JP5920783B2 - Method for producing halftone print - Google Patents

Description

  The present invention relates to a method for producing halftone prints that require anti-counterfeiting and falsification prevention functions such as banknotes, passports, securities, cards, and valuable prints.

  In recent years, with the increase in image quality and functionality of color copiers, counterfeit printed products such as banknotes and securities have become a serious problem. For this reason, conventionally, an image having a halftone dot configuration that is difficult to be copied by a copying machine has been often used for valuable printed matter.

  As a halftone dot configuration that is difficult to duplicate, for example, there is one related to Patent Document 1 filed earlier by the present applicant. This is because two different images are embedded by arranging two different halftone areas equally on the same plane and arranging a halftone dot representing one continuous tone image for each halftone area. Halftone dot print.

  This halftone printed matter will be described with reference to FIG. The halftone dot printed matter (1) shown in FIG. 1 (a) has a plurality of second halftone areas on the surface of the substrate (2) as shown in the enlarged view of FIG. 1 (b). 1 halftone region (3) and a plurality of second halftone regions (4).

  As shown in FIG. 1C, in the first halftone region (3), a visible image (5) visible under a normal light source is formed by arranging the first halftone portion (3a). Is done. The first halftone dot portion (3a) is formed of cyan (C), magenta (M) and yellow (Y) used in general commercial printing.

  In addition, as shown in FIG. 1D, in the second halftone region (4), a second halftone dot portion (4a) representing the latent image (6) when observed under an infrared light source. Is formed with black (K) used in general commercial printing, and the second background portion (4b) is black in which the colors of cyan (C), magenta (M) and yellow (Y) are superimposed. (Hereinafter referred to as “mixed color black”).

  Cyan (C), magenta (M), and yellow (Y) have characteristics that do not absorb infrared rays. On the other hand, black (K) used in general commercial printing has a characteristic of absorbing infrared rays because it is mainly composed of carbon black. As a result, the second halftone area (4) under the normal light source is visually recognized in black because the second halftone area (4a) and the second background area (4b) are black. The net state is reached, and the visible image (5) is visually recognized. On the other hand, only the second halftone dot portion (4a) that forms the latent image is visible under the infrared light source. Therefore, the latent image (6) composed of the plurality of second halftone dots (4a) is visually recognized.

  When producing the halftone print (1) of Patent Document 1 described above, there are two production methods. One method is a method of printing continuously in large quantities using an offset printer. In this case, black (K) that is a latent image and cyan (C), magenta (M), and yellow (Y) that are gradation images are respectively black (K) by the halftone dot arrangement shown in FIG. ) Ink, cyan (C) ink, magenta (M) ink, and yellow (Y) process ink are substituted to create plate-making data for each color, and the four printing plates are printed based on the plate-making data. Since the desired halftone dot printed matter can be easily produced by printing after the production, there is no particular difficulty.

  On the other hand, in addition to the method of printing with an offset printing machine, a production method using a printer has been demanded as a method for easily producing a halftone dot printed matter of Patent Document 1 without using a printing plate. However, in the production method of an offset printing machine, it was possible to produce plate making data for each color separately, but when outputting using a printer, it was necessary to produce each color as one image data. . Therefore, in order to make it possible to easily output the halftone dot printed matter of Patent Literature 1 using a printer, in Patent Literature 2 previously disclosed by the present applicant, the halftone dot of Patent Literature 1 using a printer is disclosed. A method for producing a printed material is disclosed.

  The special halftone dot composition proposed in Patent Document 1 described above is easily produced by the method for producing a halftone dot print disclosed in Patent Document 2 previously filed by the present applicant, and output in a desired state. It became possible to obtain as a thing.

  FIG. 2 is a flowchart showing a method for producing a halftone print in Patent Document 2. First, the first original image that is the basis of the visible image is input to the image processing unit, and the size of the area of a single color halftone dot, the presence or absence of a halftone dot, the distribution density of a single color pixel, or a pixel having gradation information A first image expressed by is generated (STEP 1).

  Next, a gray image having the same image width and image height as the first image is created, and this gray image is input to the image processing unit (STEP 1 ′) and converted by the mask image creating unit, Obtain (STEP2).

  Next, the second original image, which is the basis of the latent image, is input to the image processing unit so as to have the same image width, image height, and image resolution as the first image, and the area in a single color halftone dot A second image that is recognized only under a specific observation condition is produced by the distribution density of the large or small or single color pixels (STEP 1 ″).

