JP7665147B2 - Method and program for creating printed matter - Google Patents

Description

The present invention relates to a method and program for creating printed matter that requires anti-counterfeiting and anti-tampering functions in the field of security printed matter such as banknotes, passports, securities, identification cards, cards, and travel tickets that require anti-counterfeiting effects.

In recent years, with the improvement of image quality in color copiers and the computerization of color plate-making technology, the methods of counterfeiting gift certificates and securities have tended to become more diverse. In particular, the resolution of image input/output devices used in the printing industry has improved significantly, making it relatively easy to extract thin lines and minute characters used on securities.

As a result, it has become possible to extract with high accuracy using input/output devices such as scanners the background patterns, color patterns, relief patterns, and other patterns that are composed of thin lines and are used in many of today's securities. This has led to an increase in more authentic counterfeit products that make extensive use of spot color plates, rather than simply counterfeits made using general commercial printing methods that consist of CMYK four-color halftone dots.

The applicant has therefore filed a patent application for a halftone print, which is characterized by having a visible image formed on a substrate by a first halftone area (1) consisting of a first halftone dot portion using a first ink having a first characteristic, a latent image consisting of a second halftone dot portion using a second ink having a second characteristic different from the first characteristic, and a second halftone area (2) consisting of a visible image formed by a third halftone dot portion using a first ink of the same color as the second ink having the first characteristic, formed adjacent to the first halftone area (1) (see, for example, Patent Documents 1 to 3).

The applicant has also filed a patent application for a method and program for producing the aforementioned halftone print, which includes an image input means for inputting a first image that is the basis for a first continuous tone image to be recognized as a visible image and a second image that is the basis for a second continuous tone image that is recognized as a latent image only under specific observation conditions, a setting item setting means for setting the resolution, coloring, and halftone dot shape of the halftone dot data for each setting item, and a calculation means for generating a first continuous tone image and a second continuous tone image from the first image and the second image input by the image input means, respectively, and synthesizing the generated first continuous tone image and second continuous tone image, as well as a program for executing the device (see, for example, Patent Document 4).

Patent No. 3544536 Patent No. 4461234 Patent No. 5707595 Patent No. 4958117

However, in the technologies of Patent Documents 1 to 4, there existed conditions under which the latent image would not be concealed by the second halftone region (2) composed of a second ink (e.g., an infrared-absorbing ink (K (black)) (2a)) and a first ink (e.g., an ink not having infrared absorption (CMY (cyan, magenta, yellow) (2b)) depending on the combination of printing conditions (halftone resolution, halftone processing method, type of ink), design and print density of the visible image and latent image. Therefore, there was an issue that the latent image would be visible when a part of the visible image with flat density was combined with a part of the latent image with large changes in density.

In addition, in order to conceal the latent image so that it was not visible to the naked eye, it was necessary to repeat the process of adjusting the density of the visible image, adjusting the density of the latent image, printing, and visually checking it, through trial and error. As a result, there were issues such as poor concealment of the latent image and limitations on the design of the visible and latent images.

Even when optimal conditions were obtained through the above-mentioned trial and error, the latent image may not be concealed if the conditions of use of the printed matter, such as the light source used when viewing or the type of substrate, are different.

The present invention aims to solve the above-mentioned problems, and provides a method and program for producing a printout with good concealment of the latent image by changing the density of the latent image according to the visible image, and with good concealment of the latent image even when the printout is used under different light sources or printed on different substrates.

The present invention is a method for creating a printout in which a latent image visible under specified observation conditions and a visible image visible under a visible light source formed to conceal the latent image are formed, and the same corner of the visible image and latent image are set as reference coordinates, and the coordinate diagonal to the reference coordinates is set as the final coordinate. Visible original image data and latent original image data are created by regularly adding pixels and densities from the reference coordinates for the area from the reference coordinates to the final coordinates, and the coordinates of at least three points that are common positions of the visible original image data and the latent original image data are set as reference points, and a sample is created based on patch print data synthesized by overlapping the reference points. This method for producing a printed matter comprises a patch printing step of printing on a substrate to produce a patch print, an evaluation table creation step of creating an evaluation table for the patch print that indicates whether the latent image is concealed or not for combinations of pixels and densities of the visible image and the latent image under a plurality of different visible light sources, and a selection step of using the evaluation table to select a combination of densities that allows the latent image to be concealed by the visible image, creating latent image data based on the densities of the selected latent image original image data, and printing on the substrate using print data that combines the latent image data and the visible original image data.

