A, and symbol 1 is assigned to the dot pattern represented by pattern B. These are also called symbol patterns.

  In addition to the patterns A and B, the dot pattern can be exemplified. For example, as a third dot pattern, the distance between dots is dense in the direction of arctan (1/3) with respect to the horizontal axis, and the wave propagation direction is arctan (-3). Hereinafter, this dot pattern is referred to as pattern C.

  Further, in the fourth dot pattern, the distance between the dots is dense in the direction of arctan (−1/3) with respect to the horizontal axis, and the wave propagation direction is arctan (3). Hereinafter, this dot pattern is referred to as a pattern D. In the fifth dot pattern, the distance between the dots is dense in the direction of arctan (1) with respect to the horizontal axis, and the propagation direction of the wave is arctan (−1). In the fifth dot pattern, it can be considered that the distance between the dots is dense in the direction of arctan (−1) with respect to the horizontal axis, and the wave propagation direction is arctan (1). Hereinafter, this dot pattern is referred to as a pattern E.

  In this way, in addition to the previously assigned combinations, there can be a plurality of types of dot pattern combinations to which symbols 0 and 1 are assigned, so it is important to keep secret which dot pattern is assigned to which symbol. It is also possible to make it impossible to easily decode a dot pattern in which three parties (illegal persons) are embedded.

  Information such as confidential information can be embedded by combining a plurality of dot patterns such as the patterns A to E, adding symbols corresponding to the dot patterns, and embedding them in a document image or the like.

  Furthermore, as shown in FIG. 2, when a dot pattern embedded in a document image or the like is output as a document 101 to a printed matter such as paper, a combination of a plurality of dot patterns is printed and, for example, “A” shown in FIG. Ordinary characters, graphics, or symbols such as In addition, although the case where the character was printed on the dot pattern concerning this Embodiment was mentioned as an example, it was not limited to this example, for example, it can implement even when nothing is printed on the dot pattern It is. FIG. 2 is an explanatory diagram in which a part of the area where the dot pattern is embedded in the document 101 is enlarged.

  Further, as an example of the dot pattern, since the number of dots in one pattern is all equal, by arranging these patterns without a gap, the apparent shade of an image such as a watermark image becomes uniform. Therefore, on the printed paper, a visible graphic or image such as a gray image having a single density appears to be embedded as a background.

  In order to produce such an effect, for example, the pattern E is defined as a background pattern (dot pattern to which no symbol is assigned), and this is arranged without any gap as the background of the watermark image, and the symbol pattern (pattern A, pattern B) Is embedded in the watermark image, the background unit (unit E) and the symbol pattern (pattern A, pattern B) at the position to be embedded are exchanged.

  Further, the present invention is not limited to the above, and a pattern EA obtained by combining a part of the pattern E shown in the upper left of FIG. 3 and the pattern A and a pattern EB obtained by combining a part of the pattern E shown in the upper right of FIG. The pattern EA or the pattern EB may be arranged in a tile shape without a gap. Similarly, a pattern EC by a combination of a part of pattern E and pattern C shown in the lower left of FIG. 3 and a pattern ED by a combination of part of pattern E and pattern D are newly generated. It can also be implemented by arranging the tiles without gaps. Furthermore, the present invention can be implemented even when the pattern EA, pattern EB, pattern EC, and pattern ED are arranged.

  Next, the document reading unit 102 shown in FIG. 1 reads the document 101 and generates a document image 103. The document reading unit 102 is an input device such as a scanner, and takes in the document 101 printed on paper as a multi-value gradation monochrome, gray image or the like. The document image 103 is a black and white binary image, and includes white pixels (pixels having a value of 1) or black pixels (pixels having a value of 0), but is not limited to such an example.

  The information area determination unit 104 detects where the information embedding area exists by determining an area in the document image 103 in which information is embedded by a dot pattern (hereinafter, information embedding area). To do. Information detection processing for detecting information from the information embedding area by the information detection unit 105 is performed on the area determined to be the information embedding area by the information area determination unit 104.

  The information detection unit 105 is a functional unit that performs processing for restoring information embedded from the information embedding area 304 in the image area. When the information generation function for embedding in the document 101 is realized by the watermark image forming unit disclosed in Patent Document 2 in the information embedding area determination apparatus 100, the function of the information detection unit 105 is also disclosed in Patent Document 2. It can be realized by the disclosed watermark detection unit. That is, the image in which the information formed by the watermark image forming unit is embedded is formed by a dot pattern that expresses a wave having an arbitrary wavelength and direction by an array of dots (black pixels), for example. The dot pattern can identify a predetermined symbol by a predetermined filter. In this way, the information detection unit 105 can perform processing for restoring information from an image. Note that the watermark detection unit disclosed in Patent Document 2 is merely an example for realizing the function of the information detection unit 105, and it goes without saying that other techniques may be employed.

