JP5071315B2 - Background pattern image generation program and background pattern image generation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a program and a device for generating a background pattern for which a user can adopt an optional camouflage pattern. <P>SOLUTION: A background pattern image generation program generates image data of a background pattern composed of a latent image part and a background part whose output densities are different from each other when the background pattern is copied, and includes a camouflage pattern combining process (S46) in which first camouflage pattern data is inputted (S40) and combined camouflage pattern data is generated by combining the first camouflage pattern data and a second camouflage pattern having many shading change areas, and a background pattern image data generation process in which latent image part image data is generated based on a latent image part screen in an area corresponding to the latent image part and background part image data is generated based on a background part screen in an area corresponding to the background part with respect to a gray scale value of the combined camouflage pattern data. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a copy-forgery-inhibited pattern image generation program and a copy-forgery-inhibited pattern image generation device, and more particularly to a program and device for generating copy-forgery-inhibited pattern image data to be printed on a print medium. Furthermore, the present invention relates to a copy-forgery-inhibited pattern image data generation program and a copy-forgery-inhibited pattern image generation apparatus having an effect of suppressing copying of a print medium (original) on which a copy-forgery-inhibited pattern image is printed based on copy-forgery-inhibited pattern image data or an effect of distinguishing an original from a copy.

  The copy-forgery-inhibited pattern is combined with the original image of the original as a background, making it possible to distinguish whether the printed document is the original or a copy. Although it is difficult to identify the copy-forgery-inhibited pattern in the original, copying and copy-printing characters and images will emerge. By using this, it becomes possible to easily distinguish the original from the copy. In addition, since characters and images of the background pattern are revealed by copying, if the original is generated by synthesizing the background, an effect of psychologically suppressing the copy of the original can be obtained.

  The background pattern is described in Patent Document 1, and according to this description, it is as follows.

  The general structure of a tint block is composed of two areas: a “latent image portion” in which original dots remain or decrease little by copying, and a “background portion” in which original dots disappear or greatly decrease by copying. That is, the latent image portion has a small density change due to copying and the original image is reproduced as it is, and the background portion has a large density change due to copying and the original image disappears. A copy-forgery-inhibited pattern character or image is formed by these two areas, and the copy-forgery-inhibited pattern character or image is referred to as a “latent image”.

  The two areas of the latent image part and the background part have almost the same density. In the original state, it is difficult to distinguish the characters and images of the copy-forgery-inhibited pattern such as “copy” at a glance. Each have different characteristics. When copied, a difference in density between the latent image portion and the background portion is generated due to the difference in density change, so that it is easy to distinguish the characters and images of the tint block formed in these two areas.

  The latent image part is composed of a cluster of concentrated dots to make it easier to read dots during copying (scanning by copying), and the background part is made up of dispersed dots to make it difficult to read dots during copying. . By doing so, the latent image portion has a characteristic that dots are likely to remain after copying, and the background portion has a characteristic that the dots are more easily erased than the latent image portion. Concentrated dots and dispersed dots can be realized by halftone dot processing using halftone dots with different numbers of lines. That is, a halftone dot with a low line number is used to obtain a concentrated dot arrangement, and a halftone dot with a high line number is used to obtain a dispersed dot arrangement.

  In general, a copying machine has an image reproduction capability that depends on the input resolution in the process of reading minute dots of the original to be copied with a scanner and the output resolution in the process of reproducing minute dots read by the scanner with a print engine. There are limits. Therefore, if there are small dots in the document that exceed the limit of the image reproduction capability of the copier, the small dots cannot be reproduced completely in the copy, and the isolated small dots will disappear. . That is, if the background of the background pattern is created to exceed the limit of dots that can be reproduced by a copier, large dots (concentrated dots) on the background pattern can be reproduced by copying, but small dots (distributed dots) can be copied. Due to this, the latent image hidden in the copied manuscript appears. In addition, even if the dispersed dots in the background area do not disappear completely due to copying, if the degree of dot disappearance is large compared to the dots in the latent image area, a density difference will occur between the background area and the latent image area after copying. Then, a latent image hidden in the copied manuscript emerges.

  In the background pattern, a technique called “camouflage” is used to make it more difficult to distinguish characters and images hidden as latent images. This camouflage technology is a method of arranging a pattern with a density different from that of the latent image portion and the background portion over the entire tint block image. At first glance, a camouflage pattern with a different density from the latent image portion and the background portion is conspicuous. This has the effect of making the latent image less noticeable. That is, since the contrast of the camouflage pattern is large and the contrast between the latent image portion and the background portion is small, the latent image is more effectively hidden by the optical illusion. Furthermore, the camouflage pattern has an advantage that it can give a decorative impression to the printed matter and can create a background pattern with excellent design. In general, the camouflage pattern is created with two values indicating whether dots are generated or not, and the camouflage pattern is formed by not generating dots of the tint block in an area corresponding to the camouflage pattern. The binary camouflage pattern is described in Patent Document 2. The above is the outline of the background pattern.

  FIG. 1 is a diagram showing an example of a latent image of a tint block and a camouflage pattern. As shown in the enlarged view 10X, for example, the black portion corresponds to the latent image portion LI of the tint block and the white portion corresponds to the background portion BI of the tint block as shown in the enlarged view 10X. On the other hand, in the camouflage pattern 12, as shown in the enlarged view 12X, for example, a black portion CAM is a region where a background pattern dot is not formed, and a white portion is a region where a background pattern dot is formed.

  FIG. 2 is a diagram showing an example of the original copy-forgery-inhibited pattern. In the tint block 14, a latent image portion LI and a background portion BI are formed based on the latent image mask pattern 10 of FIG. The latent image portion LI is formed with dots with a low halftone line number (53 lpi) by the dot concentration type dither method, and the background portion BI is formed with dots with a high halftone line number (212 lpi) by the dot dispersion type dither method. . As is clear from the enlarged background pattern 14X, the entire background pattern has a constant output density, but the dots in the latent image portion LI are large dots because they are formed by a screen with a low number of dotted lines, and the background portion BI. These dots are minute dots because they are formed by a screen having a high number of dotted lines.

  The copy-forgery-inhibited pattern 16 is formed based on the latent image mask pattern 10 and the camouflage pattern 12 of FIG. 1 except that the latent image portion LI and the background portion BI are excluded from the black portion CAM region of the camouflage pattern. As shown in the enlarged tint block 16X, the entire tint block has a constant output density, and no dots are formed in the camouflage pattern area CAM. In other areas, a latent image composed of large dots is formed as in FIG. A portion LI and a background portion BI composed of minute dots are formed. Since the contrast of the camouflage pattern is large, the latent image (character “duplicate”) formed by the latent image portion LI and the background portion BI having a low contrast is inconspicuous.

  The original copy-forgery-inhibited pattern in FIG. 2 has the same output density of the latent image portion LI and the background portion BI, so that the latent image “double” formed thereby is concealed. This is called high concealment of the latent image in the original.

  FIG. 3 is a diagram showing an example of a copy of a background pattern. The copy 18 is formed through a scanning process and a dot formation process by copying, and as shown in the enlarged view 18X, the large dots in the latent image portion LI have hardly disappeared, but the small dots in the background portion BI. Has disappeared considerably. As a result, in the copy 18, the output density of the latent image portion LI hardly decreases, but the output density of the background portion BI decreases considerably, and the latent image “duplicate” appears to float. That is, the recognizability of the latent image in the copy is high.

  The copy 20 is the same as the copy 18 except for the camouflage pattern area CAM. The contrast of the camouflage pattern decreases due to the decrease in the output density of the background portion BI, and the latent image “double” appears to float.

4 is an enlarged view of the enlarged view of the original in FIG. 2 and the enlarged view of the copy in FIG. (A) In the original, the latent image portion LI is composed of dots (halftone dots) with a small number of halftone lines and a large area, and the background portion BI is composed of minute dots with a large number of halftone lines. No dot is formed in the black portion CAM of the camouflage pattern. On the other hand, in (b) the copied material, the size of the large dots (halftone dots) in the latent image portion LI has not changed so much, whereas a considerable number of small dots in the background portion BI have disappeared. . As a result, in the copied material, there is almost no decrease in the output density of the latent image portion LI, the output density of the background portion BI is greatly decreased, and the latent image “duplicate” of the tint block is manifested.
JP 2005-151456 A JP-A-4-170569

  As described above, the copy-forgery-inhibited pattern is required to satisfy both the high concealability of the latent image in the original and the high distinguishability of the latent image in the copy. Adding a camouflage pattern improves the concealment of the original, provides a decorative image to the printed matter, and provides a design with excellent design. Furthermore, by making it possible to use multi-level camouflage patterns exceeding 2 levels, the camouflage pattern can be used more freely, and a wide variety of images such as photographs, illustrations, CG, and logos can be used. The camouflage pattern can be used. For example, Japanese Patent Application No. 2008-7841 has filed a background pattern using a multi-tone camouflage pattern.

  However, if an arbitrary image by the user can be used as a camouflage pattern, an optimum copy-forgery-inhibited pattern image may not be obtained depending on the adopted image. For example, when the camouflage pattern has a small shade change region and the same density region is wide, the camouflage pattern is not conspicuous, and the concealability of the latent image in the original cannot be improved. This problem occurs similarly in the case where the adopted camouflage pattern has multiple gradations, and also in the case of two gradations.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a program and an apparatus for generating a tint block having an improved camouflage pattern while increasing the degree of freedom of the camouflage pattern.