The present invention is a program for creating printed matter that causes a computer to execute a method for creating printed matter.

By changing the density of the latent image according to the visible image, the present invention improves the visibility of the latent image and can create a printout with good concealment of the latent image even when the printout is used under different light sources or printed on a different substrate.

FIG. 1 is a diagram showing an example of a halftone print to be produced according to the present invention. 1 is a diagram illustrating an example of a method for producing a printed matter and a program for producing a printed matter according to the present invention; FIG. 13 is a diagram illustrating an example of a patch printing process. FIG. 2 is a diagram showing an example of visible original image data. FIG. 2 is a diagram showing an example of original latent image data; FIG. 13 is a diagram showing an example of a patch print in which a visible image and a latent image are combined. FIG. 13 is a diagram illustrating an example of an evaluation table creation process. FIG. 13 is a diagram illustrating an example of a table. An example showing the density of a patch print FIG. 13 is a diagram illustrating an example of a selection process. FIG. 2 is an example diagram showing visible original image data according to the first embodiment. FIG. 4 is an example diagram showing original latent image data according to the first embodiment; FIG. 4 is an example diagram showing patch print data according to the first embodiment; FIG. 13 is a diagram illustrating an example of an evaluation table according to the first embodiment. FIG. 1 is an example diagram showing data of Example 1. 13 shows images of a halftone print observed under two different light sources. FIG. 1 is a diagram illustrating an example of a printed matter. FIG. 13 is a diagram illustrating an example of synthesis using a reference point.

The following describes the embodiments of the present invention with reference to the drawings. However, the present invention is not limited to the embodiments described below, and various other embodiments are included within the scope of the technical ideas described in the claims.

The present invention can be applied to various printed matter (10) in which a latent image (14) and a visible image (13) are formed adjacent to each other, as shown by the diagonal lines in Figures 17(a) and (b) for convenience, but will be described using the halftone dot print (A1) shown in Figure 1 as an example. Figure 1(a) is a schematic diagram of the halftone dot print (A1), and Figure 1(b) is a partially enlarged view showing the configuration of the halftone dots in the halftone dot print (A1). The configuration of the halftone dots shown in Figure 1(b) will be described below. Note that in this specification, adjacent means that at least a portion of two adjacent areas, lines, or halftone dots are in contact.

(Dot Composition)
The halftone dot configuration is such that a first halftone region (1) which is a first region and a second halftone region (2) which is a second region are used as basic units, and a plurality of first halftone regions (1) are regularly arranged so that the first halftone region (1) surrounds the second halftone region (2). When a plurality of first halftone regions (1) and second halftone regions (2) are arranged, the shapes of the regions may be the same or different, and it is sufficient that at least a portion of the regions is arranged adjacent to each other. In consideration of the visibility of the latent image, it is more preferable that the regions have the same shape and are arranged adjacent to each other without any gaps.

(First Halftone Area)
The first halftone regions (1) are all of the same shape, and may be polygonal, circular, or geometric, but are more preferably square or rectangular. The first halftone region (1) is composed of an image forming portion (1a) and a first background portion (1b). By arranging a plurality of first halftone regions (1), a first continuous tone image is formed that is recognized as a visible image on a printed matter.

(Second Halftone Area)
The second halftone regions (2) are all of the same shape, and may be polygonal, circular, or geometric, but are preferably square or rectangular. The second halftone regions (2) are composed of an image portion (2a) and a second background portion (2b). By arranging a plurality of second halftone regions (2), a second continuous tone image is formed that is recognized as a latent image on the printed matter only under specific observation conditions.

The inks used to form the halftone print (A1) are inks having different characteristics for each of the image forming portion (1a) and first background portion (1b) of the first halftone region (1) and the image portion (2a) and second background portion (2b) of the second halftone region (2). For example, when the image forming portion (1a) and the first background portion (1b) of the first halftone region (1) and the second background portion (2b) of the second halftone region (2) are formed with CMY inks that do not absorb infrared rays, and the image portion (2a) of the second halftone region (2) is formed with black ink (K) that absorbs infrared rays, a halftone print (A1) is obtained in which a first continuous tone image (8) formed by the image forming portion (1a) and the first background portion (1b) of the first halftone region (1) appears under a visible light source as shown in Fig. 16(a), and a second continuous tone image (9) formed by the image portion (2a) of the second halftone region (2) appears under an infrared light source, which is a different observation condition, as shown in Fig. 16(b). The technology used in this halftone print (A1) is "ImageSwitch (trademark registration number 4718813)". In this specification, the different characteristics include the presence or absence of infrared absorption characteristics, the presence or absence of light emission characteristics, the presence or absence of solvent characteristics, etc.