  Next, the document image 103 according to the first embodiment will be described with reference to FIG. FIG. 4 is an explanatory diagram showing an outline of a document image according to the first embodiment.

  When the size of the document 101 is smaller than the imaging surface of the document reading unit 102, a blank area 302 exists around the edge of the document image 301 in the document image 301 as shown in FIG. 4. In addition, since information such as confidential information is not always recorded on the entire surface of the document, for example, an area 303 containing only normal characters or symbols exists. As described above, the area (information embedding area) 304 in which information is recorded is only a part of the document image 301. However, the present invention is not limited to this example, and the information embedding area 304 exists on the entire surface of the document image 103. You may do it.

  Next, an information embedding area determination process by the information area determination unit according to the first embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing an outline of the determination process of the information embedding area according to the first embodiment.

  As shown in FIG. 5, in the information embedding area determination process according to the first embodiment, first, the information area determination unit 104 acquires the document image 103 (S201). The document image 103 is image data obtained by converting the image from the document 101 by the document reading unit 102.

  Next, the information area determination unit 104 sets a determination block 401 for the document image 103 as shown in FIG. 6 (S202). The determination block 401 is an area having a sufficiently small size with respect to the size of the document image 103. Here, the determination block 401 is a rectangular area as shown in FIG. However, the shape of the determination block 401 according to the present embodiment is not limited to a rectangle, and can be implemented in any shape.

  It is determined for each determination block 401 whether the information is recorded (an information embedding area 304).

  Whether or not the information embedding area 304 according to the present embodiment is determined may be determined by slightly shifting the position of the determination block 401 vertically and horizontally as shown in FIG. As shown in FIG. 6, after the document image 103 is divided in advance for each size of the determination block 401, it may be determined whether each determination block 401 is the information embedding area 304 or not.

  Next, in order to determine whether or not it is the information embedding area 304, the information area determination unit 104 calculates an image feature in the determination block 401 (S203). Thereafter, whether or not the determination block 401 is the information embedding area 304 is determined based on the result of the image feature calculation processing in S203.

  The image feature calculation process (S203) in the determination block 401 by the information area determination unit 104 will be described. The document image 103 in the image feature calculation process (S203) will be described by taking a binary image composed of white and black as an example. In addition, it is assumed that characters and background patterns included in the original image 103 are black pixels (pixel value is 0), and a plain background is white pixels (pixel value is 1).

  In the image feature calculation processing (S203) of the document image according to the first embodiment, a discontinuity scale that mainly indicates the degree of dot discontinuity in the document image 103 and the image density (density) in the document image. The characteristics of the original image are judged by two scales of density scales indicating the degree of

  The degree of discontinuity can be determined based on the number of discontinuities of each pixel in the determination block 401. Here, as shown in FIG. 8, the discontinuous number is obtained by adding the absolute value of the difference between the target pixel and at least one of the adjacent pixels 1 to 8 adjacent to the target pixel and the target pixel. It is an added value. Note that the pixel of interest is, for example, a pixel that is included in the image area of the document image 103 and that is subject to determination as to whether or not it is the information embedding area 304.

  The number of discontinuities according to the first embodiment will be described with reference to FIG. FIG. 9 is an explanatory diagram illustrating an outline of the discontinuity number calculation process according to the first embodiment.

  As shown in FIG. 9, when the discontinuous number calculation process is performed based on two pixels of the adjacent pixel 2 and the adjacent pixel 4, the discontinuous number is calculated based on the pixel value of the adjacent pixel 2 and the target pixel. This is an added value obtained by adding the absolute values of the difference between the pixel values and the difference between the pixel value of the adjacent pixel 4 and the pixel value of the target pixel. In the above case, the number of discontinuities of each pixel is obtained as shown in Equation 1 below.

  Number of discontinuities = | pixel value of target pixel−pixel value of adjacent pixel 2 | + | pixel value of target pixel−pixel value of adjacent pixel 4 |

  In the above formula 1, for example, | pixel value of target pixel−pixel value of adjacent pixel 4 | is an absolute value of “pixel value of target pixel−pixel value of adjacent pixel 4”.

  In the discontinuous number of each pixel (pixel 801 to pixel 804) shown in FIG. 9, when the discontinuous number of each pixel (pixel 801 to pixel 804) is obtained according to the above equation 1, the discontinuous number of each pixel is as follows: Is calculated as follows.

  Since the pixel 801 has the pixel 801 as the target pixel, the pixel value of the target pixel is “1”. When the pixel 801 is the target pixel, the pixel value of the adjacent pixel 2 is “1”. Further, the pixel value of the adjacent pixel 4 is “1”. From the above, according to Equation 1, the number of discontinuities of the pixel 801 is “0”.

