JP2022146971A - Method and software for generating latent image printing data - Google Patents

Abstract

To provide a method and software for generating latent image printing data for obtaining a latent image printout having good print quality regardless of the maker or model of a printer.SOLUTION: The invention relates to a method and software for generating data for a latent image printout in which an invisible image is visible under infrared light. An RGB image data is formed by forming pseudo-black, pseudo-cyan, pseudo-magenta, and pseudo-yellow patterns expressed in the RGB color space without overlapping each other.SELECTED DRAWING: Figure 4

Description

The present invention relates to security printed matter that requires anti-counterfeiting and anti-tampering functions such as passports, securities, identification cards, other certificates, important documents, tickets, cards, etc. The present invention relates to a method and software for creating latent image print data that requires originality and security by outputting data from a wide variety of printers, including general household printers, without using

2. Description of the Related Art For printed materials such as passports, securities, identification cards, other certificates, important documents, tickets, cards, etc., it is important to impart anti-counterfeiting and tampering effects to the printed materials to ensure high security. As a general method for imparting an anti-counterfeiting and tampering effect to these printed materials, there is a method in which an invisible image that cannot be visually recognized appears by adding some means and action to the printed material. Typical examples include the addition of functional inks that cannot be reproduced normally by color copiers, and the method of applying copy-preventive lines, which are composed of lines that cannot be reproduced by copying, to printed matter. There is

However, in recent years, the performance of color copiers has been improved, and the resolution of copies and the reproducibility of images have been improved. In addition, the use of functional ink such as fluorescent ink, which is invisible under normal light, for printed matter has an anti-counterfeiting effect because fluorescent ink materials have become commercially available and easily available to everyone. is declining.

In order to solve the above-mentioned problems, the present applicant has proposed a counterfeit countermeasure for copying using a high-resolution copying machine without using a special base material or ink. A patent application has been filed for a latent image printed matter in which a toned image is visually recognized and a different gradation image (latent image) can be visually recognized when observed using an infrared camera (see Patent Document 1).

The latent image printed matter described above can be printed in large quantities continuously using an offset printing machine or the like, or printed as needed by a printer. When printing using an offset printing machine or the like, since the CMYK data in the data creation can be printed directly, the black (K) ink that becomes the latent image and the cyan (C) and magenta (M) ink that becomes the gradation image are prepared in advance. ), and yellow (Y) ink. do not have.

On the other hand, in recent years, the development of the IT environment has progressed, and computers and printers are in place as an infrastructure. A method of obtaining a latent image printed matter by applying it and outputting it with a printer using a network is attracting attention. However, there are various problems when creating a latent image print with a printer.

The first is low image resolution. In Patent Document 1, a visible image area (a) and an invisible image area (b) are arranged in a matrix with a desired positional relationship, like a printed pattern portion (2a) shown in FIG. 9(a). The visible image area (a) is printed with cyan (C), magenta (M) and yellow (Y) toners or pigment inks that do not contain infrared absorbing dyes, and the invisible image area (b) is printed with cyan ( In addition to C), magenta (M) and yellow (Y), it is printed with black (K) toner containing an infrared absorbing pigment, pigment ink, or the like. The continuous gradation of the invisible image (5) can be represented by the image line area of black (K) in the invisible image area (b).

At this time, in order to maintain the image resolution of the invisible image forming continuous gradation, it was necessary to keep the number of pixels of the invisible image area (b) to the minimum necessary. However, in a low-resolution output device, sufficient pixels cannot be set to provide continuous gradation, and the image resolution remains within the range that the output device can handle. For example, in a color printer with an output resolution of 600 dpi, the invisible image area (b) must have at least 4 pixels in length and width in order to provide an invisible image of 16 gradations. The number was an image resolution equivalent to 60 lines/inch.

Further, the document file forming the streak structure of the technique described in Patent Document 1 is basically a 32-bit CMYK image, and cyan (C) and magenta ( M), yellow (Y), and black (K) are required to be printed as they are. That is, it has been limited to expensive color multifunction machines and digital printers equipped with a printer driver that can turn off color separation in the output device.

On the other hand, when an inexpensive home printer is used, black and gray are produced by mixing four color toners of cyan (C), magenta (M), yellow (Y) and black (K), or pigment ink. can also be expressed, but it is possible to print with only black (K), so the control system of the printer driver removes equal amounts of three colors, cyan (C), magenta (M), and yellow (Y) from the black portion, and For this reason, a UCR method (Under Color Removal) is generally used in which the amount of the black (K) component is increased. Therefore, as shown in FIG. 9B, the visible image area (a) is printed in cyan (C), magenta (M) and yellow (Y), while the invisible image area (b) is printed in black. If only (K) is printed, the entire invisible image area (b) will be colored, and the line shape of the invisible image (5), which was originally composed of black (K) of the 32-bit CMYK image, cannot be expressed. There is a problem that the latent image cannot be visually recognized when the latent image printed matter is observed by infrared rays.

The second problem is uneven print quality due to differences in printer manufacturers and models. A wide variety of printer models are sold by various manufacturers, and many printer control methods, control programs, printer drivers, etc. are independently developed by each manufacturer. There were times when there was a difference in print quality. For example, when the same print image data is input to an image processing device such as a computer and output by printers of different manufacturers, models, and models, the printed images printed by each printer will have different densities and hues. had been printed.

If this is caused by the toner density, color balance, output method, etc. of each printer, the density and hue can be adjusted by changing the output settings already provided in the printer. However, the third problem is uneven print quality due to data conversion in personal computer processing. Specifically, in Windows (registered trademark), MacOS, etc., the RGB color gamut is supported as a standard color gamut at the OS level. is converted. When data created by a personal computer is output to a printer, the data in the RGB color space is re-converted to CMYK data. .

In addition, some simple household printers and mobile printers that operate on rechargeable batteries can only input RGB data. In some cases, the color tone of the printed data differs from the density and hue of the printed image that is output.