First Embodiment
As shown in FIG. 2, the print creation method and print creation program of the present invention comprise a patch printing process (S1) in which the density of each of the visible original image data (3) and the latent original image data (4) is changed, and a patch print (5) is created by combining the density-changed visible original image data (3) and the latent original image data (4), an evaluation table creation process (S2) in which an evaluation table is created from the patch print (5) that evaluates whether or not the latent image is concealed when visually observed for combinations of the densities of the visible image and the latent image, and a selection process (S3) in which a density at which the latent image can be concealed is selected from the density of the visible image using the evaluation table, and printing is performed.

In this specification, an embodiment is shown in which the visible original image data (3) is a printed matter in gray tones, but it can be applied to color as well. As shown in Figure 1, the image in this invention is expressed with the upper left corner of the image as the origin (0,0), the horizontal (width) direction as X, and the vertical (height) direction as Y, and the coordinates (position) are expressed as X, Y. Images are composed of pixels, which are the smallest units that can be expressed by a computer, and each pixel has a brightness, which is expressed as density in this specification.

Density (brightness) is expressed as a gradation value from 0 to 255, with 255 being brighter (whiter, paler). Colors are expressed as RGB (red, green, blue) densities (0 to 255), and in the case of gray gradations, the RGB gradation values are all the same value. Additionally, the CMYK densities in an image are expressed as 0 to 100%, with the higher the percentage value, the darker it is. For K, 0% is white and 100% is black. Additionally, densities are basically expressed as RGB densities, and in the case of CMYK, they are expressed as %. Next, each process will be explained in detail.

(Patch printing process)
The patch printing step (S1) is a step of creating patch printing data by combining the visible original image data (3) and the latent original image data (4) in which the densities of the visible original image data (3) and the latent original image data (4) are changed, and printing the created patch printing data on a sample substrate such as medium-quality paper, fine paper, or coated paper to create a patch print (5) for confirming whether or not the latent image is concealed from the visible image under a plurality of different visible light sources such as LED, fluorescent lamp, incandescent lamp, etc. The sample substrate is a known material such as medium-quality paper, fine paper, or coated paper for forming the patch print (5), and is a material that serves as an optimum substrate for evaluating the patch print (5) as described below based on the sample substrate and forming the final print based on the sample substrate.

The process (S1-1) of creating the visible original image data (3) involves initializing the allocation of the area (width, height) of the visible original image data (3) forming the visible image, the coordinates (X, Y), the density, and the density step (change) in the Y direction. After the initialization, the area from the reference coordinates ( _X0 , _Y0 ) of the visible original image data (3) to the coordinates ( _XZ , _Yn ) is filled with a solid color with a density (0). The reference coordinates ( _X0 , _Y0 ) are one corner of the visible original image data (3), and in FIG. 4, the upper left corner is set as the reference coordinates ( _X0 , _Y0 ). Next, the pixel (+ _n ) and density (+m) are regularly added to the coordinate (Y0) in the Y direction to change the filling density, and the area from the coordinates ( _X0 , Y0 _+n ) to the specified coordinates ( _XZ , Y0 _+n ) is filled with a solid color with a density (T+m). By repeating this operation up to the final coordinates ( _Xz , _Yz ), it is possible to obtain visible original image data (3) in which the density changes stepwise in the vertical direction (Y), as shown _in Fig. 4. The size of the area to be filled in is set appropriately. The final coordinates (Xz, _Yz ) are a corner of the visible original image data (3) that is diagonal to the corner set as the reference coordinates ( _X0 , _Y0 ).