  Next, the mask image and the second image are input to the mask processing unit, and mask processing is performed (STEP 3). This corresponds to the first halftone region (3) in the second image by performing processing for replacing all the portions corresponding to the white pixels of the mask image with white pixels on the second image. All parts are replaced with white.

  The mask image obtained in STEP 2 is overlaid on the first image input in STEP 1, and further, the second image after mask processing obtained in STEP 3 is overlaid thereon to synthesize all the images. (STEP4).

  The image data created through the above steps includes two pieces of image information: a first image created based on a visible image and a second image created based on a latent image. Therefore, based on this image data, it is possible to output by a printer.

  However, when the printed material of Patent Document 1 is manufactured by the manufacturing method of Patent Document 2, a desired print image, and further, the latent image image of the above-described latent image printed material are controlled by various printer manufacturers' own control methods. There was a problem that it was not possible to print properly.

  FIG. 3 is a schematic diagram when the halftone dot printed material of Patent Document 1 manufactured by the manufacturing method of Patent Document 2 is observed under a normal light source. In the halftone dot printed matter (1) shown in Patent Document 1, the second halftone dot portion (4a) is formed of black (K) and the second background portion (4b) is formed of mixed color black. The printer received image data to be output in red (R), green (G), and blue (B) instead of cyan (C), magenta (M), yellow (Y), and black (K). After that, the mechanism is such that the dark color of the image data is automatically output in black (K) and the bright color is output in cyan (C), magenta (M) and yellow (Y).

  In other words, even when image data is created only with cyan (C), magenta (M), and yellow (Y), when output using a general printer, if there is a dark spot in the image data, it is automatically performed. The output is replaced with black (K) ink. Conversely, even when image data is created using only black (K), if there is a bright spot in the image data, it is automatically replaced with cyan (C), magenta (M), and yellow (Y) ink. Output.

  Therefore, in order to make the second halftone dot portion (4a) and the second background portion (4b) both visually visible under a normal light source, the second halftone dot portion (4a) and the second background portion ( When image data is produced so that all of 4b) are output in black, in a general printer, the second background portion (4b) is determined as a dark color, and cyan (C), magenta (M), and In spite of wanting to output only yellow (Y), cyan (C), magenta (M) and yellow (Y) are automatically mixed with black (K) and output.

  As a result, the second halftone dot portion (4a) and the second background portion (4b) are both visually recognized under the infrared light source, and there is a problem that the visibility of the latent image is lowered.

  In this problem, as shown in FIG. 3B, the halftone dot configuration disclosed in Patent Document 1 is the same as that disclosed in Patent Document 3 previously disclosed by the present applicant so that output can be performed in any printer. After the second halftone area (4) is divided into four, each of the four primary colors of cyan (C), magenta (M), yellow (Y) and black (K) is divided into each divided area. A halftone dot configuration is proposed without overlapping. Therefore, by producing the halftone printed matter of Patent Document 1 using the halftone dot structure of Patent Document 3 by the production method of Patent Document 2, any printer outputs a mixture of black (K) and black (K). This makes it possible to express a latent image.

Japanese Patent No. 3544536 JP 2009-202420 A Japanese Patent No. 4214262

  However, in order to prevent replacement of ink, which is a problem of general printers, using the halftone dot configuration of Patent Document 3, known output devices such as general printers, offset printers and gravure printers are known. The second half formed by dividing the ink with four different colors of cyan (C), magenta (M), yellow (Y), and black (K) under a normal light source. In order to form the tone area (4) so as to be visible as uniform black, and to make all the plurality of second halftone areas (4) visible as uniform colors, cyan (C), Color adjustment of magenta (M), yellow (Y) and black (K) is very difficult.

  Therefore, the second halftone region (4) is not visually recognized as uniform black under a normal light source, and the latent image (6) may be slightly visually recognized as shown in FIG. 3 (c). .

  The present invention has been made to solve the above-mentioned problems, and the second type formed of black (K) even when a known printing machine such as an output machine such as a general printer or an offset printing machine is used. This is a method for producing a halftone dot printed material in which the halftone dot portion (4a) and the second background portion (4b) formed of mixed color black are visible as a uniform color under a normal light source. Furthermore, it is an object of the present invention to provide a method for producing a halftone printed matter in which a latent image is not visually recognized under a normal light source as compared to the conventional case, and the visibility of the latent image is favorable under an infrared light source.