As described above, variations in print quality (printed image density and hue) output from a printer not only result in unintended colors when data is created, but also when latent image prints are observed under infrared light. In other words, when the printed matter is observed with the naked eye under normal light, a latent image that should not be visually recognized is visible. In addition to that, there is also the problem that variations in printed matter quality affect the authenticity determination of printed matter.

Therefore, the applicant of the present invention aims to print a proper latent image even in a printer of a print control system for color-converting image data. As a method of creating halftone dot prints characterized by being divided and arranged in predetermined areas, CMYK data is converted into the three primary colors of light (RGB) and processed as an sRGB color gamut without using a color management function. (See, for example, Patent Document 2). .

In order to solve the same problem, another publicly known technology is a printing control method that combines K, which is an encoded pattern, and CMY, which is graphic information. A technique is disclosed in which at least one of the RGB component values is mapped below the mixture threshold of the corresponding CMY component in order to prevent the K component from being used for printing graphic information. (See Patent Document 3, for example).

As another technique, a specific printer driver capable of printing data in a CMYK color space without once converting it to data in another color space is automatically selected from among a plurality of printer drivers, and A technology that automatically selects a high-definition mode as the print mode for printing without first converting data in the CMYK color space to data in another color space, and prints a document to be printed with an identification image added. There is (for example, see Patent Document 4).

Japanese Patent No. 3544536 Japanese Patent No. 4214262 Japanese Patent No. 5564498 Japanese Patent No. 4506345

However, the technology disclosed in Patent Document 2 could be applied to expensive color multi-function machines and digital printers equipped with an output device that can print each color information of CMYK as it is and a printer driver that can set color separation in the output device to off. , Simple household printers that can only input RGB data and mobile printers that operate on rechargeable batteries, when CMYK data is input, it is forcibly converted to RGB data and printed again with CMYK data on the printer. However, even if this technology is used, the color of the data for printed matter may not be reproduced as it is in the printed matter.

The technique of Patent Document 3 is a color control method by a printer. In order to prevent the K component from being used for printing graphic information (CMY), Mapping is used, but since the hue of the printed graphic information is affected by the mapping, it is difficult to reproduce the color at the time of creation as it is in the printed matter.

The technique of Patent Document 4 is also a printer control method for the purpose of preventing data conversion to another color space. I had to. As mentioned above, printer control methods, control programs, printer drivers, etc. are often independently developed by each manufacturer, so the issue of differences in print quality between printers remains unsolved. was

In particular, in recent years, the usage environment of printers by users has been diversified, and while there are various manufacturers and models, simple printers for general households without special control functions and mobile printers that operate on a rechargeable battery are the most common. However, it has been required to be able to print latent image prints with good print quality.

In view of the above circumstances, the present invention provides good print quality (concealability of latent images when observed with the naked eye, visibility of latent images when observed with infrared vision, printed matter regardless of the manufacturer or model of the printer). The object of the present invention is to provide a method and software for creating data for latent image printed matter for obtaining latent image printed matter having the sharpness of .

The present invention is a method for creating printing data for a latent image printed matter in which an invisible image is visually recognized under infrared light, wherein first image data serving as a base image of the invisible image is obtained, and black and white (monotone) data is obtained. obtaining RGB image data; inverting black and white (monotone) RGB image data to obtain negative image data; adjusting tone curves of black and white (monotone) RGB image data and the negative image data; The black and white (monotone) RGB image data after tone curve adjustment is formed by a pseudo-black pattern expressed in the RGB color space, and the negative image data is converted into three pure primary colors of cyan, magenta, and yellow in the RGB color space. forming by the represented pseudo-cyan, pseudo-magenta and pseudo-yellow patterns, forming the pseudo-black, pseudo-cyan, pseudo-magenta and pseudo-yellow patterns without overlapping each other; and synthesizing each pattern of pseudo-yellow.

Further, the present invention provides a method for creating printing data for a latent image printed matter in which a visible image is visually recognized with the naked eye under normal light and an invisible image is visually recognized under infrared light, wherein a base image of the invisible image is a step of obtaining black and white (monotone) RGB image data, a step of inverting the black and white (monotone) RGB image data to obtain negative image data, a step of obtaining negative image data, and a black and white (monotone) RGB image a step of adjusting tone curves of the data and the negative image data; a step of obtaining second image data as a base image of the visible image to obtain RGB image data of the visible image; and a tone curve of the RGB image data of the visible image. a step of synthesizing the RGB image data of the visible image after the tone curve adjustment with the negative image data after the tone curve adjustment to obtain synthesized image data; and a black and white (monotone) RGB image after the tone curve adjustment. The data is formed by a pseudo-black pattern expressed in the RGB color space, and the synthesized image data is pseudo-cyan, pseudo-magenta, and pseudo-yellow, respectively expressed in the RGB color space as pure primary colors of the three primary colors of cyan, magenta, and yellow. patterns to form pseudo-black, pseudo-cyan, pseudo-magenta and pseudo-yellow patterns without overlapping each other; and synthesizing the pseudo-black, pseudo-cyan, pseudo-magenta and pseudo-yellow patterns. It is characterized by having

A method of generating latent image print data according to the present invention is characterized by arranging pseudo-cyan, pseudo-magenta, pseudo-yellow, and pseudo-black patterns in a matrix or at random.

Further, the method of generating latent image print data of the present invention is characterized in that the gradation of the invisible image and/or the visible image is represented by the image area ratio of the pseudo cyan, pseudo magenta, pseudo yellow and pseudo black patterns. do.

Further, the present invention is characterized by creation software for causing a computer to execute a method of creating latent image print data.

According to the method and software for creating printing data for a latent image print of the present invention, in order to obtain a latent image print of good print quality, the printing of the printer is performed without using a special base material or ink. There are no particular restrictions on control methods, output devices, etc., and latent image prints can be output from a wide variety of printers to obtain prints that require originality and security.