  The discontinuity of the pixel 802 is that the pixel value of the target pixel is “0” because the pixel 802 is the target pixel. If the pixel 802 is the target pixel, the pixel value of the adjacent pixel 2 is “1”. Further, the pixel value of the adjacent pixel 4 is “1”. From the above, the number of discontinuities of the pixel 802 is “2” from Equation 1 above.

  In addition, since the pixel 803 has the pixel 803 as the target pixel, the pixel value of the target pixel is “0”, and when the pixel 803 is the target pixel, the pixel value of the adjacent pixel 2 is “1”. Further, the pixel value of the adjacent pixel 4 is “0”. From the above, the number of discontinuities of the pixel 803 is “1” from the above equation 1.

  Further, the discontinuous number of the pixels 804 is that the pixel value of the target pixel is “1” because the pixel 804 is the target pixel. When the pixel 804 is the target pixel, the pixel value of the adjacent pixel 2 is “1”. Further, the pixel value of the adjacent pixel 4 is “0”. From the above, the number of discontinuities of the pixel 803 is “1” from the above equation 1.

  From the above, the discontinuous number of each pixel (pixel 801 to pixel 804) is obtained. Furthermore, the discontinuity scale is a value obtained by dividing the total value of the number of discontinuities of each pixel in the determination block 401 by the number of pixels obtained by calculating the number of discontinuities, but is not limited to such an example.

  For example, in the discontinuity scale shown in FIG. 9, since the determination block 401 is composed of the pixels 801 to 804, the total number of discontinuities of the pixels 801 to 804 is “4”. Since the number of pixels for which the number is calculated is “4”, the discontinuity measure is obtained as “1”.

  Up to this point, the processing for calculating the number of discontinuities of each pixel according to the first embodiment has been described with reference to FIG. 9, but as a modified example, the number of discontinuities can be calculated efficiently and at high speed. A process that can be performed will be described below with reference to FIG.

  For example, when the original image is in the bitmap (BMP) format in which 8 pixels are packed into one byte, the calculation of the number of discontinuities is XOR (exclusive OR) and bit shift (division by 2 and multiplication by 2). ) Can be calculated.

  As shown in FIG. 10, an image in the bitmap format has a bit string of one row in which 8 pixels are packed in one byte as B (x, y), and a bit string in the immediately preceding row as B (x, y−1). ), And the bit string in the immediately following row is B (x, y + 1).

  In the above case, the absolute value of the difference between the pixel of interest for obtaining the number of discontinuities and the adjacent pixels 1 to 8 is obtained by the following equation. [Xor] indicates an XOR operation, and [and] indicates an AND operation. Also, 0x indicates that the value is a hexadecimal number.

(Absolute value of difference between target pixel and adjacent pixel 1)
(B (x, y) [xor] (B (x, y-1) / 2)) [and] 0xfe (Expression 2)

(Absolute value of difference between target pixel and adjacent pixel 2)
B (x, y) [xor] B (x, y-1) (Formula 3)

(Absolute value of difference between target pixel and adjacent pixel 3)
(B (x, y) [xor] (B (x, y-1) x 2)) [and] 0x7f (Expression 4)

(Absolute value of difference between target pixel and adjacent pixel 4)
(B (x, y) [xor] (B (x, y) / 2)) [and] 0xfe (Expression 5)

(Absolute value of difference between target pixel and adjacent pixel 5)
(B (x, y) [xor] (B (x, y-1) x 2)) [and] 0x7f (Expression 6)

(Absolute value of difference between target pixel and adjacent pixel 6)
(B (x, y) [xor] (B (x, y + 1) / 2)) [and] 0xfe (Expression 7)

(Absolute value of difference between target pixel and adjacent pixel 7)
B (x, y) [xor] B (x, y + 1) (Expression 8)

(Absolute value of difference between target pixel and adjacent pixel 8)
(B (x, y) [xor] (B (x, y + 1) × 2)) [and] 0x7f (Equation 9)
The numerical value of the first bit (least significant bit) of the calculation result obtained by each of the equations 2 to 9 is the absolute value of the difference between the pixel of interest and the adjacent pixel.

  Furthermore, for example, by adding all the numerical values of the first bit obtained by the above formulas 2 to 9, it is possible to obtain the addition value of the absolute value of the difference from the target pixel when the adjacent pixels are 8 pixels. . That is, the number of discontinuities when the number of adjacent pixels is 8 can be obtained.

  As described above, when calculating the number of discontinuities, it is only necessary to perform a logical operation process on the bit string of a certain row and the bit string of the immediately preceding row or the immediately succeeding row. The processing can be executed at a much higher speed and efficiency than the processing of performing a complex logical operation such as performing a logical operation on the result value and another bit string.

  Next, a density scale that is a scale for determining another feature will be described. The density scale calculates the number of discontinuities in the determination block 401, and indicates the ratio of the number of black pixels.