In order to achieve the above object, according to the first aspect of the present invention, a tint block image generation step of generating tint block image data composed of a latent image portion and a background portion which are reproduced at the time of copying and having different output densities. In the copy-forgery-inhibited pattern image generation program for causing a computer to execute
A camouflage pattern synthesizing step of inputting first camouflage pattern data and synthesizing a second camouflage pattern having a larger shade change region with the first camouflage pattern data to generate synthesized camouflage pattern data;
Regarding the gradation value of the composite camouflage pattern data, latent image portion image data is generated based on the latent image portion screen in the region corresponding to the latent image portion, and based on the background portion screen in the region corresponding to the background portion. A tint block image data generating step for generating background image data.

  In the first aspect, according to a preferred embodiment, in the camouflage pattern synthesis step, the second camouflage pattern data adjusted by adjusting the gradation value of the second camouflage pattern data to a lower brightness. And adjusting the adjusted second camouflage pattern data with the first camouflage pattern data.

  In the first aspect, according to a preferred embodiment, in the adjustment step, a contrast enhancement process for enhancing the contrast of the gradation value is further performed on the gradation value of the second camouflage pattern data.

  In the first aspect, according to a preferred embodiment, in the adjustment step, the contrast of the gradation value of the edge portion of the second camouflage pattern is further enhanced with respect to the gradation value of the second camouflage pattern data. The sharpening process is performed.

  In the first aspect, according to a preferred embodiment, the method further includes an adjustment camouflage pattern registration step of storing the adjusted second camouflage pattern data in a memory after the adjustment step.

  In the first aspect, according to a preferred aspect, the method further includes an adjustment parameter registration step of storing an adjustment parameter used for adjustment in the adjustment step in a memory after the adjustment step.

  In the first aspect, according to a preferred embodiment, the camouflage pattern synthesizing step further includes an adjustment for generating synthesized camouflage pattern data adjusted by adjusting a gradation value of the synthesized camouflage pattern data to a lower brightness. And the tint block image data generation step uses the adjusted composite camouflage pattern data as the composite camouflage pattern data.

  In the first aspect, according to a preferred embodiment, in the camouflage pattern synthesis step, the density of the synthetic camouflage pattern is made lower than that of the first camouflage pattern, or the contrast of the synthetic camouflage pattern is set to the first camouflage pattern. A composite operation is performed that achieves at least one of higher than the pattern.

  In the first aspect, according to a preferred embodiment, the second camouflage pattern data is multi-tone image data exceeding two gradations.

  In the first aspect, according to a preferred embodiment, the camouflage pattern synthesizing step further generates modified second camouflage pattern data in which the second camouflage pattern is reduced and repeatedly arranged, and the modified second camouflage pattern data is generated. Are combined with the first camouflage pattern data.

  In order to achieve the above object, a second aspect of the present invention is the tint block image generation device according to the first aspect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

  FIG. 5 is a diagram showing a configuration of a printing system including the tint block image forming apparatus according to the present embodiment. The tint block image forming apparatus includes a printer driver program 32 installed in a host computer 30, a latent image portion dither matrix 33, a background portion dither matrix 34, camouflage pattern data 35, and a printer 40. The host computer 30 further includes a CPU, a RAM, and an application program 31, and executes the application program 31 to generate image data (print document image data) including characters, images, graphics, and the like.

  Further, in response to a request from the user, the host computer 30 executes the printer driver 32 to generate the camouflage-patterned tint block data 37. When a print request is received from the user for the image data generated by the application 31, the printer driver 32 generates print job data of the image data 36 based on a printer control language that can be interpreted by the printer device 40. If the print request includes adding copy-forgery-inhibited pattern data to the image data, the print job data includes the copy-forgery-inhibited pattern data 37 and transmits it to the interface IF of the printer 40.

  Then, the printer driver 32 combines the first camouflage pattern data input by the user with the second camouflage pattern data having a shade change area larger than that of the first camouflage pattern, and combines the combined camouflage pattern data with the tint block data. Then, camouflage pattern copy-forgery-inhibited pattern data 37 is generated.

  The image data 36 can take various forms, for example, data described in a page description language, data expanded in an intermediate code of a printer, or RGB bitmap data expanded in pixels. The camouflage pattern-attached copy-forgery-inhibited pattern data 37 is obtained by performing screening processing on tone data obtained by correcting (or modulating) the tone data of the two-tone or multi-tone camouflage pattern with the input tone of the copy-forgery-inhibited pattern. Image data. Further, the camouflage pattern-attached copy-forgery-inhibited pattern data 37 is image data of any color selected from among a plurality of color materials of the printer 40. When the color material of the printer 40 is CMYK four colors, for example, any of the CMK Such color image data is preferable. In the present embodiment, the camouflage pattern gradation data is 1-bit binary data in the case of 2 gradations, and binary data of 2 bits or more in the case of multiple gradations (3 gradations or more).

  On the other hand, the printer 40 includes a print engine 46 that generates an image, and a controller 41 that performs predetermined image processing on the received image data 36 and copy-forgery-inhibited pattern data 37 and further controls the print engine 42. The CPU of the controller 41 executes the image forming program 42 and generates bitmap data expanded into pixels from the received image data 36. If the received image data 36 is in the form of bitmap data, the bitmap data can be used as it is.

  When the image data 36 is composed of RGB gradation value data, the color conversion unit 43 performs color conversion to CMYK gradation value data. Then, the combining unit 44 selects bitmap data of the color (any one of CMK) selected as the background pattern color from the CMYK bitmap data of the color-converted image data 36, the dot data of the background pattern data 37, and Is synthesized. For example, the presence or absence of dots in the background pattern is converted into the maximum density value and the minimum density value of the bitmap gradation values, respectively, and synthesized. This composition is performed by, for example, a process of superimposing the image data 36 on the copy-forgery-inhibited pattern data 37. Further, the binarization unit 45 converts the CMYK gradation value data of the image data after the copy-forgery-inhibited pattern data is synthesized into dot data in the pixel and outputs it to the print engine 46. As a result, the print engine 46 generates an image in which the image to be printed generated by the application program and the copy-forgery-inhibited pattern image generated by the printer driver 32 are combined. This is the original copy of the background pattern.

In the embodiment of FIG. 5, the printer driver 32 of the host computer 30 generates the tint block data 37. However, as a modified example, the printer driver 32 generates print job data for designating generation of a tint block and a camouflage pattern in order for the controller 41 to generate a tint block and a camouflage pattern, and the controller 41 of the printer 40 uses the print job data. The ground pattern data with the camouflage pattern may be generated using the latent image portion dither matrix and the background portion dither matrix. The print job data for generating a tint block is data that contains information necessary to generate tint block data with a camouflage pattern, such as designation of characters or patterns that are lost or reproduced during copying, density of tint block, designation of camouflage patterns, etc. It is.
[Overview of tint block generation procedure]
Hereinafter, an outline of the tint block generation method by the tint block image generation device according to the present embodiment will be described. The copy-forgery-inhibited pattern image generating device refers to the host computer when a copy-forgery-inhibited pattern image is generated by the printer driver 32, and the printer 40 when the copy-forgery-inhibited pattern image is generated by the image forming program. In the present embodiment, in response to the first camouflage pattern arbitrarily selected by the user, the tint block image generation device performs high concealment of the latent image on the original, excellent design, and latent image on the copy. A second camouflage pattern having a larger shade change region is combined with the first camouflage pattern so as to satisfy high discriminability, and a tint block image data with a combined camouflage pattern is generated.

  FIG. 6 is a flowchart showing the procedure for generating the tint block data in the present embodiment. First, the tint block image generation device generates latent image mask pattern data (S1). The latent image mask pattern data is data of the latent image mask pattern 10 of the character “double” shown in FIG. 1, and is composed of data 0 and 1 indicating whether each pixel is the latent image portion LI or the background portion BI. The copy-forgery-inhibited pattern image generation apparatus inputs and acquires first camouflage pattern data having two gradations or colors or multiple gradations (S2). Arbitrary photograph data, image data, logo data and other color image data acquired by the user, and data selected from a plurality of camouflage pattern data 35 stored in the memory in the host computer 30 are the first camouflage. It becomes pattern data.

  The tint block image generation device sets the color of the camouflage pattern in response to the selection input of the tint block color from the user (S3). The color of the tint block is selected from any one of CMKs (cyan C, magenta M, black K) excluding Y having high brightness among the color materials CMYK of the printer. When the color camouflage pattern data is selected, the copy-forgery-inhibited pattern image generation device further calculates gray gradation value data from gradation value data of a plurality of colors (for example, RGB) included in the color camouflage pattern data, Monochrome multi-gradation camouflage pattern data is generated (S4). Then, the tint block image generation apparatus stores color camouflage pattern data or multi-grayscale camouflage pattern data composed of gray tone values in a memory in response to a registration command input from the user, and registers the first camouflage pattern. Perform (S5).

  If the tint change area of the first camouflage pattern data is smaller than the reference value, the copy-forgery-inhibited pattern image generation apparatus selects, by default, the second camouflage pattern data such as texture pattern data having a larger shading change area or a user. And synthesized with the first camouflage pattern data to generate synthesized camouflage pattern data (S6). As a result of making it possible to use the first camouflage pattern uniquely acquired by the user, there is a possibility that a pattern with poor shading change may be selected. However, when the first camouflage pattern has little change in shading, high concealment of the latent image in the original cannot be achieved. Therefore, the tint block image generation device generates synthesized camouflage pattern data by synthesizing texture data (second camouflage pattern data) having a larger shade change area with the first camouflage pattern data selected by the user. As a result, the latent image can be effectively concealed in the original by the synthetic camouflage pattern having many shade change regions.