In addition, according to the method and software for creating printing data for latent image printed matter of the present invention, it is not necessary to create data for latent image printed matter specialized for each printer, and one-source multi-use usage is possible. Therefore, it is not necessary for the side to create the data for the latent image printed matter to be troublesome and costly, and the user side does not need to make complicated environment settings for the printer.

4A and 4B are diagrams showing a state of the latent image printed matter observed with the naked eye under normal light and a state of the latent image printed matter observed under infrared light according to the embodiment of the present invention; 4A and 4B are diagrams showing a state of a latent image printed matter observed with the naked eye under normal light and a state of the latent image printed matter observed under infrared light according to another embodiment of the present invention; 1 is a block diagram showing an apparatus for generating latent image print data according to an embodiment of the present invention; FIG. 4 is a flow chart showing a method of creating latent image print data according to an embodiment of the present invention. FIG. 4 shows an example of data conversion in a printer of latent image print data created in the embodiment of the present invention, and a conventional technique; FIG. 4 is a diagram showing data for latent image printed matter created in the embodiment of the present invention and latent image printed matter output from the data by a printer; The figure explaining the Example of this invention. The figure explaining the Example of this invention. FIG. 10 is a view showing an example of data for latent image printed matter according to the prior art and a partially enlarged view thereof;

A mode for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below, and includes various other embodiments within the scope of the technical ideas described in the claims.

(First embodiment)
Regarding the method of creating latent image print data according to the embodiment of the present invention, first, the latent image print (1) to be created will be described with reference to FIGS. 1 and 2. FIG.

(latent image print)
The latent image printed matter (1) is a printed matter printed on the substrate (2), and as shown in FIG. 1(a), the visible image (4) (here gray image), or, as shown in FIG. 2(a), a visible image (4) (characters of "PB" here) is observed with normal naked eyes (T1). On the other hand, with infrared vision (T2) using a camera, optical scanner, etc., as shown in FIGS. 1(b) and 2(b), an invisible image (5) ( In the present embodiment, it is a printed matter in which a face image) is visually recognized.

The images used for the visible image (4) and the invisible image (5) are not limited, and the visible image (4) includes a flat plain image as shown in FIG. Marks, patterns, face images, landscapes, etc. can be applied. Any image such as characters, numbers, symbols, marks, patterns, face images, landscapes, etc. can be applied to the invisible image (5). Both the visible image (4) and the invisible image (5) may be binary images or images having continuous gradation like face images.

(printer)
The latent image printed material (1) to be created is printed by a printer, and the type of printer may be an electrophotographic system, an inkjet system, or a laser printer system, and the system does not matter. In addition to expensive color multifunction machines and digital printers, simple printers for general household use and mobile printers that operate on rechargeable batteries can also be used for printing.

(Base material)
Further, the material of the base material (2) used for the latent image printed material (1) is not particularly limited as long as it has a surface on which the printer can print. Plastics, films, composite substrates obtained by coating paper with films, and the like can be used.

(ink)
The latent image print (1) is printed using four color materials of CMYK that are standard equipment of the printer. At this time, the invisible image (5) is printed with a black (K) toner containing an infrared absorbing pigment or a pigment ink. Images other than the invisible image (5) that are visible with the naked eye are printed with cyan (C), magenta (M), and yellow (Y) toners or pigment inks that do not contain infrared absorbing dyes.

Specifically, the visible image (4) of the latent image printed matter (1) that is visually recognized by ordinary naked eyes shown in FIG. 1A has cyan (C), magenta (M) and yellow (Y) are formed in gray by mixing colors, so that under visible light, an invisible image (5) printed in black (K) containing an infrared absorbing dye and a gray visible image (4) by mixing colors are printed. ) are visually recognized as substantially the same color, the invisible image (5) can be concealed.
Similarly, the visible image (4) of the latent image print (1) shown in FIG. By forming, under visible light, it is possible to hide an invisible image (5) printed with black (K) containing an infrared absorbing dye and form an arbitrary visible image (4).

(Apparatus for creating data for latent image printing (M))
Next, the device (M) for generating latent image print data will be described. FIG. 3 is a block diagram showing the configuration of the latent image print data creation device (M). The latent image print data creation device (M) includes input means (M1), editing means (M2), communication It comprises an interface (M3), a database (M4) and display means (M5).

The input means (M1) has at least invisible image input means (M1a) and, if necessary, visible image input means (M1b). The invisible image input means (M1a) is means for inputting an invisible image (5) that is the basis of the invisible image (5) that is visually recognized when observed under an infrared light source. Also, the visible pattern input means (M1b) is means for inputting a visible image (4) which is the basis of the visible image observed when viewed with the naked eye under normal light. Invisible image (5) and visible image (4) are input by taking pictures with a digital camera, scanning with a scanner, etc., or by reading out arbitrary images recorded in advance in the communication interface (M3) and/or the database (M4). .

The invisible image input means (M1a) or the visible pattern input means (M1b) is composed of a mouse, a keyboard, etc., and uses Photoshop (registered trademark) image processing software commercially available from Adobe (registered trademark). may be used to directly create an invisible image (5) and a visible image (4). Further, the invisible image input means (M1a) or the visible pattern input means (M1b) may input tone curve adjustment values used in the editing means (M2) or input instructions to execute various image processing.

The editing means (M2) shown in FIG. 3 includes at least black and white (monotone) conversion means (M2a), inversion means (M2b), tone curve adjustment means (M2c), pseudo pattern application means (M2d), and synthesis means (M2e). have.

The black and white (monotone) conversion means (M2a) converts the image data input by the invisible pattern input means (M1a) into RGB black and white (monotone) image data (5a).

The reversing means (M2b) performs negative-positive reversal to obtain negative image data (5c) of the black and white (monotone) image data (5a) converted by the black and white (monotone) converting means (M2a).

