JP2012009926A - Tint image processing apparatus and tint image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To combine a tint image in such a manner that a code such as a QR code or a one-dimensional barcode does not become conspicuous.SOLUTION: An image forming apparatus 1 includes: an information embedding pattern detection section 206 for detecting an information embedding pattern image 5J indicating a code such as a QR code out of an inputted document image 50; a density change section 207 for changing a density of the information embedding pattern image 5J into a predetermined density to produce a density changed embedded image 5N; and an image combination section 209 for superimposing a tint pattern 5G comprised of a plurality of first isolate points of which the size can not be read by a scanner onto the document image 50 and replacing the information embedding pattern image 5J with the density changed embedded image 5N to produce a tint image 51 for output.

Description

  The present invention relates to an apparatus and method for synthesizing a tint block image with an input image.

  Conventionally, a code such as a QR (Quick Response) code or a one-dimensional barcode is sometimes printed on a printed material in order to restrict copying of the printed material or to manage copyright.

  However, when such a code is printed, the appearance of the printed matter may be deteriorated. Also, you may not want users to know much about the existence of code. Therefore, it is required to print the code so as not to stand out.

  By the way, a method using a copy-forgery-inhibited pattern image has been proposed as a method for printing information inconspicuously.

  As shown in FIG. 3, the “background pattern image” is composed of a large number of residual dots 6J and erase dots 6S. The residual dot 6J represents information by a character string or the like, and the erasing dot 6S camouflages the character string.

  Both the residual dot 6J and the erasure dot 6S are fine dots, but the residual dot 6J is a size that can be read by a scanner, and the erasure dot 6S is an impossible size. Therefore, when the material is copied from the original paper by the copying machine, only the residual dots 6J among the residual dots 6J and the erasure dots 6S are printed on the printed matter.

  In addition, the following method is proposed in the cited document 1. In synthesizing and outputting the divided character data and the modification data, the CPU determines whether or not the character data or the modification data exists. Note that the copy-forgery-inhibited pattern image data is used as the modification data. When both the character data to be output and the modification data exist, it is further determined whether or not the modification data exceeds a predetermined density. If the decoration data exceeds a predetermined density, the data is combined and output after bordering with one dot adjacent to the character dots of the character data turned off.

  According to this method, it is possible to make the characters easy to see even if the characters are synthesized on a base having a high density.

Japanese Patent Laid-Open No. 8-180047

  According to the method described in Patent Document 1, the presence or absence of the density of a part of pixels of a code such as a QR code or a one-dimensional barcode is reversed.

  However, even if such a code is read from the printed matter, the computer cannot analyze the code. It is conceivable to avoid a tint block image so as not to overlap the code and its surroundings. However, this makes the code stand out for the entire document.

  In view of such problems, an object of the present invention is to synthesize a tint block image so that a code such as a QR code or a one-dimensional barcode is not conspicuous.

  A tint block image processing apparatus according to an aspect of the present invention includes: a code image detecting unit that detects a code image that is an image indicating a code from input images; and a density of the detected code image is set to a predetermined density. A density change image generation unit that generates a density change image that has been changed to an image, and a ground pattern background image that includes a plurality of first isolated points having a size that cannot be read by the image reading unit that reads the image; Output image generating means for generating an output image for output by replacing the code image with the density-changed image.

  Preferably, the predetermined density is a density of the tint block background image.

  Alternatively, the changed image generation means may include a plurality of second isolated points having a size that can be read by the image reading means and a plurality of second isolated points arranged around the second isolated points as the density changed image. An image composed of the first isolated point is generated.

  Alternatively, the changed image generating unit generates an image including a plurality of lines that can be read by the image reading unit and a plurality of the first isolated points arranged around the lines as the density changed image. .

  Alternatively, the modified image generation means generates an image composed of the code image with reduced density and the plurality of first isolated points arranged around the code image as the density-changed image.