  The multi-grayscale camouflage pattern data is composed of, for example, 8-bit grayscale data for each pixel, and the camouflage pattern can express 256 gray levels exceeding two gray levels. By adopting a multi-tone camouflage pattern, it is possible to suppress a decrease in the identification of the original printed document image in the original, and it is also possible to suppress a decrease in the identification of the latent image in the copy. Furthermore, since a multi-tone synthetic camouflage pattern can be used, a printed matter with excellent design can be created.

  In addition, even with two-level camouflage pattern data, by combining multi-tone texture pattern data (second camouflage pattern data), the combined camouflage pattern data becomes multi-tone, so the same as above The effect of this can be achieved.

The combined multi-grayscale camouflage pattern data is 8-bit (0: black to 255: white) tone value data for each pixel, and is gray image data expressed in 256 tones. The camouflage pattern is configured such that the output density is lower as the gradation value is closer to 0 (black), and the output density is higher as the gradation value is closer to 255 (white). Then, the output density DA of the background pattern output for the gradation value A (A = 0 to 255) of the camouflage pattern is as follows with respect to the output density Dmax of the background pattern when no camouflage pattern is added.
DA = (A / 255) × Dmax (0 ≦ A ≦ 255) (1)
become.

  Therefore, when the gradation values of the camouflage pattern are all white (A = 255), the output density DA of the background pattern with the camouflage pattern is DA = Dmax, which is the same output density as the background pattern without the addition of the camouflage pattern. In other words, the output is in an area other than the 16 pattern CAM in FIG. Further, the closer the gradation value of the camouflage pattern is to 255 (white), the smaller the amount of decrease in the background pattern output density Dmax. On the other hand, the closer the gradation value of the camouflage pattern is to 0 (black), the larger the reduction amount of the output density Dmax of the tint block. When the gradation values of the camouflage pattern are all black (A = 0), the output density DA of the background pattern with the camouflage pattern is DA = 0, and the background pattern dots are not formed. That is, the output is in the 16 pattern CAM in FIG.

  As described above, a multi-level synthetic camouflage pattern is synthesized with the latent image portion and background portion of the background pattern, and the contrast of the camouflage pattern is lowered as compared with binary camouflage pattern data consisting of 1 bit. be able to.

  In order to reflect the above-described composite camouflage pattern on the background pattern, the background pattern image generation device generates corrected composite camouflage pattern gradation data based on the input gradation of the latent image portion and the background portion (S7). The input gradation of the latent image portion and the background portion corresponds to the output density of the tint block image, and the gradation value determined by default or the scale corresponding to the output density of the tint block image arbitrarily selected by the user. It is a key value. As shown in the above formula (1), the background pattern image with a composite camouflage pattern is an image obtained by modulating the background pattern image composed of the latent image portion and the background portion with the gradation value of the multi-level composite camouflage pattern. In other words, it is an image in which the gradation value of the multi-tone synthetic camouflage pattern is modulated by the input gradation of the tint block image.

  Finally, the copy-forgery-inhibited pattern image generation device performs screening processing on the corrected composite camouflage pattern gradation data with reference to the latent image portion dither matrix 33 or the background portion dither matrix 34 in accordance with the latent image mask pattern data, and the camouflage pattern The counterfeit suppression tint block data 37 is generated (S8). That is, in the area corresponding to the latent image portion, the background pattern image data is generated by referring to the latent image portion dither matrix 33, and in the area corresponding to the background portion, the background pattern image data is referred to by the background portion dither matrix 34. Is generated.

  The latent image portion and background portion dither matrices 33 and 34 are, for example, a threshold matrix, a gradation conversion matrix, and the like, both of which are dither matrices that can be converted into multi-gradation image data. The dither matrices 33 and 34 may be AM screens that express multiple gradations by dot area, or FM screens that express multiple gradations by dot density. However, as the original function of the tint block image, the output density reproduced at the time of copying needs to be different between the latent image portion and the background portion. Therefore, a screen capable of realizing this is required. For example, the latent image portion and background portion dither matrices 33 and 34 have different numbers of screen lines. Or a dot concentration type matrix and a dot dispersion type matrix.

Hereinafter, a procedure for generating the background pattern data with a camouflage pattern in the present embodiment will be described in detail.
[Latent image part dither matrix and background part dither matrix]
The latent image portion is formed into an image having a predetermined output density by a plurality of first dots (dots having a large area) using the latent image portion dither matrix 33, while the background portion uses the background portion dither matrix 34. Thus, an image having a predetermined output density is formed by a plurality of second dots (small area dots). In order to increase the concealment capability of the latent image in the original, it is desirable that the latent image portion and the background portion have an image with the same output density.

  FIG. 7 is a diagram illustrating an example of input / output characteristics of a dither matrix for generating images of the background portion BI of the background pattern and the latent image portion LI. The input / output characteristics of the background portion dither matrix 34 and the input / output characteristics of the latent image portion dither matrix are the same as shown in FIG. These dither matrices 34 and 33 have a characteristic that the output density is 0 to 12% with respect to the input gradation (0 to 255). In the above-described screening process S8 in FIG. 6, the corrected combined camouflage pattern gradation data becomes the input gradation, and the output gradation data for obtaining the above output density characteristics is generated with reference to these dither matrices 34 and 33. The When the corrected composite camouflage pattern gradation data is In = 255, the output density of the corrected composite camouflage pattern is 12% of solid black. Then, the output density of the corrected composite camouflage pattern varies within a range of 0 to 12% according to the gradation value of the composite camouflage pattern.

  FIG. 8 is a diagram showing the background portion dither matrix 34. The background portion dither matrix 34 is composed of a relatively large small dot D2-1 consisting of 5 pixels and a relatively small small dot D2-2 consisting of 1 pixel, and dot dispersion in which each other is stably dispersed and arranged. Type dither matrix. The relatively large small dot D2-1 is assigned to the pixel at the position of the displacement vector (−6, 6) (6, 6), and the number of screen lines is 71 lpi. The small dots D2-2 are positioned at a stable interval between the small dots D2-1. By making it possible to generate relatively large small dots D2-1 in the small dots, it is possible to stably generate small dots in the background portion. However, since the small dots D2-1 and D2-2 each have a smaller area than the large dot D1 in the latent image portion described later, the extent of disappearance during copying is larger than the large dot D1 in the latent image portion.

  In FIG. 8, thresholds 1 to 254 are assigned to elements displayed in black or gray where small dots are formed, and thresholds 255 are assigned to other elements. In the screening process S8, for input gradations 0 to 254, dots are formed in the pixels corresponding to the lower threshold elements, but when the input gradation is 255, the threshold 255 elements are used. Corresponding pixels are controlled to be dot-off, and dots are formed in pixels corresponding to elements having a threshold value of 254 or less. Therefore, when the input gradation is 254 or 255, dots are formed in the pixels corresponding to all the black or gray elements in FIG. 8, and the output density is 12%.

  FIG. 9 is a diagram showing the latent image portion dither matrix 33. The latent image portion dither matrix 33 is a dot concentration type dither matrix having a low screen line number (53 lpi) for generating a large dot D1. As shown in FIG. 7, the output density characteristic of the latent image portion dither matrix 33 with respect to the input tone value In is also 0% to 12% of the black level with respect to the input tone value In = 0 to 255. It has become. This characteristic is the same as that of the background portion dither matrix 34 in FIG. Furthermore, the size of the large dot D1 generated by the latent image portion dither matrix 33 is 22 dots at maximum. Since the large dot D1 in the latent image portion is larger than the small dots D2-1 and D2-2 in the background portion in FIG. 8, compared to the background portion, the disappearance of dots during copy-forgery-inhibited pattern images is small and the density change is small.

In FIG. 9, thresholds 1 to 254 are assigned to the elements where the large dots D1 are formed, and thresholds 255 are assigned to the other elements. Then, in the screening process S8, as in the background portion, dots are formed in pixels corresponding to threshold elements lower than that for the input gradations 1 to 254. When the input gradation is 255, the threshold value 255 is used. The pixel corresponding to the element is controlled to be dot-off, and a dot is formed in the pixel corresponding to the element having a threshold value of 254 or less. Therefore, when the input gradation is 254 or 255, dots are formed in the pixels corresponding to all the elements of black or gray in FIG. 9, and the output density is 12%.
[Generation method of copy-forgery-inhibited pattern image data]
Hereinafter, a method for generating copy-forgery-inhibited pattern image data with a multi-tone camouflage pattern according to the present embodiment will be described.

  FIG. 10 is a flowchart showing a method for generating copy-forgery-inhibited pattern image data in the present embodiment. The printer user selects a tint block generation menu in the printer driver 32 of the host computer 30 and executes generation of tint block image data according to the flowchart of FIG.

  When the user generates a latent image mask pattern independently, first, the user inputs a word of a background pattern (S10). For example, words such as “copy”, “copy”, and “confidential” are used, and this word becomes a latent image of a background pattern. Further, the size of the tint block word such as 48 points is input (S11), the angle of the tint block word such as 40 degrees is input (S12), and the tint block effect and arrangement are selected (S13). The copy-forgery-inhibited pattern effect is one in which the wording is white (the wording is white and the surrounding is black) or the wording is black (the wording is black and the surrounding is white). In the case of white, the wording becomes the latent image portion around the background portion, and in the case of the relief, the wording becomes the latent image portion and the surrounding portion becomes the background portion. In addition, the arrangement of the tint block includes a square arrangement, a diagonal arrangement, a reverse arrangement, and the like.