The tone curve adjusting means (M2c) applies a tone curve to the black and white (monotone) image data (5a) obtained by the black and white (monotone) conversion means (M2a) and the negative image data (5c) obtained by the inverting means (M2b). make adjustments. Further, when the latent image print (1) has a visible image (4) of meaningful information instead of a flat plain image as shown in FIG. Tone curve adjustment is performed on the visible image data (4a).

The pseudo-pattern application means (M2d) applies pseudo-black (iK), pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns to the image data after tone curve adjustment.

The synthesizing means (M2e) synthesizes the pseudo cyan (iC), pseudo magenta (iM), pseudo yellow (iY), and pseudo black (K) patterns obtained by the pseudo pattern applying means (M2b).

The display means (M5) is not particularly limited and may be a personal computer monitor, a dedicated monitor, or the like. Also, the display means (M5) is not an essential component for creating latent image print data.

Note that the output means (P) shown in FIG. 3 is a means for printing the data created by the latent image print data creation device (M) on the substrate (2), and creates the latent image print data. Although it is not an essential configuration, by configuring the output means (P) with a color laser printer, color inkjet printer, etc., and using it in connection with the latent image print data creation device (M), it is possible to It is possible to use one device to create the latent image printed matter (1).

(Method of Creating Data for Latent Image Print)
Next, a method and software for creating latent image print data using the latent image print data creating apparatus (M) described above will be described with reference to FIG. Note that the processing flow shown in FIG. 4 will be described together with images after processing in order to make the process of processing easier to understand.

The method of generating latent image print data includes at least a main processing flow (F1) surrounded by a solid line in FIG. 4, and further includes a sub-processing flow (F2) surrounded by a dotted line in FIG. 4 if necessary. there is In the case of only the main processing flow (F1) in FIG. 4, a flat gray image is observed with normal naked eyes as shown in FIG. 1(a), but when observed under an infrared light source (T2), As shown in (b), a latent image print (1) is obtained in which an invisible image (5) that was not visually recognized with the naked eye (T1) is visually recognized. Further, when both the main processing flow (F1) and the sub-processing flow (F2) in FIG. 4 are provided, as shown in FIG. 4) is visually recognized, and in the infrared vision (T2), the latent image printed matter (1) in which the invisible image (5) that was not visually recognized with the normal naked eye (T1) as shown in FIG. can get.

(Main processing flow (F1))
First, the main processing flow (F1) surrounded by the solid line in FIG. 4 will be described.

(Step 1 Invisible image specification/black-and-white conversion)
In Step 1 shown in FIG. 4, the invisible image input means (M1a) of the latent image print data creation device (M) designates the first image data (5a) as the base image of the invisible image (5). In this embodiment, an image such as a face image having continuous gradation, which is the original image of the invisible image (5), is input from the communication interface (M3) or the database (M4). At this time, RGB image data is used as the input source. In this embodiment, the invisible image (5) is a face image having continuous gradation, but the type of image is not limited at all.

Invisible image (5) is an image printed by a printer with black (K) toner containing infrared absorbing pigment or pigment ink, so it is a monotone (black and white) expression in which all 256 gradations of each RGB channel are the same. do. Therefore, when the image input from the invisible image input means (M1a) is 24-bit RGB image data in color representation, it is converted to black and white (monotone) by the black and white (monotone) conversion means (M2a) of the editing means (M2). Processing is applied to obtain black and white (monotone) RGB image data (5a'). In addition, if the image input from the invisible image input means (M1a) is an 8-bit grayscale image, or if it is a 32-bit CMYK image, a process for converting it to a monotone 24-bit RGB image is separately added, and black and white (monotone) RGB Image data (5a') is obtained. If the image input from the invisible image input means (M1a) is monotone (black and white), this conversion can be omitted. The above is Step 1.

(Step 2 negative-positive inversion)
Next, in Step 2, negative image data (5c) is obtained by inverting the monochrome (monotone) RGB image data (5a') obtained in Step 1. FIG. That is, the invisible image data (5a) and the negative image data (5c) of the invisible image data have a negative/positive relationship. In this embodiment, since the black-and-white (monotone) RGB image data (5a') has continuous gradation, the inverted invisible image data (5c) also has continuous gradation.

(Step 3 Adjustment of tone curve)
In Step 3, first, the tone curve of black and white (monotone) RGB image data (5a') is adjusted to obtain black and white (monotone) RGB image data (5b) after tone curve adjustment. The black-and-white (monotone) RGB image data (5b) after the tone curve adjustment becomes an image printed in black (K) containing an infrared absorbing dye in a printer. Subsequently, in Step 3, the tone curve of the negative image data (5c) is further adjusted to obtain negative image data (5d) after tone curve adjustment. The negative image data (5d) after the tone curve adjustment becomes an image printed in cyan (C), magenta (M) and yellow (Y) that does not contain an infrared absorbing dye by a printer.

Here, the tone curve adjustment in Step 3 will be described. In the tone curve adjustment, when the black and white (monotone) RGB image data (5b) after the tone curve adjustment and the negative image data (5d) after the tone curve adjustment are combined in a negative/positive manner, a uniform flat density is obtained. cyan (C), magenta (M), yellow (Y) and black (K). At that time, the four types of patterns of cyan (C), magenta (M), yellow (Y) and black (K) should not overlap each other, that is, halftone dots printed by the printer should not overlap each other. In order to achieve this, it is necessary to set the image line area ratio of each pattern to 25% or less. To achieve this configuration, the tone curve applied to the RGB image is adjusted to a range of about 0% to 25% image line area ratio (range of 191 to 255 for the RGB image). As shown in FIG. 4, black and white (monotone) RGB image data (5b) and negative image data (5d) after tone curve adjustment are black and white (monotone) RGB image data (5a′) and before tone curve adjustment. Compared with the negative image data (5c), the image data is pale black and white (monotone).