  A copy-forgery-inhibited pattern image processing apparatus according to another embodiment of the present invention includes a copy-forgery-inhibited pattern image including a plurality of first isolated points having a size that cannot be read and a readable image that can be read, and the copy-forgery-inhibited pattern image A reading unit that reads a surrounding image on which a plurality of second isolated points having a size that can be read are overlapped from a sheet, and a density-changed image in which the density of the read-out read image is changed is generated. Density change image generation means for performing output, and output image generation means for generating an output image for output including the read surrounding image and the generated density change image.

  Alternatively, the readable image is composed of a plurality of second isolated points having a size that can be read, and the density-change image generating means performs a closing process on the readable image, and the readable image that has been subjected to the closing process. Change the concentration of.

  Alternatively, the readable image is composed of a plurality of lines that can be read, and the density-change image generating means performs a closing process on the readable image and changes the density of the readable image that has been subjected to the closing process.

  Alternatively, the readable image is composed of a continuous pixel group having a predetermined density or more representing a code, and the density change image generating unit converts the readable image into a binary image, and the density of the binary image is changed. To change.

  According to the first to fifth and tenth aspects of the present invention, a tint block image can be synthesized so that a code such as a QR code or a one-dimensional barcode is not conspicuous. According to the inventions according to claims 6 to 9 and 11, the code image is preferably detected from the density-change image included in the output image obtained by the inventions according to claims 1 to 5 and 10, and the density is changed again. Can be output.

1 is a diagram illustrating an example of a configuration of an entire print system including an image forming apparatus. 2 is a diagram illustrating an example of a hardware configuration of an image forming apparatus. FIG. It is a figure which shows the example of a tint block image. It is a figure which shows the example of a manuscript image. It is a figure which shows the example of a structure of a tint block image generation part. It is a figure which shows the example of an information embedding pattern image and a density change embedding image. It is a figure which shows the example of a structure of the reading image process part. It is a figure which shows the example of a structure of the reading image process part. It is a figure which shows the example of a structure of the reading image process part. It is a figure which shows the example of the image of the code | cord | chord obtained by the copy-forgery-inhibited pattern image generation part.

  FIG. 1 is a diagram illustrating an example of the configuration of the entire printing system including the image forming apparatus 1. FIG. 2 is a diagram illustrating an example of a hardware configuration of the image forming apparatus 1. FIG. 3 is a diagram illustrating an example of a tint block image.

  An image forming apparatus 1 shown in FIG. 1 is an apparatus generally called a multi-function peripheral or MFP (Multi Function Peripherals), and is an apparatus in which functions such as copying, network printing (PC printing), fax, and scanner are integrated. .

  The image forming apparatus 1 can exchange image data with an apparatus such as a personal computer 4 via a communication line NW such as a LAN (Local Area Network), a public line, or the Internet.

  As shown in FIG. 2, the image forming apparatus 1 includes a CPU (Central Processing Unit) 10a, a RAM (Random Access Memory) 10b, a ROM (Read Only Memory) 10c, a mass storage device 10d, a scanner 10e, a printing device 10f, The network interface 10g, the touch panel 10h, the modem 10i, the copy-forgery-inhibited pattern image generation unit 10j, the read image processing unit 10k, and a control circuit are included.

  The network interface 10g is a NIC (Network Interface Card) for communicating with other devices such as a personal computer via the communication line NW.

  The touch panel 10h displays a screen for giving a message or an instruction to the user, a screen for the user to input processing commands and conditions, a screen showing the processing result of the CPU 10a, and the like. Moreover, the position which the user touched with the finger | toe is detected, and the signal which shows a detection result is transmitted to CPU10a.

  The scanner 10e is an apparatus that generates image data by reading an image such as a photograph, a character, a picture, or a chart on a sheet.

  The modem 10i is a device for exchanging image data with other fax terminals using a protocol such as G3 via a fixed telephone network.