  In order to achieve the above-described object, according to the first aspect of the present invention, a plurality of first halftone regions and second halftone regions are arranged on a substrate so that at least the first halftone region and the second halftone region are adjacent to each other. The tone region has a first halftone dot portion that forms a visible image with the first color material, and the second halftone region includes a second halftone dot portion that forms a latent image and a second background. The second halftone dot portion is formed of a second color material having a first functionality that is visible under a predetermined observation condition, and the second background portion is a first functionality. Or a halftone dot printed material formed of a third color material having a second functionality different from the first functionality, and an original image of a visible image comprising a plurality of pixels First image data and second image data which is an original image of a latent image composed of a plurality of pixels. In order to prevent the latent image from being visually recognized in the visible image under the conditions other than the predetermined observation condition and the obtaining step, the brightness of the first image data is used as a process for correcting the first image data. Subtracting the brightness of the second image data to create brightness composite data, the position, shape and dimensions of each of the plurality of second halftone areas, and the second halftone area included in each second halftone area Obtaining or producing mask data relating to the positions, shapes, and dimensions of the two halftone dot portions and the second background portion; and second image data, image data formed by a plurality of second halftone regions; Therefore, after superimposing the second image data and the mask data, a mask process for replacing all the portions corresponding to the white pixels of the mask data in the second image data with white pixels. A step of synthesizing the mask data, the second image data after the mask processing, and the lightness synthesis data, creating a synthesis data, and outputting the synthesis data to the substrate by a predetermined method. It is a method for producing a halftone print.

  According to a second aspect of the present invention, in the method for producing a halftone dot printed matter according to the first aspect, the step of creating the lightness composite data includes the highest lightness in the plurality of pixels constituting the second image data. The highest brightness in the plurality of pixels constituting one image data is replaced with the lowest brightness in the plurality of pixels constituting the second image data to the lowest brightness in the plurality of pixels constituting the first image data. And a step of creating lightness adjustment data, and a step of adding the lightness of the lightness adjustment data to the lightness of the first image data to create lightness composite data.

  According to a third aspect of the present invention, in the method for producing a halftone printed matter according to the second aspect, the step of creating the brightness adjustment data includes a step of extracting brightness information from the second image data, and a second image. A step of compressing the brightness of the second image data by reducing a difference in brightness between a pixel having the highest brightness and a pixel having the lowest brightness among the plurality of pixels constituting the data. Features.

  Furthermore, the invention described in claim 4 is the method for producing a halftone dot printed material according to claim 3, wherein the color material forming the second halftone dot portion has a lightness higher than that of the color material forming the second background portion. If it is low, the brightness of the plurality of pixels constituting the first image data is set higher than the brightness of the plurality of pixels constituting the second image data between the step of extracting the brightness information and the step of compressing the brightness. In order to achieve this, the method includes a step of reversing the gradation of the second image data.

  The halftone dot printed matter of the present invention is produced using the lightness synthesis data for adjusting the lightness of the visible image and the latent image, so that the second halftone dot portion (4a) can be obtained using a known output machine or printing machine. Even when the image data is produced so that the second background portion (4b) is formed of black (K), the halftone dot portion of the second halftone region (4) under a normal light source. It is possible to visually recognize the background portion as the same color. Therefore, it is possible to improve the concealment property of the latent image under a normal light source and to produce a halftone dot printed material in which the latent image is clearly visible even under an infrared light source.

FIG. 6 is a diagram illustrating a halftone dot printed matter according to Patent Document 1. 9 is a flowchart showing a method for producing a halftone dot printed material according to Patent Document 2. The figure which shows the visible image observed under the halftone dot composition and normal light source in the halftone dot printed matter of patent document 3 The figure which shows the latent image concealed in the visible image and visible image which are observed under the normal light source of halftone printed matter (1). The block diagram which shows an image processing apparatus (S). The flowchart which produces the halftone dot printed matter (1) of this Embodiment. The schematic diagram which shows the reference point of each image data. The schematic diagram which shows lightness synthetic | combination data. The flowchart which shows the preparation methods of lightness synthetic | combination data. The schematic diagram which shows the detail of STEP2-1-1. The schematic diagram which shows the detail of STEP2-1-2. The schematic diagram which shows the detail of STEP2-1-3. The schematic diagram which shows the detail of STEP2-2. The schematic diagram which shows mask data. The schematic diagram which shows a mask processing process. The schematic diagram which synthesize | combines each data. FIG. 3 is a diagram for explaining each image data used in the first embodiment. FIG. 6 is a schematic diagram showing a halftone dot printed matter obtained by a manufacturing method according to Patent Document 2.