  In the image feature calculation process (S203) according to the first embodiment, the case where the document image is a binary image composed of white and black has been described as an example. However, the present invention is not limited to this example. For example, even if the document image is a gray image (grayscale image), it can be implemented by binarizing with an appropriate value.

  Further, in the image feature calculation processing (S203) according to the first embodiment, the case where the absolute value is obtained from the target pixel and the adjacent pixel is described as an example in order to obtain the number of discontinuities. However, the present invention is not limited to this. For example, the present invention can also be performed when an absolute value is obtained from a pixel of interest and a pixel near the pixel of interest such as a pixel two pixels away from the pixel of interest.

  When the image feature calculation process (S203) by the information area determination unit 104 is performed using the determination block 401, next, an image in the determination block 401 area obtained in the image feature calculation process (S203) is checked. Based on the continuity scale and the density scale, it is determined whether or not the determination block 401 is the information embedding area 304 (S204).

  Here, the information embedding area determination process (S204) for determining whether or not the information embedding area 304 according to the first embodiment is described with reference to FIG. FIG. 11 is an explanatory diagram illustrating an outline of an image feature distribution used as a determination criterion in the information embedding region determination process according to the first embodiment.

  As shown in FIG. 11, the image feature distribution according to the first embodiment has xy coordinates in which a discontinuity scale is assigned as the vertical axis (y axis) and a density scale is assigned as the horizontal axis (x axis). It is composed of

  Furthermore, the image feature distribution shown in FIG. 11 includes, for example, an image feature distribution 901 indicating that the information embedding area 304 and the like are distributed, and a margin area that is a margin portion of the original image, for example, or only normal characters. An image feature distribution 902 indicating that an area other than the information embedding area such as a character printing area on which is printed is distributed.

  As a tendency of the image feature distribution 901, a discontinuous dot pattern or background pattern is displayed, or the dot pattern or the like and a character are superimposed to form a complicated shape. When the ratio (density scale) of the black image is the same as that of the feature distribution 902), the value of the discontinuity scale tends to increase.

  That is, at least when the above-mentioned density scale is the same, the discontinuity scale has a tendency of “margin area <character area <area where only information is embedded <area where information is embedded and character area”. “Information embedding area + character area” indicates an area in which information is embedded and a character is printed. For example, information by a digital watermark or the like is embedded, and a normal character is displayed on the area. This is the printed area.

  Therefore, in order to efficiently determine whether or not it is the information embedding area 304 according to the present embodiment, from the viewpoint of the discontinuity measure, the character area and the area where only information is embedded are used as boundaries. What is necessary is just to judge.

  By setting a boundary line 903 at the boundary between the character print area and the information embedding area, the discontinuity scale is equal to or greater than a predetermined threshold (first threshold), and the image density scale is a predetermined threshold (first threshold). 2 or more), it can be determined whether or not it is the information embedding area 304. Or you may determine whether it is the information embedding area | region 304 by the formula shown below.

  [Discontinuity scale]> [Concentration scale] × A + B (Expression 10)

  When the above expression 10 is satisfied, it is determined that the information embedded area 304 is present. However, A and B are predetermined threshold coefficients. That is, when the line segment “[discontinuity scale] = [density scale] × A + B” shown by the above equation 10 is above the boundary line 903 (third threshold value) shown in FIG. It is determined that

  From the above, the information area determination unit 104 can determine whether or not the image area of the determination block 401 is the information embedding area 304 by referring to the image feature distribution shown in FIG.

  The image feature distribution boundary line 903 according to the first embodiment shown in FIG. 11 has been described as an example of a single straight line, but is not limited to this example. For example, a plurality of straight lines The present invention can be implemented even when the boundary line 903 is formed from a combination of the above, or when the boundary line 903 is formed from a curve.

  When the determination process is completed, the remaining area of the document image that has not yet undergone the image feature calculation process (S203) is processed using the determination block 401, and the entire area of the document image is processed. When the determination process (S204) ends, the information detection process (S205) by the information detection unit 105 is performed only for the area determined to be the information embedding area 304 in S204.

  In the image feature calculation process (S203) according to the first embodiment, the case where the document image is a white or black binary image has been described as an example. However, the present invention is not limited to this example. For example, when the document image is a gray image or a color image, the image can be implemented without binarization. For example, in the case of the color image, 8 bits are allocated per pixel, and the image feature calculation process (S203) can be performed in the same manner as the binary image, with 8 bits as a unit.

  In the above case, the calculated discontinuity scale is the average value of the added values obtained by adding the absolute values of the differences between the target pixel in the determination block 401 and the preselected adjacent pixels, as in the case of the binary image. The density scale is a value obtained by subtracting the average luminance value from the maximum value that the luminance value in the determination block 401 can take. In the case of a color image, the image feature calculation process (S203) may be performed using only one color component, or the image feature calculation process (S203) may be performed for all color components.