  The printing device 10f prints the image indicated by the image data received from the personal computer 4 or another fax machine in addition to the image read by the scanner 10e. Hereinafter, these images are referred to as “original image 50”.

  The copy-forgery-inhibited pattern image generation unit 10 j generates a copy-forgery-inhibited pattern image 51 by converting an image such as a QR code or characters included in the document image 50 into a copy-forgery-inhibited pattern image or adding a new copy-forgery-inhibited pattern image.

  As shown in FIG. 3, the “background pattern image” is generally composed of a large number of small dots, but there are two types of sizes. These dots are isolated without touching each other. That is, these dots are isolated points.

  The larger dot can be read by a scanner, and a character or the like is represented by a set of these dots. Hereinafter, the larger dot is referred to as “residual dot 6J”.

  On the other hand, the smaller dot cannot be read by the scanner. Therefore, even if scanning is performed on a sheet on which these dots are printed, it seems that these dots have disappeared because they are not read. Therefore, these dots are hereinafter referred to as “erasing dots 6S”. The erase dot 6S is used for camouflaging the character string represented by the residual dot 6J.

  Returning to FIG. 2, the read image processing unit 10 k extracts a QR code or character that is camouflaged from the tint block image 51 read by the scanner 10 e and changes the density of the extracted QR code or character. Do.

  FIG. 4 is a diagram illustrating an example of the document image 50. FIG. 5 is a diagram illustrating an example of the configuration of the background pattern entering image generation unit 10j. FIG. 6 is a diagram illustrating an example of the information embedding pattern image 5J and the density-change embedding image 5N. FIG. 7 is a diagram illustrating an example of the configuration of the read image processing unit 10k.

  Next, the processing of the background pattern image generation unit 10j, the user's operation, and the like will be described by taking as an example the case where processing is performed on the document image 50 shown in FIG. As shown in FIG. 4, the document image 50 includes illustrations such as triangles or circles in addition to images such as characters, lines, and QR codes.

  As shown in FIG. 5, the background pattern image generation unit 10j includes an edge detection unit 201, a line width detection unit 202, a dot density detection unit 203, a fine line region determination unit 204, a dilation processing unit 205, and an information embedding pattern detection unit. 206, a density change unit 207, a tint block pattern generation unit 208, an image composition unit 209, and the like.

  The user prepares a document image 50 to be printed together with the copy-forgery-inhibited pattern image. For example, the document image 50 may be created using an application such as word processing software or drawing software of the personal computer 4. Alternatively, the original image 50 may be handwritten on a sheet. Hereinafter, a case where a document image 50 as shown in FIG. 4 is created using the drawing software of the personal computer 4 will be described as an example.

  When the user finishes creating the original image 50 with the drawing software, the user inputs a print command to the personal computer 4. At this time, an option for adding a tint block image is selected.

  Then, the personal computer 4 transmits a predetermined command in addition to the image data of the document image 50 to the image forming apparatus 1.

  When the image forming apparatus 1 receives image data and a predetermined command, the edge detection unit 201 or the tint block pattern generation unit 208 executes the following processing.

  The edge detection unit 201 performs edge detection processing on the document image 50. Thereby, an edge region which is an edge (contour) region of each character, line, QR code, and illustration included in 50 is detected.

  The line width detection unit 202 detects the width of a line included in the document image 50. In this embodiment, the line width is represented by the number of dots.

  The dot density detection unit 203 detects the number of dots having a predetermined density or more per unit area (hereinafter referred to as “dot density”) for each region in the document image 50 as follows.

  In the case of a QR code, the dot density detection unit 203 detects the dot density of the QR code by dividing the number of dots having a predetermined density or more constituting the QR code by the area of the smallest rectangle surrounding the QR code. . Similarly, in the case of a character, the dot density of the character is detected by dividing the number of dots having a predetermined density or more constituting the character by the area of the smallest rectangle surrounding the character. In the case of an illustration, the dot density of the illustration is detected by dividing the number of dots having a predetermined density or more constituting the illustration by the area of the illustration. Alternatively, when a plurality of lines are arranged, the dot density in the area surrounding these lines is detected by dividing the number of dots having a predetermined density or more constituting these lines by the area of this area.