Next, the process (S1-2) of creating the latent image original image data (4) will be described. In this first embodiment, for the sake of convenience, characters are used as images to distinguish from the visible original image data (3), but there is no particular limitation to patterns, symbols, etc. In the process (S1-2) of creating the latent image original image data (4), first, an image area of the same size as the visible original image data (3) is secured (width, height), and the coordinates (X, Y), density, and density step (change) in the X direction are initialized. After the initialization, characters are created with a density of 0 in the area from the reference coordinates ( _X0 , _Y0 ) of the latent image original image data (4) to the coordinates ( _Xz , _Yn ). Note that the reference coordinates ( _X0 , _Y0 ) of the latent image original image data (4) are set to the same corner as the reference coordinates ( _X0 , _Y0 ) of the above-mentioned visible original image data _{(3 )} . For example, in FIG. 5, the upper left corner, which is the same as that of the visible original image data (3), is set as the reference coordinate ( _X0 , _Y0 ). The number of characters is created so that they fit within the solid part of the visible original image data ( ₃ ) with the same density. The density within the character is the same density. Next, characters are created with density (T+m) in the area from coordinate (X0 _+n , _Y0 ) to a specified coordinate ( _XZ , _Yn ), which is obtained by adding pixels (+n) and density (+m) to the coordinate (X0) in the X direction (S1-2). By repeating this operation up to the final coordinate ( _XZ , _YZ ), it is possible to obtain latent original image data (4) in which the density changes in the horizontal direction (X direction) as shown in FIG. 5. Note that the final coordinate ( _XZ , _YZ ) is a corner that is diagonal on the latent original image data (4) to the corner set as the reference coordinate ( _X0 , _Y0 ).

In the synthesis step (S1-3), the created visible original image data (3) and latent original image data (4) are synthesized to create patch print data, and the created patch print data is used to print a visible image with a first ink visible under a visible light source and a latent image with a second ink that is the same color as the first ink under a visible light source and is visible under a non-visible light source (infrared, ultraviolet) on a sample substrate to create a patch print (5) shown in Fig. 6 (S1-4). Note that the synthesis of the visible original image data (3) and the latent original image data (4) is performed by superimposing the coordinates of at least three arbitrary points from the coordinates ( _X0 , _Y0 ) to the coordinates ( _XZ , _Yn ), which are common positions in each data, as reference points in the visible original image data (3) and the latent original image data (4), respectively. For example, as shown in FIG. 18, the reference points (P1, P2, P3) of the visible original image data (3) are combined with the reference points (P1', P2', P3') of the latent original image data (4).

In addition, when forming the halftone dot configuration shown in Figure 1 (b), each data of the image forming portion (1a) and the first background portion (1b) of the first halftone region (1), and each data of the image portion (2a) and the second background portion (2b) of the second halftone region (2) are formed using the latent image original image data (4), and the coordinates of at least three arbitrary points from the coordinates ( _X0 , _Y0 ) to the coordinates ( _Xz , _Yn ), which are common positions in the data forming the first halftone region (1) and the data forming the second halftone region (2) using the latent image original image data (4), are used as reference points in the visible original image data (3) and the latent image original image data (4), and the reference points are overlapped and synthesized so that multiple reference points are regularly arranged so that the first halftone region (1) surrounds the second halftone region (2), thereby creating patch print data.

Next, using the created patch print data, the image forming portion (1a) and the first background portion (1b) of the first halftone area (1) and the second background portion (2b) of the second halftone area (2) are formed using CMY inks that do not absorb infrared light, and the image portion (2a) of the second halftone area (2) is printed on the aforementioned sample substrate using black ink (K) that absorbs infrared light to create the patch print (5).

The patch printing process (S1) shown in Figure 3 shows a method in which there is one patch print (5). When increasing the number of gradations of black or when there are many colors, the patch printing process (S1) is performed multiple times to create multiple patch prints (5) for each color. Note that when there are many types of sample substrates, a patch print (5) is created for each type of sample substrate.

(Evaluation table creation process)
In the evaluation table creation step (S2), as shown in Fig. 7, the created patch print (5) is checked visually or with an optical device such as a camera for the latent image (one character at a time in this embodiment) under a plurality of different visible light sources such as the above-mentioned LED, fluorescent lamp, incandescent lamp, etc., to check whether the latent image is concealed by the visible image at each density and under each light source, evaluate the density combinations for concealment or not, and input the evaluation results into the evaluation table (6) shown in Fig. 8. Furthermore, when a patch print (5) is created for each type of sample substrate, an evaluation table (6) is created for each type of sample substrate.

The evaluation table (6) inputs the numerical values of the density combinations where the latent image can be confirmed, that is, the density combinations where the latent image is not concealed by the visible image. For example, as shown in FIG. 9, the numerical values are assigned points for each type of visible light source such as LEDs and fluorescent lights, and the sum of these numerical values indicates that the latent image is not concealed. The dotted area (7') where the number is 1 or more is the density (7') where the latent image is not concealed, and the thick area (7) where the number is 0 means that the latent image is concealed by all of the multiple light sources.