  As described above, a series of operations of the information area determination process according to the first embodiment is completed. Even when the information embedding area 304 exists in a part of the document image, the information embedding area 304 is partially embedded. Since information can be detected only for the area 304, information detection processing can be performed quickly and efficiently.

  Also, the information embedding area determination apparatus 100 according to the first embodiment reads the original 101 and restores information from the information embedding area 304 regardless of the orientation of the original 101 even if the original 101 rotates. be able to. Even if a part of the document 101 is damaged, the information can be restored if the information embedding area 304 is not damaged. If position information indicating the location of the information embedding area 304 is embedded in the document in advance, if the position information is detected, only the information embedding area can be detected. In order to accurately read the embedded image, the position of the information embedding area 304 is detected when the direction of the document 101 is slightly different, or even if the image in which the position information is embedded is partially damaged. I can't.

  In the image feature calculation process (S203) according to the first embodiment, the discontinuity scale can be obtained by a simple XOR operation or a bit shift operation. The image feature calculation process (S203) can be performed at a very high speed.

  Further, when the information embedding area 304 is a partial area in the document image according to the first embodiment, information can be detected only for the information embedding area 304, so that it is necessary to execute the information detection process. Processing load or memory usage can be reduced, and processing time can be shortened.

  Next, a printed matter issuing apparatus provided with an information embedding area determination apparatus according to the second embodiment will be described with reference to FIG. FIG. 12 is a block diagram illustrating a schematic configuration of a printed matter issuing apparatus including the information embedding area determination apparatus according to the second embodiment.

  As shown in FIG. 12, a printed matter issuing apparatus 1100 according to the second embodiment includes, for example, a document reading unit (information reading unit) 1102, an information area temporary determination unit (area determination unit) 1104, and an information detection unit. (Information detection means) 1105, a copy permission / inhibition determination section (output control means) 1106, and a printing section (image output means) 1107 are provided.

  Note that the information embedding area determination apparatus according to the second embodiment is an apparatus including at least the information area temporary determination unit 1104 and the information detection unit 1105, but is not limited to this example. The area determination apparatus may further include a copy permission / inhibition determination unit 1106.

  The document reading unit 1102 reads the document 1101 and converts the image to generate a document image 1103. The configuration of the document reading unit 102 according to the first embodiment is almost the same as that of the first embodiment, and a detailed description thereof will be omitted.

  The document 1101 is substantially the same as the document 101 according to the first embodiment, and is a print document in which information is embedded with a digital watermark or the like, or a normal print document in which the information is not embedded.

  The information to be embedded includes copy prohibition information to prevent leakage of important documents. However, the information is not limited to this example. For example, information other than confidential information such as copy prohibition information can be implemented. Is possible.

  The printed matter issuing apparatus 1100 provided with the document reading unit 1102 to the printing unit 1107 has a function of not copying a document in which information including the copy prohibition information is embedded.

  The information provisional determination unit 1104 performs provisional determination processing as to whether or not any information such as copy prohibition information is embedded in the document image 1103.

  As a result of the provisional determination process, the information provisional determination unit 1104 transmits the document image to the information detection 1105 when it determines that the information such as the copy prohibition information is embedded in the document image. If it is determined as a result of the provisional determination processing that information such as copy prohibition information is not embedded in the document image, the document image 1103 is transmitted to the printing unit 1107 as it is and printed by the printing unit 1107.

  The information detection unit 1105 further executes detection processing for detecting an information embedding area 304 in which some information such as copy prohibition information is embedded in the document image.

  When the detected information is not copy prohibition information or the like, or when the detected information is copy enable information or the like, the information detection unit 1105 sends a document to the copy permission / inhibition determination unit 1106 together with print permission information for permitting printing. The image 1103 is transmitted.

  On the other hand, when the information detection unit 1105 detects information indicating that copying is prohibited, such as copy prohibition information, from the original image 1103, the information detection unit 1105 sends to the copy permission / inhibition determination unit 1106 together with print permission information indicating that printing is not permitted. An original image 1103 is transmitted. The information detection unit 1105 is not limited to such an example, and the information detection unit 1105 may not transmit the document image 1103 to the copy permission determination unit 1106 when printing is not permitted.

  The information detection unit 1105 according to the second embodiment is substantially the same as the information detection unit 105 according to the first embodiment, and thus detailed description thereof is omitted.

  The copy permission / non-permission determining unit 1106 refers to the print permission information or the print non-permission information transmitted from the information detection unit 1105, and determines whether the document image 1103 transmitted along with the print permission / non-permission is permitted.

  The original image 1103 transmitted to the copy permission / inhibition determination unit 1106 is transmitted to the printing unit 1107 and printed on a paper medium or the like by the printing unit 1107 only when printing is permitted by the copy permission / inhibition determination unit 1106.