The fine line area determination unit 204 extracts lines satisfying all of the following conditions (1) to (3) from among the lines included in the document image 50 as the “fine line area 5H”.
(1) The edge region extracted by the edge detection unit 201.
(2) A line whose width detected by the line width detection unit 202 is a predetermined value (for example, 3 dots) or less.
(3) The dot density detected by the dot density detector 203 is a predetermined value (for example, 0.5) or more.

  The dilation processing unit 205 performs dilation processing on the thin line region 5H determined by the thin line region determination unit 204 and expands the thin line region 5H, thereby detecting the thin line existence region 5Y. That is, when dilation processing is performed on each of the thin line regions 5H, a plurality of neighboring regions are bonded together to form one or a plurality of dot clusters. Each of these lumps is a thin line area 5Y.

  The background pattern generation unit 208 generates a background pattern having a density α. For example, when the density α is 10%, a tint block pattern in which black erasure dots 6S appear at a rate of one per 10 pixels is generated. Hereinafter, the pattern generated by the background pattern generation unit 208 is referred to as a “background pattern 5G”. Note that the concentration α can be arbitrarily set by the user.

  The information embedding pattern detection unit 206 extracts an image representing any information such as a QR code and a one-dimensional barcode from the document image 50, that is, an image in which some information is embedded. Hereinafter, such an image is referred to as an “information embedding pattern image”. As the information embedding pattern image, a code including a character string of a predetermined format such as “12345-00000” may be extracted. The information embedding pattern image detected by the information embedding pattern detection unit 206 is referred to as “information embedding pattern image 5J”.

  The density changing unit 207 corrects the information embedding pattern image 5J detected by the information embedding pattern detection unit 206 so that the density of the information embedding pattern becomes the density α.

  Examples of the correction method include the following three methods. Here, three methods will be described by taking as an example the case of correcting the character shown in FIG.

  The first method is a method of changing the density of the information embedding pattern image 5J to βmax × α as shown in FIG. “Βmax” is the maximum gradation value, and is “255” in the case of an 8-bit gradation, that is, an image having 256 gradations.

  In the second method, as shown in FIG. 6C, the information embedding pattern image 5J is represented by the residual dots 6J, but the surrounding density is set so that the overall density of the information embedding pattern image 5J becomes the density α. In this method, the dots are arranged at a distance greater than the pitch of the dots.

  The third method is a method of displaying the information embedding pattern image 5J on a screen of a predetermined pattern as shown in FIG. In this case as well, the lines in the screen are spaced so that the overall density of the information embedding pattern image 5J becomes the density α.

  Hereinafter, the information embedding pattern image 5J whose density has been corrected will be referred to as a “density changing embedded image 5N”.

  The image composition unit 209 arranges the density change embedded image 5N obtained by the density change unit 207 and the background pattern 5G obtained by the background pattern generation unit 208 on the original image 50 as follows, thereby inserting the background pattern. An image 51 is generated.

  The image composition unit 209 deletes the information embedding pattern image 5J from the document image 50, and at the position of the information embedding pattern image 5J, the density generated by the density changing unit 207 based on the information embedding pattern image 5J. A modified embedded image 5N is arranged. Further, the copy-forgery-inhibited pattern 5G is overlaid on the entire document image 50. However, the copy-forgery-inhibited pattern 5G is not superimposed on the thin line presence region 5Y. This is in order not to lose the clearness of the two adjacent fine lines. Further, the background pattern 5G is not superimposed on the density-change embedded image 5N. This is because the erased dot 6S has already been applied to the density-change embedded image 5N. By performing such processing on the document image 50, a tint block image 51 is generated.

  The tint block image 51 generated by the image composition unit 209 is printed on a sheet by the printing apparatus 10f.