  FIG. 11 is a diagram illustrating an example of the tint block effect. The copy-forgery-inhibited pattern patterns 50 and 51 are examples of the copy-forgery-inhibited pattern effect in which the wording is “copy” and “copy” and the wording appears. The copy-forgery-inhibited pattern patterns 52 and 53 are examples of the copy-forgery-inhibited pattern effect in which the words are outlined with the same wording. In both cases, the wording angle is set to 40 degrees.

  FIG. 12 is a diagram illustrating an example of the arrangement of a background pattern. In all cases, the wording is “copy”, the angle is 40 degrees, and the tint block effect is revealed. (A) In the square arrangement, the latent image mask pattern is attached in a tile shape. (B) In the oblique arrangement, the latent image mask pattern is arranged so as to be shifted by a predetermined phase for each line feed. (C) In the reverse arrangement, the latent image mask pattern is arranged upside down at each line feed.

  When the input or selection by the user is completed in steps S10 to S13, the printer driver 32 generates a latent image mask pattern (S14). As shown in FIG. 14, the example of the latent image mask pattern is composed of 1-bit data capable of distinguishing the latent image area from the background area.

  When the user uses the default latent image mask pattern, S10 to S14 are omitted, and the latent image mask pattern is selected by the user.

  Next, the printer driver 32 sets the input gradation value of the tint block image (S16). When the background portion dither matrix 34 and the latent image portion dither matrix 33 shown in FIGS. 7 and 8 are used, it is desirable to set the input gradation value of the tint block image to the maximum value “255”. By setting the input gradation In = 255, when the corrected composite camouflage pattern gradation data has the maximum gradation value 255, the output density of the latent image portion and the background portion of the tint block image is 12% of the black solid color, which is the maximum concentration. This is because the higher the output density of the copy-forgery-inhibited pattern image, the higher the discrimination of the copy-forgery-inhibited pattern image in the copy. However, the input gradation value may be selected to be lower than 255 depending on the user's preference.

  The printer driver 32 acquires camouflage pattern data of two gradations or color or multi-gradation according to the user's selection request (S17). Camouflage pattern data arbitrarily acquired by the user is stored in a memory in the host computer or in an external memory, and the camouflage pattern data is acquired in response to a user's selection request. The selected camouflage pattern data is stored in the memory and registered.

  FIG. 13 is a diagram illustrating an example of a camouflage pattern and an example of a tint block image employing the camouflage pattern. The camouflage pattern 54 is composed of a combination of a plurality of rectangular areas, and the gradation value A of each rectangular area is as shown in FIG. A copy-forgery-inhibited pattern image 55 when such a multi-tone camouflage pattern is selected is shown. In this tint block image 55, the output density Dmax (for example, Dmax = 40%) of the tint block image is multiplied by A / 255 by the above-described equation (1). In this way, in the region where the camouflage pattern is darker (region where A is close to 0), the output density of the tint block image is lower, and in the region where the camouflage pattern is whiter (region where A is close to 255), the output of the tint block image There is less decrease in concentration.

  The gradation value A of the camouflage pattern is gray data as described above. When the camouflage pattern is RGB color image data, the gray gradation value A is obtained by the following equation (2).

A = 0.3 × R + 0.59 × G + 0.11B (2)
As a result of defining the gray gradation value of the camouflage pattern data as “0” for black and “255” for white, the camouflage pattern image based on the camouflage pattern data and the camouflage pattern image reflected in the background pattern are reversed in black and white Become an image. Therefore, in order for the user to be able to select a camouflage pattern in a state where it is reflected in the background pattern, it is desirable that the printer driver 32 displays a camouflage pattern image in which black and white are reversed on the selection screen. The gradation value K of the image data of the black-and-white inverted image is obtained by the following equation (3).

K = 255-A (3)
Further, the printer driver 32 selects a tint block color (black, cyan, magenta, etc.) in response to a user's selection request (S18). The tint block color should be a single color. Accordingly, the gradation value of the camouflage pattern data of any one of the CMKs is set to the gradation value K of Expression (3) obtained by inverting the gradation value A of the gray data as described above. The reason for this is due to the difference between RGB of additive color display and CMYK of subtractive color display. Comparison with the threshold value of the threshold value dither matrix of the latent image portion and background portion described later is performed for the gradation value K or the gradation value of the correction camouflage pattern gradation.

  Next, the printer driver 32 generates a composite camouflage pattern (S19). In the present embodiment, it is possible to use an arbitrary two-gradation or color or multi-gradation camouflage pattern acquired by a user by taking a picture. For this reason, there is a pattern having an image quality that is not suitable for being combined with a tint block image in which the shade change region of the first camouflage pattern is too small. Therefore, it is necessary to synthesize the second camouflage pattern having a greater change in the shadedness with the first camouflage pattern. Either the camouflage pattern data after adjustment or the parameters necessary for adjustment is stored in the memory. The adjustment process will be described in detail later.

  When S10 to S19 such as the above input by the user are completed, the printer driver 32 executes a tint block image generation process (S20). The tint block image generation processing is performed according to the flowchart of FIG.

  FIG. 14 is a flowchart of the tint block image generation process in the present embodiment. That is, the flowchart of FIG. 14 corresponds to the tint block image generation process S20 of FIG. First, the corrected composite camouflage pattern data is generated by correcting (or modulating) the gradation value of the composite camouflage pattern data based on the input gradation values of the latent image portion and the background portion (S21). This procedure corresponds to procedure S7 in FIG.

  The gray level A (0 ≦ A ≦ 255) of the composite camouflage pattern, and the input gray level value In (0 ≦ In ≦ 255) of the latent image portion and the background portion constituting the background pattern are assumed. In this step S21, first, the gray gradation value A of the composite camouflage pattern is converted into a gradation value K (= 255-A) of subtractive color mixture. The gradation value Ki of the corrected composite camouflage pattern is calculated by the following equation (4).

Ki = (K / 255) × In (4)
This arithmetic expression corresponds to the above-described expression (1).

  In step S16 of setting the input gradation value of the tint block image in FIG. 10, if the input gradation values of the latent image portion and the background portion are set to the maximum value (for example, 255) that can be taken, the corrected composite camouflage pattern The gradation value Ki is Ki = K. If the input gradation value is set to a value smaller than 255, the gradation value Ki of the corrected composite camouflage pattern correspondingly becomes a low gradation value (low density, bright) according to the equation (4). In any case, the output gradation value obtained by referring to the dither matrices 33 and 34 based on the gradation value Ki is a value that reproduces an output density of 0 to 12%.

  Returning to FIG. 14, for the corrected composite camouflage pattern gradation data, the copy-forgery-inhibited pattern image data with the camouflage pattern is generated by referring to the latent image portion dither matrix 33 or the background portion dither matrix 34 according to the latent image mask pattern (S23). To S32). The camouflage pattern-attached copy-forgery-inhibited pattern image data is image data indicating the presence or absence of dots for each pixel.

  FIG. 15 is a diagram for explaining the tint block image generation processing of FIG. FIG. 15A shows a tint block image in which a plurality of latent image mask patterns 10 are squarely arranged in a print size 60 of A4. In the case of the A4 size, the number of pixels is 4720 dots in the horizontal direction and 6776 dots in the vertical direction. FIG. 15B shows the positional relationship between the latent image mask pattern 10 in the upper left of FIG. 15A and the camouflage pattern 12 arranged in a tile shape. The latent image mask pattern 10 is a square pattern having 2030 dots in the horizontal direction and 2030 dots in the vertical direction. On the other hand, as shown in FIG. 15C, the camouflage pattern 12 is a square pattern having 215 dots in the horizontal direction and 215 dots in the vertical direction.

  FIG. 15D is an enlarged view of the upper left end region of FIG. As will be described later, a texture pattern having a size of 43 × 43 is synthesized with the first camouflage pattern 12. Compared to the shade change region (for example, the edge region) of the first camouflage pattern 12, the shade change region of the texture pattern 14 that is the second camouflage pattern is larger. Further, as shown in FIG. 15D, the latent image portion dither matrix 33 and the background portion dither matrix 34 are both 32 × 32 matrices and correspond to pixels so that they are pasted in a tile shape in order from the upper left. Let

  Then, the printer driver compares the gradation value Ki of the corrected composite camouflage pattern with the threshold value of the dither matrix 33, 34, and if the gradation value Ki is equal to or greater than the threshold value according to the logic described in FIGS. If the pixel dot is ON and the gradation value Ki is less than the threshold value, the pixel dot is turned OFF. The dither matrix to be compared is selected corresponding to black or white of the latent image mask pattern.

  Returning to the flowchart of FIG. 14, the tint block image generation processing will be described. The pixel indexes i and j are initialized to i = 0 and j = 0, respectively (S23). If the latent image mask pattern is black at pixel (i, j) (YES in S28), the threshold value of the corresponding pixel in the latent image portion dither matrix 33 is compared with the corrected composite camouflage pattern gradation value Ki (S29). If the latent image portion mask pattern is not black (NO in S28), the threshold value of the corresponding pixel in the normalized background portion dither matrix 34N is compared with the gradation value Ki (S31). In any comparison, when the gradation value Ki is equal to or greater than the threshold value, the output image (i, j) is dot ON (S30), and when the gradation value Ki is less than the threshold value, the output image (i, j) is dot OFF. (S32). However, as described with reference to FIGS. 7 and 8, no dot is formed in the element of the threshold value 255.