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

  First, the halftone dot printed material produced by using the production method of the present invention will be described with reference to FIG. 4. The halftone dot printed material of FIG. 1 described in the background art, the halftone dot composition, the color material to be used, and the formation Since the same applies to the image to be performed, the description thereof is omitted.

  FIG. 4 is a schematic diagram showing a visible image observed under a normal light source and a latent image concealed in the visible image of the halftone print (1) obtained by the production method of the present invention. Fig.4 (a) is a figure which shows the visible image (5) visually recognized when a halftone dot printed matter (1) is observed under a normal light source, and FIG.4 (b) is shown in the visible image (5). It is a figure which shows the hidden latent image image (6).

  The halftone dot printed matter (1) shown in FIG. 4A is similar to the halftone dot printed matter (1) shown in FIG. 1 described above, and a latent image (shown in FIG. The second halftone dot portion (4a) expressing 6) is formed of black (K), and the second background portion (4b) is formed of mixed color black. In the printed matter described in Patent Document 1 described above, the second halftone dot portion (4a) and the second background portion (4b) are visually recognized as the same color under a normal light source, so that a visible image (5 ) Is clearly visible, and the latent image (6) is not visually recognized.

  As described above, in the output using a general printer, dark portions in the image data are automatically output in a state containing black (K) ink, and light portions in the image data are automatically cyan. Since (C), magenta (M) and yellow (Y) mixed color inks are output, the second halftone dot portion (4a) and the second background portion (4b) are under the normal light source. In this case, the visible image (5) is clearly recognized and the latent image (6) is also visually recognized overlapping with the visible image (5). However, in the present invention, by creating the halftone print (1) using the brightness synthesis data described later, the visible image (5) is clearly visible under a normal light source as shown in FIG. 4 (a). The latent image (6) is not visually recognized.

  Further, when the halftone dot printed matter (1) shown in FIG. 4A is observed under an infrared light source, the latent image (6) shown in FIG. 4B is clearly visually recognized. Thus, even when the halftone print (1) obtained by the production method of the present invention is produced using a general printer, the visible image (5) is clearly visually recognized under a normal light source, and the infrared light source Below, the latent image (6) is clearly visible.

  Next, the structure of the apparatus used for producing the halftone print (1) shown in FIG. 4 will be described with reference to FIG. The apparatus shown in FIG. 5 is the image processing apparatus (S) described in Patent Document 2 previously filed by the applicant.

  The image processing apparatus (S) includes an input unit (401), a processing unit (402), a storage unit (403), and an output unit (404). The input unit (401) inputs data necessary for producing the halftone dot printed material (1) of the present embodiment, and provides the data to the processing unit (402). The processing unit (402) stores the given data in the storage unit (403), performs arithmetic processing and image processing necessary for the production of the halftone print (1), and outputs the obtained results to the output unit ( 404). The output unit (404) outputs the data given from the processing unit (402) to an external device such as a printer or a printer (not shown).

  A method for producing a halftone print (1) according to the present embodiment using the image processing apparatus (S) of FIG. 5 will be described with reference to the flowchart of FIG.

  As STEP 1, in order to acquire the image data of the visible image (5) formed by the first halftone region (3), the first image data that is the original image of the visible image (5) is processed by the processing unit (402). The first image data produced or acquired and / or obtained in advance is obtained from the input unit (401) and stored in the storage unit (403) via the processing unit (402).

  In the case where the original image acquired by the input unit (401) is not image data (hereinafter referred to as “digital data”) by bitmap or vector information, it is necessary to convert it to digital data. It is necessary to further have data conversion means for converting the original image into digital data.

  The input unit (401) includes an input unit (401) that acquires first image data that is an original image of the visible image (5) and a data conversion unit that converts the acquired original image into digital data. It may be a reading device such as a scanner or an imaging device such as a digital camera, a video camera, or a portable terminal.

  When image data that has been created and / or acquired in advance is used as the first image data, the input unit (401) is a CD-ROM in which an original image that has been created and / or acquired in advance is already recorded as digital data, Input / output devices such as an MO drive, a CD-ROM drive, an FD drive, and an image card reader that acquire digital data from an information recording medium such as an FD and a USB memory may be used.

  In this case, as described above, since the original image has already been converted into digital data, it is not necessary to go through the processing unit (402). Therefore, after obtaining by the input unit (401), it is stored in the storage unit (403) without going through the processing unit (402). In any creation or acquisition method, the first image data stored in the storage unit (403) includes a plurality of pixels or vector information.