  The user can copy the copy-forgery-inhibited pattern image 51 printed on the sheet onto another sheet by the image forming apparatus 1. At this time, the scanner 10e reads the tint block image 51 from the paper. Further, the read image processing unit 10k performs a process of changing the density of the density-change embedded image 5N in the background pattern image 51. Hereinafter, the read image processing unit 10k will be described in detail. Note that the read image processing unit 10k is particularly preferably used for the background pattern image 51 including the multi-value (non-binary multi-tone) information embedding pattern image as shown in FIG. 6B. It is done.

  The scanner 10e reads the copy-forgery-inhibited pattern image 51 by scanning a sheet. However, since the erase dot 6S is too small, it is easily affected by MTF deterioration. Therefore, the erase dot 6S is hardly read as a result. Therefore, the portion excluding the erased dot 6S in the background pattern image 51 is read. Hereinafter, an image read by the scanner 10e is referred to as a “read image 52”.

  As shown in FIG. 7, the read image processing unit 10k includes a background processing unit 301, a binarization processing unit 302, an information embedding pattern detection unit 303, a density change unit 304, an image composition unit 305, and the like.

  The background processing unit 301 performs background processing for removing noise in the read image 52 by adjusting the brightness of the read image 52. The background processing is particularly performed to remove isolated points such as residual dots 6J remaining in the read image 52. Hereinafter, the read image 52 subjected to the background processing is referred to as “read image 53”.

  The binarization processing unit 302 performs processing for converting the read image 53 into a binary image 54 that is a binary image.

  The information embedding pattern detection unit 303 detects an information embedding pattern image from the binary image 54. Hereinafter, the detected information embedding pattern image is described as “information embedding pattern image 5U”.

  The density changing unit 304 performs a process of changing the density of the information embedding pattern image 5U to the density β. In order to make it difficult for a human to recognize the information embedding pattern image 5U, the density β is set lower than the density α, and the density of the information embedding pattern image 5U is changed. Alternatively, when the density is indicated in the read image 52, the indicated density may be set as the density β.

  Hereinafter, the information embedding pattern image 5U whose density has been changed to the density β will be referred to as a “density changing embedded image 5M”.

  The image composition unit 305 deletes the information embedding pattern image 5U from the read image 53, and at the position of the information embedding pattern image 5U, the density change embedding obtained from the information embedding pattern image 5U by the density changing unit 304 is performed. The embedded image 5M is arranged. That is, the information embedding pattern image 5U is replaced with the density-change embedded image 5M. Hereinafter, the read image 53 subjected to the replacement is referred to as a “replacement image 55”.

  The replacement image 55 obtained by the image composition unit 305 is printed on a sheet by the printing apparatus 10f. Instead of printing, the image data of the replacement image 55 may be stored in a recording medium or transmitted to another device.

  FIG. 8 is a diagram illustrating an example of the configuration of the read image processing unit 10m. FIG. 9 is a diagram illustrating an example of the configuration of the read image processing unit 10n.

  Processing on the read image 52 may be performed by the read image processing unit 10m or the read image processing unit 10n instead of the read image processing unit 10k. The read image processing unit 10m is particularly preferably used for the background pattern-embedded image 51 including the information embedding pattern image as shown in FIG.

  As shown in FIG. 8, the read image processing unit 10 m includes a background processing unit 311, a residual dot detection unit 312, a closing processing unit 313, an information embedding pattern detection unit 314, a density change unit 315, and an image composition unit 316. Composed.

  The ground processing unit 311 performs ground processing to remove noise from the scanned image 52, as with the ground processing unit 301 of the scanned image processing unit 10k. Thereby, a read image 53 is obtained.

  The residual dot detection unit 312 detects the residual dot 6J from the read image 53. The residual dots 6J can be detected by a known method such as a so-called isolated point detection method.