The tone curve can be adjusted, for example, by setting a predetermined tone curve using the tone curve changing function of Photoshop (registered trademark), which is commercially available image processing software manufactured by Adobe (registered trademark). Also, the tone curve can be adjusted according to the characteristics of the printer used for printing. The above is the description of Step 3.

(Step 4 Application of pseudo pattern)
In Step 4, a pseudo pattern is applied to the black and white (monotone) RGB image data (5b) after tone curve adjustment and the negative image data (5d) after tone curve adjustment. In Step 4, first, a pseudo black (iK) pattern is applied to the black and white (monotone) RGB image data (5b) after tone curve adjustment. Next, pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns are applied to the negative image data (5d) after tone curve adjustment.

Here, pseudo black (iK), pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY) in Step 4 will be explained. Pseudo-black (iK), pseudo-cyan (iC), pseudo-magenta (iM) and pseudo-yellow (iY) are the pure primary colors of CMYK printing: black (K), cyan (C), magenta (M) and yellow ( Y) is expressed in the RGB color space.

The RGB color space is a color space that is represented by the three primary colors of red, green, and blue light, and each color of RGB is represented by a combination of numerical values from 0 to 255. Note that the values of RGB are not absolute values, but values relative to the width of the color gamut. In this embodiment, as an example, the pure primary color (100% color) of cyan (C) in the CMYK printing color is represented by R0, G159, and B230 as pseudo cyan (iC) in the RGB color space. Also, the pure primary color (100% color) of magenta (M) is represented by R194, G0, and B123 as pseudo magenta (iM). Similarly, the pure primary color (100% color) of yellow (Y) is represented by R255, G240, and B0 as pseudo yellow (iY). Also, the pure primary colors of black (K) are represented by R0, G0, and B0.

In the above description, pseudo cyan (iC) is represented by R0, G159, and B230, but pseudo cyan (iC) can also be represented by a combination of different numerical values such as R0, G255, and B255. Similarly, pseudo magenta (iM) can be represented by a combination of R255, G0 and B255, and pseudo yellow (iY) can be represented by a combination of R255, G255 and B0. In other words, pseudo-black (iK), pseudo-cyan (iC), pseudo-magenta (iM) and pseudo-yellow (iY) are generally CMYK printing colors of cyan (C), magenta (M), yellow (Y) and black (K). ) must be expressed as

Here, the effect of the above configuration will be described in comparison with the conventional technology. FIGS. 5A and 5B are diagrams showing an example of data conversion when latent image print data is output by an output device. FIG. 5A explains the present invention, and FIG. 5B explains the prior art. be.
The prior art pattern of FIG. 5(b) consists of cyan (C), magenta (M), yellow (Y) and black (K), whereas the pattern of the present invention shown in FIG. 5(a). The pseudo pattern is composed of pseudo cyan (iC), pseudo magenta (iM), pseudo yellow (iY) and pseudo black (iK) patterns.

As shown in FIG. 5B, in the prior art, when the input source is a CMYK image (e1), it is converted to an RGB image (e2) by the printer driver, and a dedicated color profile optimized for the output device is applied. , is converted into a CMYK image (e3) again by the printer driver and printed. At that time, when cyan (C), magenta (M), yellow (Y), and black (K) of the CMYK image (e1) are converted to the RGB image (e2), pseudo cyan ( iC), pseudo-magenta (iM), pseudo-yellow (iY), and pseudo-black (iK), and black is expressed by mixing dots and lines of cyan (C), magenta (M), and yellow (Y). The resulting color component becomes pseudo black (iK).

Furthermore, when the RGB image (e2) is converted back to the CMYK image (e3), depending on the dedicated color profile, the pseudo black (iK) may be converted to a color component consisting mainly of black (K) or black (K) only. Replaced by color components containing small amounts of cyan (C), magenta (M) and yellow (Y). Since this dedicated color profile cannot be rewritten by the user, it is difficult to print latent image print data such as shown in FIGS. 1 and 2 with an inexpensive home printer.

In the present invention, as shown in FIG. 5(a), since the input source is RGB image data (d1), when outputting with a printer, CMYK image data (d2) is processed by the printer driver via a dedicated color profile. However, as described above, pseudo-cyan (iC), pseudo-magenta (iM), pseudo-yellow (iY), and pseudo-black (iK) provided in the RGB image data (d1) before conversion are generally cyan (C), magenta (M), yellow (Y), and black (K), the input source RGB image data (d1) and the converted CMYK image data (d2) have the same color configuration. . As described above, in the present invention, since there are no restrictions on the printer driver, dedicated color profile, etc., it is possible to reproduce the colors of the latent image data for printed matter as they are in the printed matter.

(Pseudo pattern shape and placement)
Next, in Step 4, the pattern shape and arrangement when applying pseudo cyan (iC), pseudo magenta (iM), pseudo yellow (iY), and pseudo black (iK) will be described. First, as shown in FIG. 4, a pseudo-black (K) pattern (5e) is arranged on the black and white (monotone) RGB image (5b) after tone curve adjustment obtained in Step 3. Similarly, in Step 4, each pattern (5f) of pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY) is applied to the negative image data (5d) after tone curve adjustment obtained in Step 3. Place like At this time, as shown in FIG. 4, the pseudo-black (iK) pattern (5e) and the pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns (5f) are arranged so as not to overlap each other. be done.

In this embodiment, the pseudo black (iK) pattern is arranged by dots. For example, when the image resolution of the black and white (monotone) RGB image data (5a) before tone curve adjustment is 600 dpi, the dot size is 336 μm, which corresponds to 75 lines/inch in printed matter. In an image of 32 horizontal pixels and 16 vertical pixels, a pseudo black (iK) pattern is arranged as dots, and a pseudo black (iK) pattern is arranged according to the continuous gradation of the black and white (monotone) RGB image data (5b) after tone curve adjustment. A black (iK) pattern of dots is placed.