  As a result, first dots (halftone dots) having a size corresponding to the corrected composite camouflage pattern gradation value Ki are generated in the latent image portion, and the number of second dots corresponding to the gradation value Ki is associated in the background portion. It is generated in the pixel at the position.

  When the above processing is completed, the pixel row index j is incremented (j = j + 1) (S24), and the same processing is repeated until the index j reaches the print size width (S25). When the index j reaches the print size width (YES in S25), the index i in the column direction is incremented (i = i + 1) and the index j in the row direction is reset to 0 (S26), and the same processing is repeated. When the index i in the column direction reaches the print size height (YES in S27), the copy-forgery-inhibited pattern image generation processing for one page is completed. In this way, the processing target pixel moves from the upper left in the raster scan direction, and each pixel is turned ON or OFF.

Through the above processing, copy-forgery-inhibited pattern image data reflecting a multi-tone camouflage pattern is generated.
[Concrete example]
The generation of a copy-forgery-inhibited pattern image with a multi-tone synthetic camouflage pattern in the present embodiment will be described with a specific example.

  FIG. 16 is a diagram illustrating an example of a latent image mask pattern. A latent image mask pattern 10 is formed in a 32 × 32 matrix. The pattern 10A corresponds to the latent image portion, and the pattern other than the pattern 10A corresponds to the background portion. Therefore, the matrix data of the latent image mask pattern has 1 bit of “0” (latent image portion) or “1” (background portion) in each pixel of the 32 × 32 matrix.

  FIG. 17 is a diagram illustrating an example of a camouflage pattern. In the camouflage pattern 12, the pixels in the 32 × 32 matrix have nine stripe-shaped regions 12A to 12I. The gradation values K of the regions 12A to 12I are as illustrated. That is, the areas 12A, 12E, and 12I are white areas having a gradation value “255”, and the areas 12B and 12H are areas that are closest to black with the gradation value “64”. The camouflage pattern is a multi-tone synthetic camouflage pattern, but the first camouflage pattern and the second camouflage pattern (texture pattern) are not shown in order to simplify the explanation.

  FIG. 18 is a diagram illustrating an example of the corrected composite camouflage pattern gradation value. The corrected composite camouflage pattern gradation value data 120 is obtained by the above-described equation (4). In this example, the tone value data is obtained by correcting the composite camouflage pattern tone value of FIG. 17 based on the input tone value In = 255 of the tint block image. In FIG. 18, the latent image mask pattern 10A is shown in gray, and the camouflage pattern areas 12A to 12I are shown divided by broken lines. The gradation value Ki of the corrected composite camouflage pattern is shown in FIG. 24 with respect to the gradation value K of the camouflage pattern shown in FIG. Since the input tone value In of the copy-forgery-inhibited pattern image is 255, the tone value Ki of the corrected composite camouflage pattern matches the composite camouflage pattern K.

  FIG. 19 is a diagram illustrating an example of a tint block image with a camouflage pattern. This is because the copy-forgery-inhibited pattern image obtained as a result of screen processing with reference to the latent image portion dither matrix 33 and the background portion dither matrix 34 in FIGS. 7 and 8 for the gradation value Ki of the corrected composite camouflage pattern shown in FIG. 16. In the figure, camouflage pattern areas 12A to 12I are indicated by alternate long and short dash lines, and the latent image mask pattern 10A is indicated by broken lines.

  In the latent image mask pattern 10A, in the region 12E, the first dot D1 for the correction gradation Ki = 255, and in the regions 12D, 12C, 12F, and 12G, the first dot D1 for the correction gradation Ki = 192, 128 is present. Is formed. Outside the latent image mask pattern 10A, in the region 12A, the second dot D2 for the correction gradation Ki = 170 is formed on all displacement vectors, and the other regions 12B, 12C, 12D, 12F, 12G, and 12H. However, the second dots D2 for the correction gradations Ki = 64, 128, 192, 192, 128, 64 are formed.

  As shown in the copy-forgery-inhibited pattern image, by employing a multi-tone synthetic camouflage pattern, dots having a density or size corresponding to the gradation value of the camouflage pattern are formed in the copy-forgery-inhibited pattern image.

FIG. 20 shows an example of a tint block image in the case of a two-tone camouflage pattern. In the two-tone camouflage pattern, only the areas 12A, 12E, and 12I with dots and the areas 12X and 12Y without dots exist. That is, there are no intermediate gradation regions 12B, 12C, 12D, 12F, 12G, and 12H. Therefore, no dots are formed in the regions 12X and 12Y.
[Optimization of any camouflage pattern]
In the present embodiment, a camouflage pattern of two gradations or color or multi-gradation arbitrarily acquired by a user through photography or computer graphics can be registered, and can be combined with a ground pattern. By installing such a camouflage pattern function in the printer, the degree of freedom of the camouflage pattern increases and the convenience of the user increases.

  However, as the degree of freedom of the camouflage pattern is increased, registration of a pattern that is not suitable for the copy-forgery-inhibited pattern image may be required, and a predetermined process is required in order to accept arbitrary camouflage pattern data. In the following, we will explain the possible problems when accepting an arbitrary camouflage pattern.

  FIG. 21 is a diagram showing an inappropriate copy-forgery-inhibited pattern image when an arbitrary camouflage pattern is adopted. It is assumed that a camouflage pattern 112 is adopted for the latent image mask pattern 110 composed of the characters “copy”. The camouflage pattern 112 is a multi-tone pattern in which the logo of the character “EPSON” is arranged in a dispersed manner, but has a wide area where there is no change in density between the characters “EPSON”. That is, the camouflage pattern 112 is a pattern having a small or narrow shade change region. For this reason, the original camouflage pattern-attached tint block image 116 does not make the camouflage pattern conspicuous and does not exhibit the effect of enhancing the concealment property of the latent image “copy”. However, the copy-forgery-inhibited pattern image 120 with the camouflage pattern is sufficiently distinguishable from the latent image “copy”.

  Therefore, in the present embodiment, when the shade change area of the first camouflage pattern selected by the user is small, the second camouflage pattern having a greater shade change area is combined with the first camouflage pattern. As the second camouflage pattern, for example, a texture pattern with multiple gradations exceeding two gradations is appropriate. Therefore, in the present embodiment, when a plurality of texture pattern data is stored in advance in the memory of the host computer and the first camouflage pattern has a small shade variation area, the printer driver 32 displays the texture pattern to the user. A texture pattern is selected or automatically selected and synthesized with the first camouflage pattern.

  The texture pattern which is the second camouflage pattern is multi-gradation pattern data, and as a result, the synthesized camouflage pattern has multiple gradations. Therefore, even if the first camouflage pattern is two-gradation image data, the synthesized camouflage pattern becomes multi-gradation image data, so that the original print image can be identified in the original copy-forgery-inhibited pattern image with the camouflage pattern. Deterioration can be suppressed.

  Second, in the present embodiment, the user may arbitrarily select the second camouflage pattern. In this case, in order to make the arbitrarily selected second camouflage pattern more appropriate, the printer driver 32 performs processing for reducing the brightness, processing for improving the contrast, and sharpness for improving the contrast of the edge portion. Adjustment processing such as conversion processing is performed. By adjusting the second camouflage pattern in this way, the composite camouflage pattern can be made a more appropriate pattern. The adjusted second camouflage pattern data and adjustment parameters can be stored in the memory.

  Third, when synthesizing the first and second camouflage patterns, the user can appropriately select from the synthesis methods registered in advance by the printer driver, and the camouflage patterns synthesized by the selected synthesis method can be selected. You can check it on the preview screen. When synthesizing a second camouflage pattern such as a multi-tone texture pattern with the first camouflage pattern, the first camouflage pattern is synthesized so as to cover the texture pattern in a tile shape. As a result, the shade change region of the synthetic camouflage pattern increases, and the latent image concealment property in the original can be improved.

  Fourth, in place of or in addition to the adjustment process for the second camouflage pattern described above, the second camouflage pattern is reduced, and the reduced second camouflage pattern is repeated in a tile shape so that there are more shade change regions. A texture pattern may be generated and used as the second camouflage pattern.

  FIG. 22 is a flowchart of the synthetic camouflage pattern generation step S19 in the tint block generation step of FIG. First, the printer driver inputs arbitrary first camouflage pattern data by the user in response to an instruction from the user (S40). For example, the data of the camouflage pattern 112 shown in FIG. Then, the printer driver determines whether or not the ratio of the shade change area of the input first camouflage pattern data is greater than the reference value (S41). For example, a histogram of the first camouflage pattern data is acquired, and it is determined whether or not the ratio of the shade change area is greater than the reference value based on the fact that many pixels are concentrated in a specific narrow density area. To do. When the ratio of the shade change area is large, the first camouflage pattern data is registered as it is. Alternatively, the first camouflage pattern data may be registered by performing adjustments such as a process for reducing the brightness of the first camouflage pattern data, a process for improving the contrast, and a sharpening process for improving the contrast of the edge portion.

  If the ratio of the shade change area of the user's first camouflage pattern data does not reach the reference value (YES in S41), the printer driver recommends that the user should synthesize the second camouflage pattern and the user (S42). When the user agrees to the recommendation (YES in S42), the printer driver automatically selects the second camouflage pattern data or selects the second camouflage pattern data selected in response to the selection instruction by the user. Input (S43).