  The closing processing unit 313 performs a closing process on the area of the read image 53 where the residual dot 6J is detected. That is, after the expansion process is performed a predetermined number of times, the contraction process is performed the same number of times. Thereby, the adjacent residual dots 6J are connected, and the information embedding pattern image is clearly restored. Hereinafter, the read image 53 that has been subjected to the closing process is referred to as a “closing processed image 5C”.

  The information embedding pattern detection unit 314 extracts an information embedding pattern image from the closing processed image 5C. Hereinafter, the extracted information embedding pattern image is referred to as “information embedding pattern image 5F”.

  Similar to the density changing unit 304 of the read image processing unit 10k, the density changing unit 315 performs processing for changing the density of the information embedding pattern image 5F to the density β. Hereinafter, the information embedding pattern image 5F in which the density is changed to the density β is referred to as a “density changing embedded image 5P”.

  Similar to the image composition unit 305 of the read image processing unit 10k, the image composition unit 316 erases the information embedding pattern image 5F from the read image 53, and the information embedding pattern image 5F is placed at the position of the information embedding pattern image 5F. A density-change embedded image 5P obtained from the image 5F by the density change unit 315 is arranged. That is, the information embedding pattern image 5F is replaced with the density-change embedded image 5P. Hereinafter, the read image 53 subjected to the replacement is referred to as a “replacement image 57”.

  Then, the replacement image 57 obtained by the image composition unit 316 is printed on a sheet by the printing apparatus 10f. As in the case of the replacement image 55, instead of printing, the image data of the replacement image 57 may be stored in a recording medium or transmitted to another device.

  As shown in FIG. 9, the read image processing unit 10n includes a background processing unit 321, a screen pattern detection unit 322, a closing processing unit 323, an information embedding pattern detection unit 324, a density change unit 325, an image composition unit 326, and the like. Composed. The read image processing unit 10n is particularly preferably used for the background pattern-embedded image 51 including the information embedding pattern image as shown in FIG.

  The ground processing unit 321 performs ground processing for removing noise of the scanned image 52, similarly to the ground processing unit 301 of the scanned image processing unit 10k and the ground processing unit 311 of the scanned image processing unit 10m. Thereby, a read image 53 is obtained.

  The screen pattern detection unit 322 detects a screen pattern 5S from the read image 53. For example, a line or dot pattern 5S arranged at equal intervals is detected. The pattern 5S can be detected by a known method.

  The closing processing unit 323 performs a closing process on the area of the read image 53 where the pattern 5S is detected. Thereby, adjacent lines or dots are connected, and the information embedding pattern image is clearly restored.

  Hereinafter, the information embedding pattern detecting unit 324, the density changing unit 325, and the image synthesizing unit 326 are the same processes as the information embedding pattern detecting unit 314, the density changing unit 315, and the image synthesizing unit 316 of the read image processing unit 10m. I do.

  That is, the information embedding pattern detection unit 324 extracts the information embedding pattern image 5F from the closing processed image 5D obtained by the closing processing unit 323. The density changing unit 325 generates the density-change embedded image 5P by changing the density of the information embedding pattern image 5F to the density β. Then, the image composition unit 326 generates a replacement image 57 by replacing the information embedding pattern image 5F in the read image 53 with the density-change embedded image 5P.

  According to the present embodiment, the copy-forgery-inhibited pattern image can be synthesized so that a code such as a QR code or a one-dimensional barcode is not conspicuous.

  FIG. 10 is a diagram illustrating an example of a code image obtained by the background pattern entering image generation unit 10j. For example, as shown in FIG. 10A, a large number of erase dots 6S are arranged in the background of the QR code, so that the occurrence of density unevenness can be suppressed. Further, since the erase dots 6S are arranged so that the density of the entire QR code is substantially the same as the density of the surrounding tint block image, the QR code can be made inconspicuous. Further, as shown in FIG. 10B, the QR code can be made less noticeable by reducing the concentration of the QR code.

  In the present embodiment, the read image 52 is acquired by the scanner 10e, but a digital camera or the like may be acquired.