  Note that the printed matter issuing apparatus 1100 according to the second embodiment includes, for example, a storage unit that stores various information, a control unit that controls processing of each unit, a display unit that displays a message or the like to the user on a screen, and the like. It has more.

  Note that the copy permission / inhibition determining unit 1106 according to the second embodiment performs a case where the document image 1103 is permitted to print / not permitted based on the print permission information or the print permission information transmitted from the information detection unit 1105. Although described with an example, it is not limited to such an example. For example, the copy permission / inhibition determination unit 1106 can be implemented even when determining whether printing is permitted or not based on whether or not the document image 1103 is transmitted from the information detection unit 1105 within a predetermined time limit.

  Next, an information embedding area temporary determination process according to the second embodiment will be described with reference to FIG. FIG. 13 is a flowchart illustrating an outline of a temporary determination process for an information embedding area according to the second embodiment.

  First, the original 1101 is read by the original reading unit 1102 and further image-converted to generate an original image 1103. When the original image 1103 is generated, the temporary information determination unit 1104 next divides the original image 1103 into a plurality of determination blocks 401 (S1201). Note that the determination block 401 is substantially the same as the determination block according to the first embodiment, and a detailed description thereof will be omitted.

  When the original image 1103 is divided into a plurality of determination blocks 401, the original image 1103 is composed of Nb determination blocks of determination blocks 401B (1) to 401B (Nb) as shown in FIG. The

  Next, the information area temporary determination unit 1104 executes a temporary determination process as to whether or not the information embedding area 304 is embedded with information such as copy prohibition information for each of the divided determination blocks 401 of the original image 1103 ( S1202).

  The provisional determination process for determining whether or not the information embedding area 304 of the determination block 401 according to the second embodiment is performed is performed based on whether or not the determination block 401 according to the first embodiment is the information embedding area 304. Since the determination process is substantially the same, detailed description thereof is omitted.

  When the temporary determination process (S1202) by the information area temporary determination unit 1104 is finished and it is determined that the area of the determination block 401 is the information embedding area 304, a memory such as a memory or a hard disk drive provided in the information embedding area determination device The determination counter stored in the unit (not shown) is incremented by one.

  In determining whether or not information such as copy prohibition information is embedded in the original image 1103, it is determined whether or not the determination counter is equal to or greater than a predetermined threshold T (fourth threshold) (S1203). Is done.

  If the determination counter is greater than or equal to the threshold T (S1203), it is determined that the information embedding area 304 is present in the document image 1103, and print permission information that prohibits printing of the document image 1103 is sent to the information detection unit 1105. It outputs (S1206).

  On the other hand, if the determination counter has not reached the threshold T (S1203), it is determined whether the determination block 401 is a terminal block of the determination block 401 into which the document image 1103 is divided (S1204). Note that the termination determination block 401 is, for example, the determination block 401B (Nb) shown in FIG.

  If it is not the end determination block 401B (Nb) (S1204), the temporary determination process target is moved to the next determination block 401, and the information embedding area 304 in which information such as copy prohibition information is embedded in the next determination block 401 Is temporarily determined (S1202).

  If it is the end determination block 401B (Nb) (S1205), the information area temporary determination unit 1104 determines that the information embedding area 304 does not exist in the document image 1103, and prints the document image 1103. Print permission information indicating permission is output to the information detection unit 1105 (S1205). Thus, a series of operations of the temporary determination process for the information embedding area according to the present embodiment is completed.

  From the above, the printed matter issuing apparatus having a function of not performing copying on a document in which copy prohibition information is embedded can quickly and accurately determine the presence or absence of an area in which copy prohibition information is embedded from the document image 1103. If copying is not prohibited, printing can be performed instantaneously without requiring further processing from the user, and a copy-prohibited document can be prevented from being erroneously printed.

  In the information embedding area provisional determination process according to the second embodiment, a case where the document image 1103 is divided into a plurality of determination blocks 401 in advance and then the information embedding area 304 is provisionally determined will be described as an example. However, the present invention is not limited to this example. For example, provisional determination processing (S1202) using the determination block 401 is executed from the upper left end of the original image 103, and then the determination block 401 is slid in the horizontal right direction or the vertical downward direction again. Even if the provisional determination process (S1202) is executed after the process has been performed, it can be implemented.

  Next, the series of processes described above can be performed by dedicated hardware or software. When a series of processing is performed by software, a program constituting the software is installed in a general-purpose computer or a microcomputer.

  The program can be recorded in advance on a hard disk, ROM, RAM, or the like as a recording medium built in the computer.