In addition, the patch print (5) in the evaluation table creation process (S2) may be checked using an optical device such as a color camera instead of a human. When checking with a color camera, one patch print (5) is imaged by switching between multiple light sources in the same way as visual inspection, and the average value of the gradation value of a certain area of the area without a latent image and the average value of the gradation value of a certain area of the area with a latent image are calculated for the captured image, and the average values are compared.

If the comparison reveals a difference of a certain gradation value or more, it is determined that the image is not concealed (is visible to the human eye) and is recorded in the evaluation table (6). The recording method is the same as for visual inspection, and the evaluation table creation step (S2) may be automated by processing this method by a program. It is also possible to use average values and correlation coefficients as a comparison method for evaluation.

(Selection process)
In the selection step (S3), as shown in Fig. 10, the evaluation table (6) is used to select the density at which the latent image is concealed relative to the density of the visible image, and printing is performed. In detail, as shown in Fig. 9, the evaluation table (6) is searched for combinations in which the latent image is concealed by the visible image under all visible light sources and/or on all sample substrates, and these are selected (S3-1) as the density of the visible image concealed under all light sources and the maximum density (A) of the latent image.

Next, latent image data is created in which the latent image has the maximum density (A), or latent image data is created by converting the original latent image data (4) to the selected maximum density (A) (S3-2). There are several density conversion methods, such as a method using a tone curve or a method using a lookup table, but in this first embodiment, linear density conversion, in which the tone curve is a straight line, is used. Note that linear density conversion is a process in which the density (tone value) of an image is converted from a specific range to a different range, and is shown in the following formula 1.

Here, X is the value of one pixel in the source image, Y is the value of one pixel in the destination image, Ymax is the maximum pixel value in the source image, Xmin is the minimum pixel value in the source image, Ymax is the maximum pixel value in the destination image (A in Example 1), and Ymin is the minimum pixel value in the destination image (0 in Example 1).

In the first embodiment, as an example of the selection step (S3), the density of the latent image is converted to the maximum density (A) using a density conversion method, but a known method may be used to calculate the average value of one pixel of the visible image corresponding to the same position (coordinate) as one pixel of the latent image and/or its surrounding pixels, search for the maximum density (A) at which the latent image is concealed, and change it to the maximum density (A) of the latent image.

Alternatively, as another known technique, blurring may be performed only on portions of the latent image that are not concealed, and the density of the latent image may be changed to a maximum density (A) depending on the intensity of the edge image obtained by blurring the density of the latent image. Alternatively, edge extraction may be performed on the visible image, and the density of the latent image may be changed to a maximum density (A) depending on the intensity of the edge image obtained by blurring the density of the visible image.

In the first embodiment, the density of the latent image is changed to match the density of the visible image, but the density of the visible image may also be changed to match the density of the latent image.

Next, the visible original image data (3) is combined with the latent image data converted to density (A) in the same manner as in the above-mentioned method of combining the visible original image data (3) and the latent original image data (4) to create print data (S3-3), and the created print data is used to create a print on a substrate that can conceal the latent image, similar to the sample substrate.

In the case of forming the halftone dot configuration shown in FIG. 1(b), the data forming the first halftone area (1) based on the visible original image data (3) is similarly synthesized with the data forming the second halftone area (2) converted to density (A) to create print data, and the halftone dot print (A1) shown in FIG. 1 is created on the substrate.

(program)
The present invention also provides a program for causing a computer to execute the method for producing a printed matter.

The following describes an example in which a halftone print (A1) shown in FIG. 1 was created based on the print creation method according to the above embodiment. However, the content of the present invention is not limited to the scope of the example shown below.

Example 1
In Example 1, a digital color copier RICOH Pro7100S (printing resolution 600 DPI) manufactured by RICOH Corporation was used as the printer, and wood-free paper was selected as the sample substrate and substrate. The inks forming the halftone print (A1) were CMY inks that do not absorb infrared rays for the image forming portion (1a) and the first background portion (1b) of the first halftone region (1) and the second background portion (2b) of the second halftone region (2), and black ink (K) that absorbs infrared rays for the image portion (2a) of the second halftone region (2).

The visible original image data (3) shown in FIG. 11 was created by regularly adding density from the reference coordinates (0,0) of the origin to the final coordinates (2349,105) of the diagonal to the reference coordinates. Similarly, the latent original image data (4) shown in FIG. 12 was created by regularly adding density from the reference coordinates (0,0) of the origin to the final coordinates (2349,105) of the diagonal to the reference coordinates.