  All or some of the functions of the read image processing unit 10k may be realized by software. In this case, a program describing the procedure of the above-described process may be prepared and executed by the CPU 10a. The same applies to the read image processing units 10m and 10n.

  In addition, the configuration of the entire image forming apparatus 1 or each unit, the processing content, the processing order, the data configuration, and the like can be appropriately changed in accordance with the spirit of the present invention.

1 Image forming device (background pattern image processing device)
10e Scanner (reading means)
206 Information embedding pattern detection unit (code image detection means)
207 Density changing unit (density changing image generating means)
209 Image composition unit (output image generation means)
304, 315, 325 Density changing unit (density changing image generating means)
305, 316, 326 Image composition unit (output image generation means)
51 Image with ground pattern (output image)
52 Scanned image 5J Information embedding pattern image (code image)
5N Density change embedded image (Density change image)
5P Density change embedded image (Density change image)

Claims (11)

Code image detection means for detecting a code image that is an image indicating a code from the input image;
A density change image generating means for generating a density change image in which the density of the detected code image is changed to a predetermined density;
By superimposing a ground pattern background image composed of a plurality of first isolated points having a size that cannot be read by an image reading means for reading an image on the input image, and replacing the code image with the density-changed image. Output image generation means for generating the output image of
A tint block image processing apparatus comprising: The predetermined density is a density of the background pattern background image.
The tint block image processing apparatus according to claim 1. The changed image generating means has a plurality of second isolated points having a size that can be read by the image reading means as the density changed image, and a plurality of the second isolated points arranged around the second isolated points. Generate an image consisting of a single isolated point,
The tint block image processing apparatus according to claim 1 or 2. The changed image generating unit generates an image including a plurality of lines that can be read by the image reading unit and a plurality of the first isolated points arranged around each line as the density changed image.
The tint block image processing apparatus according to claim 1 or 2. The changed image generating means generates, as the density changed image, an image composed of the code image having a reduced density and a plurality of the first isolated points arranged around the code image.
The tint block image processing apparatus according to claim 1 or 2. A copy-forgery-inhibited pattern image including a plurality of first isolated points having a size that cannot be read and a readable image that is a readable image, and a plurality of second patterns having a size that can be read around the copy-forgery-inhibited pattern image Reading means for reading a surrounding image on which isolated points are superimposed, from paper;
Density change image generation means for generating a density change image in which the density of the read readable image is changed;
Output image generation means for generating an output image for output including the read surrounding image and the generated density change image;
A tint block image processing apparatus comprising: The readable image comprises a plurality of second isolated points that are readable.
The density-changed image generating means performs a closing process on the readable image and changes the density of the readable image subjected to the closing process;
The tint block image processing apparatus according to claim 6. The readable image consists of a plurality of lines that can be read,
The density-changed image generating means performs a closing process on the readable image and changes the density of the readable image subjected to the closing process;
The tint block image processing apparatus according to claim 6. The readable image is composed of a continuous pixel group having a predetermined density or more representing a code,
The density-change image generating means converts the readable image into a binary image and changes the density of the binary image;
The tint block image processing apparatus according to claim 6. A code image that is an image indicating a code is detected from the input images that are input,
Generate a density-change image in which the density of the detected code image is changed to a predetermined density,
By superimposing a ground pattern background image composed of a plurality of first isolated points having a size that cannot be read by an image reading means for reading an image on the input image, and replacing the code image with the density-changed image. Generate an output image of
A tint block image processing method characterized by the above. A copy-forgery-inhibited pattern image including a plurality of first isolated points having a size that cannot be read and a readable image that is a readable image, and a plurality of second patterns having a size that can be read around the copy-forgery-inhibited pattern image Read the surrounding image with isolated points superimposed on the paper,
Generate a density-changed image in which the density of the read image that has been read is changed,
Generating an output image for output including the read surrounding image and the generated density change image;
A tint block image processing method characterized by the above.

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