  Alternatively, the program is not limited to a hard disk drive, but is a removable recording medium such as a flexible disk, a CD-ROM (Compact Disc Read Only Memory), a MO (Magneto Optical) disk, a DVD (Digital Versatile Disc), a magnetic disk, and a semiconductor memory. Can be stored (recorded) temporarily or permanently. Such a removable recording medium can be provided as so-called package software.

  Further, in this specification, the processing steps for describing a program for causing the information embedding area determination device or the printed matter issuing device to perform various processes need not necessarily be processed in time series in the order described in the flowchart. It also includes processing executed in parallel or individually (for example, parallel processing or object processing).

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, this invention is not limited to this example. It is obvious for a person skilled in the art that various changes or modifications can be envisaged within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  In the above embodiment, the information area determination unit 104 or the information detection unit 105 included in the information embedding area determination device 100 is described as an example of hardware, but the present invention is not limited to such an example. For example, the information area determination unit 104 or the information detection unit 105 may be a program composed of one or two or more modules or components.

  In the above-described embodiment, the information area temporary determination unit 1104, the information detection unit 1105, or the copy permission / non-permission determination unit 1106 provided in the printed matter issuing apparatus 1100 has been described as an example. Is not limited to such an example. For example, at least one part among the above-described units may be a program composed of one or two or more modules or components.

  The present invention can be applied to an information embedding area determination device that determines whether or not an information is an embedded area and a printed matter issuing apparatus that can process a printed matter in which information is embedded.

It is a block diagram which shows the schematic structure of the information embedding area | region determination apparatus concerning 1st Embodiment. FIG. 4 is an explanatory diagram in which a part of a region where a dot pattern is embedded in a document is enlarged. It is explanatory drawing which shows an example of a dot pattern. It is explanatory drawing which shows the outline of the original image concerning 1st Embodiment. It is a flowchart which shows the outline of the determination process of the information embedding area | region concerning 1st Embodiment. It is explanatory drawing which shows the outline of the determination block concerning 1st Embodiment. It is explanatory drawing which shows the modification of the determination block shown in FIG. It is explanatory drawing which shows schematic structure of the attention pixel concerning 1st Embodiment. It is explanatory drawing shown about the outline of the calculation process of the discontinuity number concerning 1st Embodiment. It is explanatory drawing which shows the schematic structure of the original image concerning 1st Embodiment. It is explanatory drawing which shows the outline of the image feature distribution used as a determination reference | standard in the case of the information embedding area | region determination process concerning 1st Embodiment. It is a block diagram which shows the schematic structure of the printed matter issuing apparatus provided with the information embedding area | region determination apparatus concerning 2nd Embodiment. It is a flowchart which shows the outline of the temporary determination process of the information embedding area concerning 2nd Embodiment. It is explanatory drawing which shows the outline of the determination block concerning 2nd Embodiment.

Explanation of symbols

100 Information Embedded Area Determination Device 101 Document 102 Document Reading Unit 102
DESCRIPTION OF SYMBOLS 103 Original image 104 Information area | region determination part 105 Information detection part 1100 Printed matter issuing apparatus 1101 Original 1102 Original reading part 1103 Original image 1104 Information area temporary determination part 1105 Information detection part 1106 Copyability determination part 1107 Printing part

Claims (14)