Also, the pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY) patterns (5f) are similarly arranged in dots. For example, in the present embodiment, each of pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY) is composed of dots consisting of connected components of 8×8 pixels, and a negative image after tone curve adjustment is obtained. Place dots of pseudo-cyan (iC), pseudo-magenta (iM) and pseudo-yellow (iY) patterns according to the continuous tone of data (5d).

Note that the size of the dots can be changed as appropriate for each of the pseudo-black (iK) pattern, pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns. In addition, the size of the dots can be increased by connecting dots to increase the image line area ratio, so that the invisible image (5) can be expressed in continuous gradation. In the present invention, the image area ratio refers to the ratio of dots, pixels, or image lines per unit area.

In this embodiment, the pseudo patterns are formed of dots, but each pseudo pattern may be dots as shown in FIG. 4 or pixels as shown in FIG. It may also be a streak (not shown) or a combination thereof. Further, as described above, in order to express continuous gradation, the size of the elements forming the pseudo-pattern can be changed by connecting dots or connecting pixels. Furthermore, the pseudo patterns are formed in the order of pseudo cyan (iC), pseudo magenta (iM), pseudo yellow (iY), and pseudo black (iK) from the left in FIG. It can be random. Also, like the printed pattern portion (2a) shown in FIG. 9 of the prior art, the visible image area (a) and the invisible image area (b) may be arranged in a matrix with desired positional relationships. I do not care. Furthermore, the shapes of the pseudo-patterns may be randomly arranged instead of regularly arranged in a matrix.

In the present invention, a "dot" is a printing halftone dot itself or a pixel itself, which is the minimum unit forming a printed pattern, or a mass of image element formed by gathering a plurality of printing halftone dots or pixels. , polygons including circles, triangles, and quadrilaterals. "Image line" means an image element formed by continuously arranging printing halftone dots or pixels, which are the minimum units for forming a printing pattern, in a specific direction. , curves and wavy lines. In the embodiment of the present invention, when the dots, pixels, or image lines are finally combined in Step 5, they should be arranged so as not to overlap each other.

As will be described later, the pseudo-black (iK) pattern (5e) and the pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns (5f) are synthesized in step 5. In the combined image data (5g), pseudo cyan (iC) and pseudo magenta are added as necessary so that the invisible image (5) composed of the pseudo black (iK) pattern (5e) is not visually recognized. (iM) and pseudo-yellow (iY) patterns (5f) are adjusted to the desired color balance.

(Step 5 Pseudo-pattern synthesis)
Synthesis of pseudo patterns in Step 5 will now be described. In Step 5, the pseudo-black (K) pattern (5e) obtained in Step 4 is combined with the pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns (5f) to obtain synthesized image data ( 5g). In other words, in the pseudo-pattern synthesis of Step 5, pseudo-black (iK) dot groups and pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) dot groups are synthesized as RGB image data. The composite image data (5g) is image data printed with cyan (C), magenta (M), yellow (Y) and black (K) toners or pigment inks in a printer.

A latent image print (1) obtained by printing the synthetic image data (5g) obtained in Step 5 with a printer is pseudo cyan (iC), pseudo magenta (iM), pseudo yellow (iM) shown in the synthetic image data (5 g) in FIG. Cyan (C), magenta, (M) yellow (Y), and black (K) reflect the size and positional relationship of dots composed of (iY) and pseudo black (iK). When this latent image print (1) is viewed with the naked eye under normal light, a flat gray visible image (4) as shown in FIG. 1(a) is observed. , an invisible image (5) that was not visually recognized with the naked eye (T1) as shown in FIG. 1(b) is visually recognized. The above is the main processing flow (F1) surrounded by the solid line in FIG.

Next, description will be made based on the sub-processing flow (F2) enclosed by the dotted line in FIG.

(Step 6 Designation of visible image)
In Step 6 shown in FIG. 4, the visible image input means (M1b) of the latent image print data generating device (M) designates the second image data (4a) as the base image of the visible image (4). In this embodiment, visible image data (4a), which is the original of the visible image (4), is input from the communication interface (M3) or database (M4). At this time, as in Step 1, 24-bit RGB image data is used as the input source. In this embodiment, the visible image data (4a) is described using alphabetic characters as an example, but the type of image is not limited at all.

In this embodiment, the visible image data (4a) is a 24-bit RGB image, but if the image input from the visible image input means (M1b) is an 8-bit grayscale image or a 32-bit CMYK image, it is converted to a 24-bit RGB image. Add a separate process to

(Step 7 Adjustment of tone curve)
Next, in Step 7, the tone curve of the visible image data (4a) obtained in Step 6 is adjusted to obtain RGB image data (4b) of the visible image after tone curve adjustment. The tone curve in step 7 can be adjusted arbitrarily. In this embodiment, the maximum densities of cyan (C), magenta (M), and yellow (Y) after printing the tone curve do not exceed 50% each. adjusted to The RGB image data (4b) of the visible image after tone curve adjustment is an image printed in cyan (C), magenta (M), and yellow (Y) that does not contain infrared absorbing dyes by the printer.

(Step 8 Synthesis of images)
Next, in step 8, image synthesis is performed by multiplying each RGB image data of the visible image data (4b) after tone curve adjustment and the negative image data (5d) after tone curve adjustment to synthesize the tone curve. Synthetic image data (6) after curve adjustment is obtained. The synthesized image data (6) after tone curve adjustment is an image printed in cyan (C), magenta (M), and yellow (Y) after printing. The above is the sub-processing flow (F2) surrounded by the dotted line in FIG.

In this embodiment, pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns are applied to synthesized image data (6) after tone curve adjustment obtained by synthesizing the images in Step 8. is composed of dots consisting of connected components of 8×8 pixels, and is formed so that the connected components of each pixel increase or decrease according to the continuous gradation of synthesized image data (6) after tone curve adjustment. In this way, the size of the dots can be changed as appropriate for each of the pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns. It can be expressed in gradation. The application of the pseudo CMY pattern to the synthesized image data (6) obtained after the tone curve adjustment is the same as the application of the pseudo CMY pattern in Step 4 described above, so the explanation is omitted.