In the synthesis process (S1-3), first halftone area data that forms the image formation portion (1a) and first background portion (1b) of the first halftone area (1) is created using the visible original image data (3), and second halftone area data that forms the image portion (2a) and second background portion (2b) of the second halftone area (2) is created using the latent original image data (4). The coordinates of three points that are common positions in each data are used as reference points in the first halftone area data and the second halftone area data, and the reference points are superimposed and synthesized to create patch printing data (not shown).

Next, the image forming portion (1a) and the first background portion (1b) of the first halftone region (1) were created using CMY inks, and the second background portion (2b) of the second halftone region (2) was created with 100% CMY concentration using CMY inks that do not absorb infrared light. The image portion (2a) was also created using black ink (K) that absorbs infrared light. Next, the first halftone regions (1) were regularly arranged in multiple places so as to surround the second halftone region (2), and a patch print (5) as shown in Figure 13 was created on high-quality paper, which is the sample substrate.

Next, the evaluation table (6) is created by checking each character of the created patch print (5) visually or with an optical device such as a camera under three different visible light sources: a D65 light source, an LED light source, and a fluorescent light, and extracting density combinations in which the latent image is not concealed by the visible original image.

The numerical rating indicates the sum of all visible values, with 0 being invisible under all light sources, 1 being visible under D65 light source, 2 being visible under LED light source, and 4 being visible under fluorescent light.

As shown in Figure 14, the evaluation results are as follows: if it is visible with all light sources, the total value will be a maximum of 7; if it is visible with both an LED light source and a fluorescent light, it will be rated as 6; if it is visible with both a D65 light source and a fluorescent light, it will be rated as 5; if it is visible with both a D65 light source and an LED light source, it will be rated as 3; and the numerical values for each of the other individual light sources will also be evaluated.

Next, the maximum density (A) of the latent image is selected by searching for an area where the density of the latent image is concealed in all visible image densities using the evaluation table (6) shown in FIG. 14, and the area (7) surrounded by a dotted line where the density is 244 to 255, which is a value of 0 and therefore invisible to all light sources, is set as the maximum density (A).

Next, the latent image original image data (4) is converted using a linear density conversion using a tone curve so that the density of the latent image original image data (4) becomes the maximum density (A) of 244 to 255, and the latent image original image data (4) converted to the maximum density (A) is used to create the second halftone area data (15) shown in Figure 15 (a).

Next, the first halftone area data (16) shown in FIG. 15(b) was created using the visible original image data (3), and the second halftone area data (15) converted to density (A) was synthesized and embedded to create print data (not shown). The halftone dot print (A1) shown in FIG. 1 was printed on high-quality paper, and when it was checked using a D65 light source, an LED light source, and a fluorescent lamp, the latent image was not visible under any of the light sources, and it was confirmed that it was concealed. When checked under an infrared light source, only the latent image was visible.

A1 halftone print 1 first halftone area 1a image formation portion 1b first background portion 2 second halftone area 2a image portion 2b second background portion 3 visible original image data 4 latent original image data 5 patch print 6 evaluation table 7 area where latent image is concealed 7' area where latent image is not concealed 8 first continuous tone image 9 second continuous tone image 10 print 11 visible image data 12 latent image image data 13 visible image 14 latent image 15 second halftone area data 16 first halftone area data

Claims (2)

A method for producing a printed matter on which a latent image visible under a predetermined observation condition and a visible image visible under a visible light source formed so as to conceal the latent image are formed, comprising the steps of:
a patch printing step of setting the same corner of said visible image and said latent image as a reference coordinate, setting the coordinate diagonally opposite to said reference coordinate as a final coordinate, creating visible original image data and latent original image data by regularly adding pixels and densities from said reference coordinate for an area from said reference coordinate to said final coordinate, setting the coordinates of at least three points that are common positions of said visible original image data and said latent original image data as reference points, and printing on a sample substrate based on patch print data that is synthesized by overlapping said reference points to create a patch print;
an evaluation table creation step of creating an evaluation table showing whether the latent image is concealed or not for a combination of the pixels and densities of the visible image and the latent image under a plurality of different visible light sources for the patch print;
a selection step of using the evaluation table to select the combination of densities that enables the latent image to be concealed by the visible image, creating latent image data based on the selected densities of the latent image original image data, and printing on a substrate using print data that is a combination of the latent image data and the visible original image data. A program for creating a printed matter that causes a computer to execute the method for creating a printed matter described in claim 1.

Images