  The second camouflage pattern data is selected from, for example, texture data registered in advance in the memory. The texture data registered in the memory in advance has a sufficient shade change area as a camouflage pattern. However, when the second camouflage pattern data is pattern data arbitrarily acquired by the user, there may be a case where there is not a sufficient shade change region. Therefore, when the pattern data arbitrarily acquired by the user as the second camouflage pattern data is selected, the printer driver acquires a histogram of the pattern data, and the ratio of the shade change area exceeds the reference value. It is determined whether or not (S44). If the reference value has not been reached (NO in S44), the second camouflage pattern data is adjusted (S45). A specific adjustment method will be described in detail later.

  In place of the second camouflage pattern adjustment process, the second camouflage pattern is reduced to increase the ratio of the shade change region, and the reduced second camouflage pattern is adjusted to be tiled repeatedly. The camouflage pattern may be generated.

  Finally, the printer driver synthesizes the second camouflage pattern data with the original camouflage pattern data (first camouflage pattern data) (S46). For example, the printer driver causes the printer driver to select from a plurality of synthesis methods registered in advance by the user, or a recommended synthesis method.

  FIG. 23 is a diagram illustrating an example of textures registered in advance in the second camouflage pattern. In the figure, (a) brick-like texture, (b) canvas-like texture, (c) gravel-like texture, (d) linen-like texture, and (e) tile-like texture are shown. Each of these texture patterns is a multi-tone pattern in which the tone value frequently changes within a narrow region, and is a pattern with many shade change regions. Any texture data is data for generating a relatively small texture image of 43 × 43 dots, for example.

  FIG. 24 is a diagram for explaining the tint block image generation processing. FIG. 24 is a diagram corresponding to FIG. 15, and FIGS. 24C and 24D show the relationship between the first camouflage pattern 12 and the texture pattern 13 which is the second camouflage pattern. In this example, the first camouflage pattern data 12 is relatively large pattern data of 215 × 215 dots, whereas the texture pattern 13 that is the second camouflage pattern is relatively small of 43 × 43 dots. Pattern data. Then, the texture pattern 13 is synthesized so as to be repeatedly arranged in a tile shape with respect to the first camouflage pattern 12.

  FIG. 25 is a diagram illustrating an example of a synthesized camouflage pattern. In the drawing, three synthesis methods, (a) multiplication, (b) overlay, and (c) synthesis camouflage pattern by hard light are shown. The arithmetic expressions corresponding to these three synthesis methods are as follows.

Here, Cam is the gradation value of the first camouflage pattern, Tex is the gradation value of the texture pattern, and Cam ′ indicates the gradation value after synthesis. These gradation values are all gray values, and 0 ≦ Cam ′, Cam, Tex ≦ 255. X and y are the x coordinate and y coordinate of each pattern.

  In the first synthesis method, (a) multiplication is performed by simply multiplying the gradation value Cam of the first camouflage pattern and the gradation value Tex of the texture pattern, as shown in the equation (5). It is a normalized one. As shown in FIG. 25A, the pattern synthesized by multiplication becomes dark overall.

  As shown in Expression (6), the overlay (b) of the second synthesis method is performed when the gradation value Cam of the first camouflage pattern is “128” or more (when bright), the gradation values Cam and Tex. When the gradation value Cam of the first camouflage pattern is less than “128” (when dark), the multiplication value of the gradation value Cam and Tex is obtained. Therefore, (b) in the pattern synthesized by overlay, the bright part of the first camouflage pattern is emphasized and the dark part becomes darker. As shown in FIG. 25 (b), the contrast of the first camouflage pattern is Go up and stand out.

  In the third synthesis method (c) hard light, as shown in Expression (7), when the texture pattern gradation value Tex is “128” or more (when bright), the gradation value Cam and Tex are added. The multiplication value is subtracted from the value, and when the gradation value Tex of the texture pattern is less than “128” (when dark), the multiplication value of the gradation value Cam and Tex is set. Therefore, (c) the pattern synthesized by the hard light emphasizes the bright part of the texture pattern and darkens the dark part, and the contrast of the texture pattern becomes more noticeable as shown in FIG. .

  FIG. 26 is a diagram showing an example of a user interface screen in the tint block generation process (FIG. 10) by the printer driver. This screen 250 includes a copy-forgery-inhibited pattern image preview area 251, a copy-forgery-inhibited pattern word setting area 252, its file setting area 253, an input tone value setting area 254, a copy-forgery-inhibited pattern color setting area 255, a camouflage pattern addition button 256 and an OK button 257. Have. When the camouflage pattern addition button 256 is clicked, a screen for setting the next camouflage pattern is displayed.

  FIG. 27 is a diagram showing an example of a user interface screen in the synthetic camouflage pattern generation step S19 by the printer driver. The screen 130 selects a region 132 for selecting a first camouflage pattern, a preview region 133 for the selected first camouflage pattern, a region 134 for selecting a texture pattern as a second camouflage pattern, and a synthesis method. An area 135, a composite camouflage pattern preview area 136, and a texture pattern adjustment button 137 are provided. The user can confirm the selected first camouflage pattern in the preview area 133, and can confirm the selected texture pattern and the synthesis method in the preview area 136. In the example of FIG. 27, the camouflage pattern of the logo “EPSON” is selected, the brick-like texture is selected as the texture pattern, and the overlay is selected as the synthesis method.

FIG. 28 is a diagram showing a tint block image formed using the camouflage pattern synthesized according to the example of FIG. The original copy-forgery-inhibited pattern image 216 is obtained by adding a synthesized camouflage pattern as a background pattern to the characters “copy” of the latent image. The composite camouflage pattern has an effect of concealing the pattern of the latent image “copy” by increasing the density change region by synthesizing the texture pattern (second camouflage pattern) with the first camouflage pattern. In addition, the composite camouflage pattern is a multi-tone pattern, and the contrast is lower than that of the two-tone pattern, and the distinguishability of the originally printed image is not impaired. In the synthetic camouflage pattern, since the low gradation area (dark area) has a lower gradation (darker), the copy of the copy-forgery-inhibited pattern image 220 contains more dots in the latent image portion of the latent image “copy”. The dots in the background area disappear, and the latent image of the copied material is improved. In FIG. 27, compared with FIG. 21, the concealment of the original is improved, and the identification of the copy remains high.
[Arbitrary texture pattern (second camouflage pattern)]
In this embodiment, in addition to selecting a texture pattern as the second camouflage pattern from a plurality of texture patterns registered in advance, an arbitrary pattern can be registered by the user. Thereby, the effect of the concealment property of the latent image in the original copy-forgery-inhibited pattern and the synthetic camouflage pattern can be enhanced. However, in accordance with the fact that an arbitrary texture pattern can be registered by the user, in this embodiment, the printer driver has a function of adjusting a texture pattern or a synthetic camouflage pattern.

  The texture pattern is a multi-tone image or a color image exceeding two gradations. In the case of a color image, the texture pattern arbitrarily acquired by the user is converted into an image having a gray value (luminance value) by the above-described equation (2). This gray image is set to the same background pattern image texture pattern as the background pattern color (one of CMK).

  It is desired that the camouflage pattern synthesized with the background pattern has a moderately low brightness (high density). The reason is that if the brightness of the composite camouflage pattern is high (the density is low), the brightness of the original tint block is also high (the density is low), the dot size in the latent image area is reduced, and the dot reproducibility during copying is reduced. This is because the lowering of the latent image makes it difficult to identify the latent image in the copy. Furthermore, if the brightness is simply lowered, the brightness difference of the composite camouflage pattern is reduced, the contrast is lowered, and the composite camouflage pattern becomes inconspicuous in the tint block image. If it becomes inconspicuous, the design of the original tint block will be impaired, and the latent image of the original tint block will not be improved. Therefore, it is necessary to increase the contrast of the synthetic camouflage pattern.

  In order to decrease the brightness of the composite camouflage pattern and increase the contrast, the brightness of the texture pattern is decreased and the contrast is increased, or the brightness of the composite camouflage pattern is decreased and the contrast is increased. Hereinafter, the adjustment processing for setting the decrease in brightness and contrast will be described using a texture pattern as an example.

  The printer driver has the adjustment function described above so that the multi-tone texture pattern of the gray image becomes an optimal composite camouflage pattern. This texture pattern adjustment function includes (1) a function for reducing the brightness when the brightness of the texture pattern is higher than a reference value, (2) a function for increasing the overall contrast of the texture pattern, and (3) an edge of the texture pattern. It has a function (or a sharpening function or an unsharp function) for increasing the contrast of the portion. These adjustment functions are selected by designating adjustment parameters by the user.

  FIG. 29 is a diagram for explaining the function of increasing the brightness and reducing the overall contrast. It is description of the function of said (1) and the function of (2). The first texture pattern adjustment method includes the lightness reduction process (1) and the overall contrast improvement process (2). That is, as adjustment of the texture pattern, contrast correction is performed by the following equation (9), and brightness reduction correction is further performed by equation (8).

FIG. 29A shows a lightness reduction correction table of Expression (8), and FIG. 29B shows a contrast correction table of Expression (9). In either case, the horizontal axis represents the input gray gradation value Gray (equivalent to the above-described gray gradation value A), and the vertical axis represents the converted output gray gradation value Gray. In the above equation (9), for the gray gradation value Gray, based on the contrast index fa defined by the contrast parameter C (0 ≦ C ≦ 50) and the inflection points x1 and x2, the high gray gradation value is Higher and lower gray tone values are corrected lower. The contrast parameter C = 50 is the strongest contrast correction. The larger the contrast parameter C, the stronger the contrast correction. In contrast parameter C = 0, the input and output have a linear relationship, and no contrast correction is performed. According to the equation (9), when the input gray gradation value Gray is 0 to x1, gradation value conversion is performed by a cubic curve, and when the gray gradation value Gray is x1 to x2, the gradation value is represented by a linear line of the gradient fa. Conversion is performed, and when the gray gradation value Gray is x2 to 255, gradation value conversion is performed using a cubic curve.