Image data (5g') obtained in Step 5 is shown in FIG. FIG. 6A shows the image data (5g') obtained in Step 5 and its enlarged view. As shown in FIGS. 4 and 6(a), the image data (5g') is composed of pseudo-cyan (iC), pseudo-magenta (iM), pseudo-yellow (iY), and pseudo-black (iK) dots. They are arranged so that they do not overlap. FIG. 6(b) is a latent image print (1) obtained by printing out the image data (5g') and its enlarged view. The latent image print (1) is formed of cyan (C), magenta, (M) yellow (Y), and black (K) color materials that directly reflect the size and positional relationship of the dots in the image (5g′). ing.

When this latent image print (1) is viewed with the naked eye under normal light, a visible image (4) as shown in FIG. 2(a) is observed. An invisible image (5) that was not visually recognized with the naked eye (T1) as shown in (1) is visually recognized.

(software)
The present invention also provides creation software for causing a computer to execute a method of creating latent image print data.

Although an embodiment of the invention has been described, this embodiment is presented as an example and is not intended to limit the technical scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. This embodiment and its modifications are included in the technical scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

(Example 1)
A latent image print (1) shown in FIG. 2 was created according to the flow shown in FIG. 4 using the latent image print data creating apparatus (M) shown in FIG.

In Step 1, the invisible image input means (M1a) inputs 24-bit RGB image data (5a) with a resolution of 600 dpi as the first image data, and converts it to black and white (monotone) by the black and white (monotone) conversion means (M2a) of the editing means (M2). Monotone) conversion processing was added to obtain black and white (monotone) RGB image data (5a′). In Step 6, 24-bit RGB image data (alphabet "PB") with a resolution of 600 dpi was input as second image data in the visible image input means (M1b) to obtain visible image data (4a).

In Step 2, the black and white (monotone) RGB image data (5a') obtained in Step 1 is inverted to create negative image data (5c) of the face image.

In Step 3, the tone curve of the black and white (monotone) RGB image data (5a') is adjusted to obtain the black and white (monotone) RGB image data (5b) after the tone curve adjustment. Further, the tone curve of the negative image data (5c) was adjusted to obtain the negative image data (5d) after tone curve adjustment.

Further, in Step 7, the tone curve of the input visible image data (4a) was adjusted to create visible image data (4b) after tone curve adjustment.

In Step 8, each RGB image data of the visible image data after tone curve adjustment (4b) and the negative image data after tone curve adjustment (5d) are synthesized by multiplication to create synthesized image data after tone curve adjustment (6). did.

Next, in Step 4, a pseudo-black (K) pattern (5e) is arranged by dots on the black and white (monotone) RGB image (5b) after the tone curve adjustment obtained in Step 3. In addition, each pattern (5f) of pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY) is arranged by dots on the combined image data (6) after tone curve adjustment obtained in Step 8. did. At this time, as shown in FIG. 4, the dots of the pseudo black (iK) pattern (5e) and the pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY) patterns (5f) are are arranged so that they do not overlap each other.

In Step 5, the pseudo-black (K) pattern (5e) obtained in Step 4 is combined with the pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns (5f) to generate synthesized image data ( 5g).

Synthetic image data (5g) obtained in Step 5 is output means (P), using Ricoh (registered trademark) laser printer SP-740 with a resolution of 600 dpi, cyan (C), magenta ( M), yellow (Y), and black (K) toners on white color copier paper (Ncolor 081, manufactured by Fuji Xerox Co., Ltd.).

When the latent image print (1) thus prepared was observed with the naked eye under normal light, the alphabet "PB" shown in FIG. 2(a) was visible. Further, when this latent image print (1) is observed using an infrared camera, as shown in FIG. was visible.

Thus, according to the present invention, a latent image print (1) having a desired density and hue can be obtained from a wide variety of printers without any particular restrictions on the printer's print control method, output device, or the like. As a result, it is not necessary for the side to create the data for the latent image printout to spend time and money, and the user side does not need to make complicated environment settings for the printer.

(Example 2)
Example 2, as shown in FIG. 7, is an example of a certificate of disaster that needs to be issued in the event of a disaster. Image data for the latent image print (1), which is a logo mark (alphabet "PB") and an invisible image (5) that can be observed with an infrared camera, is a face image of the individual requesting the issuance of a disaster victim certificate. This is a creation example. In the second embodiment, the smartphone is the latent image print data creation device (M) shown in FIG. 3, and has the processing flow of FIG. In other words, latent image print data is created using a dedicated application in which the software of the present invention is installed on a smartphone. In addition, in Example 2, Step 1, Step 4, and Step 6 will be explained, and since the other steps are the same as those in Example 1, the explanation will be omitted.

In Step 1, the first image data input from the invisible image input means (M1a) is the face image of the individual requesting the issuance of the disaster certificate. ) was converted to black and white (monotone) using the function provided in the smartphone as black and white (monotone) conversion means (M2a) of ), and black and white (monotone) RGB image data (5a) with a resolution of 600 dpi was obtained. In Step 6, as the second image data in the visible image input means (M1b), 24-bit RGB image data with a resolution of 600 dpi, which is the logo mark (alphabet "PB") of the local government issuing the disaster certificate, is input, Visible image data (4a) were obtained.

In Step 4, a pseudo-black (K) pattern (5e) is arranged by pixels in the black and white (monotone) RGB image (5b) obtained in Step 3 after tone curve adjustment. In addition, each pattern (5f) of pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY) is arranged by pixels for the synthesized image data (6) after tone curve adjustment obtained in Step 8. did. At this time, as shown in FIG. 4, the pixels of the pseudo-black (iK) pattern (5e) and the pseudo-cyan (iC), pseudo-magenta (iM), and yellow (iY) patterns (5f) are combined into They were arranged so that they would not overlap each other.