An area determination that determines whether or not the image area of the document image generated by image conversion of the document is an area in which information cannot be viewed and is embedded with a discontinuous dot pattern With means,
The region determination means has an absolute value of a difference between a pixel value of one or more target pixels in the document image and a pixel value of a pixel in the vicinity of the target pixel being equal to or greater than a first threshold, and If the value calculated from the average of the pixel values of the pixels is greater than or equal to the second threshold, or (1) the absolute value of the difference between the pixel value of one or more pixels of interest and the pixel values near the pixel of interest; (2) A value calculated from an average of the pixel values of each pixel of interest, and the dot pattern is embedded when the result of linear combination of (1) and (2) is equal to or greater than a third threshold value An information embedding area determination device, characterized in that it is determined as an area. An area determination that determines whether or not the image area of the document image generated by image conversion of the document is an area in which information cannot be viewed and is embedded with a discontinuous dot pattern With means,
The region determination means divides the image region of the document image into a plurality of determination blocks, and among the pixels included in the determination block, the pixel value of one or more target pixels and the pixels near the target pixel. An average value of absolute values obtained by subtracting the pixel value is equal to or greater than a first threshold, and a value calculated from the average of the pixel values of the target pixel is a second value indicating the density of the image in the determination block. Or (1) the absolute value of the difference between the pixel value of one or two or more pixels of interest and the pixel value in the vicinity of the pixel of interest; and (2) the average of the pixel values of the respective pixels of interest. An information embedding area, wherein if the result of linear combination of (1) and (2) is greater than or equal to a third threshold value, it is determined that the dot pattern is an embedded area Judgment device. The area determination means detects an existing position of an area where the dot pattern is embedded in an image area of the document image by determining whether the area is an area where the dot pattern is embedded. The information embedding area determination device according to claim 1. The area determination means determines, for each determination block, whether the image area of the determination block is an area in which the dot pattern is embedded, so that the dot pattern in the document image is embedded. 3. The information embedding area determination device according to claim 2, wherein an existence position of the area is detected. The area determination means obtains an absolute value of a difference between a pixel value of the target pixel and a pixel value of a pixel near the target pixel by at least an XOR operation, a bit shift operation, or an AND operation. Item 5. The information embedding area determination device according to any one of Items 1, 2, 3, or 4. 5. The information embedding area determination device according to claim 1, wherein the area in which the dot pattern is embedded is a visible figure. 6. The pixel according to claim 1, wherein the pixel in the vicinity of the target pixel is at least one pixel among eight adjacent pixels adjacent to the target pixel. The information embedding area determination device according to the item. The region determination means calculates an absolute value obtained by subtracting a pixel value of the target pixel and a pixel value of a pixel adjacent to the left of the target pixel, and calculates a pixel value of the target pixel and a pixel value of the upper adjacent pixel of the target pixel. The information embedding area determination apparatus according to claim 7, wherein an average value of the added absolute values is obtained by adding to the absolute value obtained by subtracting. Image input means for reading a document and converting it into an image;
Image output means for printing or electronically outputting the document image after the image conversion;
An area determination means for determining presence / absence of an area in which a dot pattern having discontinuity is embedded in an image area of the document image in which information can be visually confirmed;
An information detecting unit that detects information by reading the region in which the dot pattern is embedded when the region determining unit determines that the region in which the dot pattern is embedded exists;
Output control means for stopping image output by the image output means when the information detected by the information detection means is document copy prohibition information indicating prohibition of copying of the document;
The region determination means divides the image region of the document image into a plurality of determination blocks, and among the pixels included in the determination block, the pixel value of one or more target pixels and the pixels near the target pixel. An absolute value obtained by subtracting the pixel value is added, an average value of the added absolute values is equal to or greater than a first threshold, and a value calculated from an average of the pixel values of the target pixel is equal to or greater than a second threshold Or (1) an absolute value of a difference between a pixel value of one or more target pixels and a pixel value in the vicinity of the target pixel; and (2) a value calculated from an average of the pixel values of each target pixel. When the result of linear combination of (1) and (2) is equal to or greater than a third threshold, it is determined that the document image includes an area in which the dot pattern is embedded. , Print issue device. Image input means for reading a document and converting it into an image;
Image output means for printing or electronically outputting the document image after the image conversion;
An area determination means for determining presence / absence of an area in which a dot pattern having discontinuity is embedded in an image area of the document image in which information can be visually confirmed;
An information detecting unit that detects information by reading the region in which the dot pattern is embedded when the region determining unit determines that the region in which the dot pattern is embedded exists;
Output control means for stopping image output by the image output means when the information detected by the information detection means is document copy prohibition information indicating copy prohibition of the document;
The region determination means divides the image region of the document image into a plurality of determination blocks, and among the pixels included in the determination block, the pixel value of one or more target pixels and the pixels near the target pixel. An absolute value obtained by subtracting the pixel value is added, an average value of the added absolute values is equal to or greater than a first threshold, and a value calculated from an average of the pixel values of the target pixel is equal to or greater than a second threshold Or (1) an absolute value of a difference between a pixel value of one or more target pixels and a pixel value in the vicinity of the target pixel; and (2) a value calculated from an average of the pixel values of each target pixel. If the result of the linear combination of (1) and (2) is greater than or equal to the third threshold, it is determined that the image area of the determination block is an area in which the dot pattern is embedded, and the dot In the area where the pattern is embedded When the number of the decision blocks judged as that is not less than the fourth threshold value, the character image, and judging an area in which the dot pattern is embedded is present, the printed matter issuing device. The printed matter issuing apparatus according to claim 9 or 10, wherein the region in which the dot pattern is embedded is a visible figure. The region determination means is characterized in that an absolute value of a difference between a pixel value of the target pixel and a pixel value of a pixel near the target pixel is obtained by at least an XOR operation, a bit shift operation, or an AND operation, The printed matter issuing apparatus according to any one of claims 9, 10, and 11. 13. The pixel according to claim 9, wherein the pixel in the vicinity of the target pixel is at least one of eight adjacent pixels adjacent to the target pixel. The printed matter issuing device described. The area determination means calculates an absolute value obtained by subtracting a pixel value of the target pixel and a pixel value of a pixel adjacent to the left of the target pixel, and calculates a pixel value of the target pixel and a pixel value of the adjacent pixel above the target pixel. The printed matter issuing apparatus according to claim 13, wherein an average value of the added absolute values is obtained by adding to the absolute value obtained by subtracting.

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