  The gradation value Gray_C adjusted for contrast according to Expression (9) is subjected to brightness reduction adjustment according to Expression (8), and the gradation value Gray_V subjected to contrast adjustment and brightness adjustment is obtained. When the lightness parameter V = 100, the lightness reduction is not corrected. The lightness parameter V is corrected to be lower as the lightness parameter V is smaller, and the lightness is corrected to 40% when the lightness parameter V = 40.

  FIG. 29C shows a composite gradation conversion table for simultaneously performing contrast correction and brightness reduction correction when the contrast parameter C and the brightness parameter V are set to certain values. In the figure, a conversion table when C = 10 and V = 80 and a conversion table when C = 30 and V = 55 are shown. Setting C = 0 enables no contrast correction, and setting V = 0 allows no brightness reduction correction.

  FIG. 30 is a diagram showing a texture pattern that has undergone overall contrast correction and brightness correction, a synthetic camouflage pattern, and a tint block image that uses the texture pattern. In this example, the adjusted texture pattern 330 is obtained by adjusting the gradation of the brick-like texture pattern data using the composite gradation conversion table of C = 30 and V = 55 in FIG. The texture pattern 330 is corrected to have a low brightness as a whole, and the overall contrast is enhanced. As a result, a composite camouflage pattern 332 is generated by combining the first camouflage pattern 112 of FIG. 21 and the adjusted texture pattern 330 by overlay. This synthetic camouflage pattern 332 also has low brightness and high contrast.

  The gray gradation value Gray_V of the composite camouflage pattern 332 is inverted to the gradation value K (= 255−Gray_V), and the gradation value K is corrected by the input gradation value In = 255 of the tint block image (Ki = (K / 255). ) × In), and the corrected tone value Ki is compared with the threshold values of the background portion and latent image portion dither matrices 34 and 33 shown in FIGS.

  The copy-forgery-inhibited pattern original 316 has an enhanced contrast of the composite camouflage pattern 332, so that it is discriminating even when it is dark as a whole, the concealability of the latent image in the copy-forgery-inhibited pattern original 316 is enhanced, and the design is excellent. Furthermore, since the brightness of the synthetic camouflage pattern 332 is corrected as a whole, large dots are formed in the latent image portion in the original copy-forgery-inhibited pattern. Therefore, the density change during copying differs greatly between the latent image portion and the background portion, and the identification of the latent image “copy” on the copy-forgery-inhibited pattern copy 320 is high.

  Next, in the second texture pattern adjustment method, the above (1) lightness reduction processing and (3) processing for increasing the contrast of the edge portion of the texture pattern (or sharpening function or unsharp function) are performed. .

  FIG. 31 is a diagram for explaining the function of increasing the contrast of the edge portion of the texture pattern. It is a figure explaining the function of said (3). In the first adjustment method, the correction of the contrast of the entire texture pattern is simple, but the number of gradations in the bright and dark areas decreases due to the uniform contrast correction, and conversely the contrast is impaired. Will occur. Therefore, in the second adjustment method, the camouflage pattern can be adjusted more appropriately by enhancing the contrast of the edge portion, which is a characteristic portion of the image, by the function (3).

  That is, the human eye has a characteristic that the sensitivity is high for the edge portion where the brightness of the image changes greatly, and the sensitivity is low for the portion where the change in brightness is flat. Therefore, if the contrast of the edge portion of the multi-tone texture pattern is emphasized, the contrast of the synthetic camouflage pattern of the copy-forgery-inhibited pattern original appears high to human eyes, and the concealment of the latent image in the original copy-forgery-inhibited pattern can be enhanced. Furthermore, emphasizing the edges of the texture pattern reproduces the features of the texture pattern more faithfully, leading to improved design.

  Specifically, for a pixel of interest with a gray texture pattern, the edge region is enhanced, that is, sharpened, by detecting how much the pixel of interest differs from the surrounding region and emphasizing the difference. . The sharpening calculation formula is as follows.

According to the equation (10), as shown in FIG. 31A, with respect to the gradation value Gray_V subjected to the brightness reduction correction, the gradation value of the target pixel Gray_V (i, j) and the surrounding 7 × 7 The difference from the average value of the gradation values of the pixels of the pixel is obtained, and is enhanced (multiplied) according to the enhancement parameter STRENGTH, and added to the original gradation value Gray_V (i, j). Moreover, said Formula (11) is a formula which calculates | requires an average value. As a result of these calculations, as shown in FIG. 31B, in the edge portion, low gradation value pixels on both sides of the edge are converted to lower gradation values, and high gradation value pixels are converted to higher gradation values. The contrast of edges is enhanced. In FIG. 31B, the horizontal axis represents the x and y directions of the image, and the vertical axis represents the brightness of the image.

  In the above arithmetic expression, by increasing the parameter AREA indicating the size of the surrounding area, the area around the edge can be blurred, and the sharpening can be realized naturally without increasing the enhancement parameter STRENGTH. Note that the number of screen lines used in forming a tint block image is relatively low, so the resolution is low, and even if the parameter AREA is increased to blur the area around the edge, the quality of the tint block image does not deteriorate.

  Note that the sharpening process is also referred to as an unsharp process. For example, “Ohanashi Color Image Processing”, CQ Publisher, Satoshi Hirohiro, details unsharp masking.

  FIG. 32 is a diagram showing a texture pattern, a synthetic camouflage pattern and a copy-forgery-inhibited pattern image using the texture enhancement, sharpening, and brightness correction of the edge portion. In this example, the brick-like texture pattern is subjected to lightness reduction processing using the composite gradation conversion table of V = 60 and C = 0 in FIG. 29, sharpened using Expression (10), and adjusted texture network. 430 is generated. Then, a composite camouflage pattern 432 synthesized with the camouflage pattern 112 of FIG. 21 is generated, and a copy-forgery-inhibited pattern image 416 with a camouflage pattern and a copy copy-forgery-inhibited pattern image 420 are generated. That is, the texture pattern data is converted to gray gradation value Gray, converted to gradation value by a combined gradation conversion table of C = 0 and V = 60 (Gray_V), and sharpened by AREA = 25 and STRENGTH = 2. An edge-contrast enhancement process is performed, and an adjusted texture pattern 430 is generated. The texture pattern 430 is corrected to have low brightness as a whole, and the contrast is enhanced only at the edge portion.

  The texture pattern 430 and the first camouflage pattern are combined by overlay, the gray gradation value Gray_V of the composite camouflage pattern 432 is inverted to the gradation value K (= 255−Gray_V), and the gradation value K is input to the tint block image. The tone value In = 255 is corrected (Ki = (Gray_V / 255) × In), and the corrected tone value Ki is compared with the threshold values of the background portion and latent image portion dither matrices 34 and 33 in FIGS. An original copy-forgery-inhibited pattern image 416 is generated.

  The original copy-forgery-inhibited pattern 416 in FIG. 32 is superior in design with no gradation collapse (decrease in the number of gradations) in the low gradation region and the high gradation region as compared with FIG. 30, and the edge portion of the texture pattern is emphasized. Therefore, the concealability of the latent image of the copy-forgery-inhibited pattern original 416 is improved. Further, since the brightness is lowered, the copy-forgery-inhibited pattern 420 has a higher latent image discrimination. Therefore, generally, FIG. 32 can provide a tint block image quality superior to that of FIG.

In addition to the above-described (1) lightness reduction correction, it is desirable to select either (2) correction for enhancing the overall contrast or (3) correction for enhancing the contrast of the edge portion. For example, when the multi-tone texture pattern and the first camouflage pattern are synthesized, if the contrast is too strong due to the sharpening process and the fidelity of the first camouflage pattern original is impaired, (2) the overall contrast It is better to adopt a correction. Conversely, when the fidelity of the first camouflage pattern original is not impaired, (3) sharpening processing is preferably employed.
[Process for adjusting texture pattern (second camouflage pattern)]
The adjustment of the texture pattern (second camouflage pattern) may be automatically performed when the user registers the texture pattern, or may be manually performed by the user. In either case, if the user can adjust the texture pattern not only when registering the texture pattern, but also at any time after registration, the tint block image quality can be adjusted according to the user's preference, and the convenience for the user is improved.

  FIG. 33 is a flowchart of the process for automatically adjusting the texture pattern (second camouflage pattern) of FIG. When registering the texture pattern, the printer driver executes the automatic adjustment process shown in FIG. First, in response to a user's specification, the printer driver inputs texture pattern data (second camouflage pattern data) (S50). The texture pattern data is either multi-gradation image data exceeding 2 gradations or color image data. If the texture pattern data is color data (S51), the printer driver converts the texture pattern data to gray data (S52) and stores it in the memory (S53).

  Then, the printer driver determines whether the stored gray data is bright or not, and determines whether the average gradation value of the gray data is high (for example, 25% or more of the maximum gradation value) (S54). If bright, V = 40 and C = 0 are set (S55), if low (if dark), V = 100 and C = 0 are set (S56), and gray data is converted to gradation values according to the composite conversion table. To do. When V = 40 and C = 0 are set, brightness reduction processing is performed and the overall contrast correction is not performed. When V = 100 and C = 0 is set, both brightness reduction processing and overall contrast correction are performed. I will not.