In addition, the color balance of the pseudo-cyan (iC), pseudo-magenta (iM), and pseudo-yellow (iY) patterns was adjusted so that the invisible image (5) composed of the pseudo-black (iK) pattern was not visually recognized. .

In addition, as shown in the upper part of FIG. 8, the pseudo patterns are arranged in a grainy pattern by pixels of pseudo black (iK), pseudo cyan (iC), pseudo magenta (iM), and pseudo yellow (iY). formed by random arrangement.

The synthesized image data (5g) obtained in Step 5 is wirelessly transmitted from the smartphone to the mobile printer PIXUS (registered trademark) iP110 manufactured by Canon (registered trademark), which is the output means (P), and black (K), cyan ( C), magenta (M) and yellow (Y) inks were used for printing on white color copy paper (Ncolor 081, manufactured by Fuji Xerox Co., Ltd.).

In this way, the present invention can be used not only for the prompt issuance of certificates of disaster victims when networks cannot be used in the event of a disaster such as an earthquake, but also for the simple issuance of certificates that require originality and security. .

Further, if a grainy pixel array such as error diffusion dither is used as in the second embodiment, when the resolution of the output device is 600 dpi, the latent image printed matter (1) has an image resolution equivalent to 600 dpi. A visible image (4) and an invisible image (5) can be formed. In other words, it can be expressed with the maximum image resolution of the output device. As a result, the image resolution can be increased to the pixel unit of the set image resolution even in a simple inexpensive home-use printer or a mobile printer that operates on a rechargeable battery.

Further, in Example 2, the pseudo cyan (iC), pseudo magenta (iM), pseudo yellow (iY), and pseudo black (iK) patterns are randomly arranged with grainy pixels, and there is a degree of freedom. Any design such as characters and figures can be provided with details that can be expressed by the maximum image resolution of the device.

1 Latent image printed matter 2 Base material 3 Infrared camera 4 Visible image 4a Second image data 4b RGB image data of visible image after tone curve adjustment 5 Invisible image 5a First image data 5a' Black and white (monotone) RGB image data 5b Black and white (monotone) RGB image data after tone curve adjustment 5c Negative image data 5d Negative image data after tone curve adjustment 5e Pseudo black (K) pattern 5f Pseudo cyan (iC), pseudo magenta (iM), pseudo yellow ( Each pattern 5g of iY) Synthetic image data 6 Synthetic image data after tone curve adjustment M Latent image print data creation device M1 Input means M1a Invisible image input means M1b Visible image input means M2 Editing means M2a Black and white (monotone conversion means)
M2b Inversion means M2c Tone curve adjustment means M2d Pseudo pattern application means M2e Synthesis means M3 Communication interface M4 Database M5 Display means P Output means F1 Main processing flow F2 Sub-processing flow T1 Ordinary naked eye vision T2 Infrared vision

Claims (6)

A method for creating printing data for a latent image printed matter in which an invisible image is visually recognized under infrared light,
obtaining first image data as a base image of the invisible image to obtain black and white (monotone) RGB image data;
inverting the black and white (monotone) RGB image data to obtain negative image data;
adjusting tone curves of the black and white (monotone) RGB image data and the negative image data;
The black and white (monotone) RGB image data after tone curve adjustment is formed by a pseudo-black pattern expressed in an RGB color space, and the negative image data is converted into the three primary colors of cyan, magenta, and yellow as pure primary colors in the RGB color space. and forming the pseudo-cyan, pseudo-magenta, and pseudo-yellow patterns respectively represented by , and forming the pseudo-black, the pseudo-cyan, the pseudo-magenta, and the pseudo-yellow patterns without overlapping each other;
combining the pseudo-black, pseudo-cyan, pseudo-magenta and pseudo-yellow patterns;
A method for creating latent image print data, comprising: 2. The method of generating latent image print data according to claim 1, wherein the gradation of the invisible image is represented by the image line area ratios of the pseudo cyan, the pseudo magenta, the pseudo yellow and the pseudo black patterns. . A method for creating printing data for a latent image printed matter in which a visible image is visible with the naked eye under normal light and an invisible image is visible under infrared light,
obtaining first image data as a base image of the invisible image to obtain black and white (monotone) RGB image data;
inverting the black and white (monotone) RGB image data to obtain negative image data;
adjusting tone curves of the black and white (monotone) RGB image data and the negative image data;
obtaining second image data as a base image of the visible image to obtain RGB image data of the visible image;
adjusting a tone curve of RGB image data of the visible image;
a step of synthesizing the RGB image data of the visible image after tone curve adjustment with the negative image data after tone curve adjustment to obtain synthesized image data;
The black and white (monotone) RGB image data after the tone curve adjustment is formed by a pseudo-black pattern expressed in an RGB color space, and the synthesized image data is converted into pure primary colors of cyan, magenta, and yellow in the RGB color space. and forming the pseudo-cyan, pseudo-magenta, and pseudo-yellow patterns respectively represented by , and forming the pseudo-black, the pseudo-cyan, the pseudo-magenta, and the pseudo-yellow patterns without overlapping each other;
combining the pseudo-black, pseudo-cyan, pseudo-magenta and pseudo-yellow patterns;
A method for creating latent image print data, comprising: 4. The latent image printing material according to claim 1, wherein the pseudo cyan, pseudo magenta, pseudo yellow, and pseudo black patterns are arranged in a matrix or at random. How the data was created. 5. The gradation of the invisible image and/or the visible image is represented by the image line area ratio of the pseudo cyan, the pseudo magenta, the pseudo yellow and the pseudo black pattern. A method for creating data for latent image printing as described. Creation software for causing a computer to execute the latent image print data creation method according to any one of claims 1 to 5.

Images