  Next, the printer driver sets AREA = 20 and STRENGTH = 2 (S58), and sharpens the gray data subjected to gradation conversion (S59). As a result, the contrast of the edge portion of the gray image whose lightness is at an appropriate low level is enhanced. Finally, the printer driver saves the adjustment parameters V, C, AREA, and STRENGTH, or saves the adjusted texture pattern (second camouflage pattern) data in the memory (S60).

  As described above, in the automatic texture pattern adjustment process, the lightness reduction process and the sharpening process are performed according to preset adjustment parameters.

  When automatic adjustment is performed for a composite camouflage pattern, brightness reduction processing and overall contrast improvement processing are performed when the composite camouflage pattern is a natural image such as a person, and for graphic images, brightness reduction processing is performed. It is desirable to perform a sharpening process.

  FIG. 34 is a diagram of an interface screen in the manual adjustment process of the texture pattern (second camouflage pattern) of FIG. The interface screen of FIG. 34 is a lower screen of the interface screen of FIG. 27, and transitions to this screen when the “texture pattern adjustment” button 137 of FIG. 27 is clicked.

  The texture pattern manual adjustment screen 150 includes an area 152 for selecting texture pattern data, a preview area 153 for the selected texture pattern, an area 154 for setting a lightness parameter V and a contrast parameter C, and parameters for sharpening processing. It has an area 155 for setting an AREA (range) and STRENGTH (intensity), and a preview area 156 for the adjusted texture pattern. The user can select a texture pattern in the area 152 and appropriately select and determine an adjustment parameter in the areas 154 and 155 while viewing the preview areas 153 and 156. Then, the adjustment parameters are saved by clicking the “OK” button.

  When the above texture pattern adjustment process is completed, a composite pattern with the first camouflage pattern is displayed in region 136 of FIG. Further, a tint block image reflecting the composite camouflage pattern is displayed on a tint block setting screen (not shown). Since the brightness and contrast of the texture pattern or the composite camouflage pattern are adjusted, even if the first camouflage pattern and the second camouflage pattern (texture pattern) arbitrarily acquired by the user, the original camouflage pattern of the background pattern It is possible to improve the design of the image, enhance the concealment of the original copy-forgery-inhibited pattern, suppress the deterioration of the recognition of the original print image of the original copy-forgery-inhibited pattern, and improve the distinguishability of the copy of the copy-forgery-inhibited pattern.

It is a figure which shows the example of a latent image of a tint block, and a camouflage pattern. It is a figure which shows the example of the original copy-forgery-inhibited pattern. It is a figure which shows the example of the copy of a background pattern. FIG. 4 is a further enlarged view of the enlarged view of the original in FIG. 2 and the enlarged view of the copy in FIG. 3. 1 is a diagram illustrating a configuration of a printing system including a tint block image forming apparatus according to the present embodiment. It is a flowchart figure which shows the production | generation procedure of the copy-forgery-inhibited pattern data in this Embodiment. It is a figure which shows the example of the input / output characteristic of the dither matrix for producing | generating the image of the background part BI of a tint block, and the latent image part LI. 5 is a diagram showing a background portion dither matrix 34. FIG. It is a figure which shows the latent image part dither matrix. It is a flowchart figure which shows the production | generation method of the copy-forgery-inhibited pattern image data in this Embodiment. It is a figure which shows the example of a tint block effect. It is a figure which shows the example of arrangement | positioning of a background pattern. It is a figure which shows an example of a camouflage pattern, and the example of a tint block image which employ | adopted it. It is a flowchart figure of a tint block image generation process in this Embodiment. It is a figure explaining the tint block image generation processing of FIG. It is a figure which shows an example of a latent image mask pattern. It is a figure which shows an example of a camouflage pattern. It is a figure which shows an example of a correction | amendment synthetic | combination camouflage pattern gradation value. It is a figure which shows an example of a tint block image with a camouflage pattern. An example of a tint block image in the case of a two-tone camouflage pattern is shown. It is a figure which shows an inappropriate copy-forgery-inhibited pattern image when employ | adopting arbitrary camouflage patterns. It is a flowchart figure of the production | generation process of the synthetic | combination camouflage pattern in the tint block production | generation process of FIG. It is a figure which shows the example of the texture registered beforehand among the 2nd camouflage patterns. It is a figure explaining a tint block image generation process. It is a figure which shows the example of the synthesized camouflage pattern. It is a figure which shows the example of a user interface screen in the tint block generation process (FIG. 10) by a printer driver. It is a figure which shows the example of a user interface screen of the synthetic | combination camouflage pattern production | generation process S19 by a printer driver. It is a figure which shows the tint block image formed using the camouflage pattern synthesize | combined by the example of FIG. It is a figure explaining the function which raises the fall of the brightness, and the whole contrast. It is a figure which shows the texture pattern which performed the contrast correction of the whole, and the brightness correction, the synthetic | combination camouflage pattern, and the tint block image using the same. It is a figure explaining the function which raises the contrast of the edge part of a texture pattern. It is a figure which shows the texture pattern and synthetic | combination camouflage pattern which performed contrast emphasis (sharpening) and brightness correction of the edge part, and a tint block image using the same. It is a flowchart figure of the automatic adjustment process of the texture pattern (2nd camouflage pattern) of FIG. It is a figure of the interface screen of the manual adjustment process of the texture pattern (2nd camouflage pattern) of FIG.

Explanation of symbols

16: Original 20: Copy LI: Latent image portion BI: Background portion 16X: Enlarged image of original 20X: Enlarged image of copy 33: Latent image portion dither matrix 34: Background portion dither matrix

Claims (12)

In a copy-forgery-inhibited pattern image generation program for causing a computer to execute a copy-forgery-inhibited pattern image generation process for generating copy-forgery-inhibited pattern image data composed of a latent image portion and a background portion, which are reproduced with different output densities,
The tint block image generation step includes:
Camouflage pattern to input a first camouflage pattern data, the by shading change region in the first camouflage pattern data is synthesized second camouflage pattern data larger than the first camouflage pattern data to generate combined camouflage pattern data A synthesis process;
Regarding the gradation value of the composite camouflage pattern data, latent image portion image data is generated based on the latent image portion screen in the region corresponding to the latent image portion, and based on the background portion screen in the region corresponding to the background portion. A computer-readable copy-forgery-inhibited pattern image generation program comprising: a copy-forgery-inhibited pattern image data generation step for generating background image data. In claim 1,
The camouflage pattern synthesizing step further includes an adjustment step of generating second camouflage pattern data adjusted by adjusting the gradation value of the second camouflage pattern data to a lower brightness than before the adjustment. A tint block image generation program for synthesizing the second camouflage pattern data thus obtained with the first camouflage pattern data. In claim 2,
In the adjustment step, the tint block image generation program further performs a contrast enhancement process for enhancing the contrast of the gradation value of the gradation value of the second camouflage pattern data. In claim 2,
In the adjustment step, the tint block image is further characterized by performing sharpening processing for enhancing the contrast of the gradation value of the edge portion of the second camouflage pattern for the gradation value of the second camouflage pattern data. Generation program. In any of claims 2, 3 and 4,
Further, the copy-forgery-inhibited pattern image generation program further comprising an adjustment camouflage pattern registration step of storing the adjusted second camouflage pattern data in a memory after the adjustment step. In any of claims 2, 3 and 4,
Further, the copy-forgery-inhibited pattern image generation program further comprising an adjustment parameter registration step for storing in the memory the adjustment parameter used for the adjustment in the adjustment step after the adjustment step. In claim 1,
The camouflage pattern synthesizing step further includes an adjustment step of generating adjusted camouflage pattern data adjusted by adjusting the gradation value of the synthetic camouflage pattern data to a lower brightness than before adjustment,
In the copy-forgery-inhibited pattern image data generation step, the adjusted composite camouflage pattern data is used as the composite camouflage pattern data. In claim 1,
The synthesis of the camouflage pattern is a synthesis that achieves at least one of lowering the density of the synthetic camouflage pattern than that of the first camouflage pattern or increasing the contrast of the synthetic camouflage pattern as compared with the first camouflage pattern. A tint block image generation program characterized by performing an operation. In claim 1,
The copy-forgery-inhibited pattern image generation program, wherein the second camouflage pattern data is multi-gradation image data exceeding two gradations. In claim 1,
The camouflage pattern synthesizing step further generates modified second camouflage pattern data in which the second camouflage pattern is reduced and repeatedly arranged, and the modified second camouflage pattern data is converted into the first camouflage pattern data. A tint block image generation program characterized by combining. In a copy-forgery-inhibited pattern image generation device that generates copy-forgery-inhibited pattern image data composed of a latent image portion and a background portion that have different output densities reproduced during copying,
The first camouflage pattern data is input, and the first multi-grayscale camouflage pattern data is combined with the second camouflage pattern data in which the shade change region is larger than the first camouflage pattern data to generate the composite camouflage pattern data. Camouflage pattern synthesizing means,
Regarding the gradation value of the composite camouflage pattern data, latent image portion image data is generated based on the latent image portion screen in the region corresponding to the latent image portion, and based on the background portion screen in the region corresponding to the background portion. A tint block image generation apparatus comprising a tint block image data generation unit configured to generate background image data. In claim 11 ,
The camouflage pattern synthesizing means further generates second camouflage pattern data adjusted by adjusting the gradation value of the second camouflage pattern data to a lower brightness than before adjustment, and the adjusted second camouflage pattern data is generated. A tint block image generating apparatus, wherein the camouflage pattern data is combined with the first camouflage pattern data.