  Pixels are points that are arranged in a grid pattern to form an image, and have information about color as numerical values. Vector information is numerical information representing the shape of a figure. For example, if the figure is a straight line, the shape of each figure is determined by the positions of both ends of the straight line. If the figure is a circle, for example, the shape of the figure is determined by the center position and radius of the circle. Therefore, it is possible to form an image by superimposing a plurality of figures by recording numerical information that determines the figure shape such as each position and radius.

  Examples of an image format for forming an image with pixels include a TIFF format and a BMP format. Examples of an image format for forming an image based on vector information include a PDF format and an EPS format.

  Note that the data in the present embodiment are all stored in the storage unit (403), but are described in the following schematic drawings for detailed description.

  In the processing unit (402), as a method of creating the first image data composed of a plurality of pixels or vector information into image data composed of a plurality of pixels, there is a method according to Halftone Type 16 of the Postscript halftone generation method.

  Postscript is a page description language published by Adobe Systems in 1984. Since it is possible to describe document information with a high degree of freedom by using this PostScript, PostScript is adopted in some laser printers, plate-making film output machines and the like in the printing field. Halftone Type 16 is one type of halftone dot generation method that complies with the PostScript language specification.

  Normally, there is one type of halftone dot used in one printed matter, but the Halftone Type 16 is characterized in that two types of halftone dots can be mixed in one printed matter. Therefore, it is possible to give two types of halftone dots composed of two types of regions to one image. By performing halftone processing on the first image data by a method according to the Halftone Type 16, first image data composed of a plurality of pixels is produced.

  The halftone process is a conversion process performed on an image having shading information. In the present invention, in the processing unit (402), the first image data acquired by the input unit (401) is converted into the first image data at a certain interval specified in advance in a network having an area corresponding to the grayscale information. The process of replacing each point is called halftone processing.

  Next, as STEP 1 ′, in order to acquire image data of the latent image (6) formed by the second halftone area (4), second image data that is an original image of the latent image (6) is obtained. Is obtained from the input unit (401) as second image data from the outside and stored in the storage unit (403) via the processing unit (402). The stored second image data includes a plurality of pixels.

  Note that the second image data is also produced from a plurality of pixels or vector information to image data composed of a plurality of pixels by a method according to HalftoneType 16 as in the case of the first image data described above. Note that the image data is composed of a plurality of pixels on the data, but is composed of a plurality of halftone dots on the output.

  It is not the essence of the present invention whether the first image data and the second image data are composed of pixels or vector information. Therefore, in the following description, the first image data and the second image data are used. Will be described as consisting of a plurality of pixels, and the description in the case of vector information will be omitted.

  In the first image data and the second image data, at least three arbitrary points at a common position are set as reference points in each image data.

  FIG. 7 is a schematic diagram showing reference points in the first image data shown in FIG. 7A and the second image data shown in FIG. 7B. The first image data is an original image that is a first observation condition on the halftone printed matter (1), for example, a base of an image to be recognized under a normal light source. The second original image is an original image that is a basis of an image to be recognized under the second observation condition, for example, an infrared light source, on the halftone print (1).

  When setting a reference point, first, one arbitrary image data is selected from each image data. In FIG. 7, the first image data shown in FIG. 7A is selected, and then any three points are selected. Since each image data is composed of a plurality of pixels, the point here is a single pixel.

In the first image data, first, the first reference point (P1 ¹ ) is set as the coordinates of the zero point (0, 0), and then from the first reference point (P1 ¹ ) in the X direction, A point at a distance X1 is set as a second reference point (P2 ¹ ), and a point at a distance Y1 from the ^first reference point (P1 ¹ ) in the Y direction is set as a third reference point ( P3 ¹ ). Thus, P1 ¹ , P2 ¹ and P3 ¹ were set as reference points in the first image data. The plurality of pixels constituting the first image data have coordinates that are unique position information indicating the distance to the zero point (0, 0).

Next, the reference point of the second image data shown in FIG. 7B is set at a position common to the three reference points set in the first image data. In the second image data, first, the first reference point (P1 ² ) is set as the coordinates of the zero point (0, 0), and then the first reference point is set as in the first image data. A point at a distance of X1 in the X direction from (P1 ² ) is taken as a second reference point (P2 ² ).

Furthermore, the point at a distance of Y1 in the Y direction from the first reference point (P1 ² ) was set as the third reference point (P3 ² ). The distance between the three reference points in each image data is the same. In this way, any three points at positions common to the first image data and the second image data are set as the respective reference points. The plurality of pixels constituting the second image data have coordinates that are unique position information indicating the distance to the zero point (0, 0).

  When each image data has the same size, it is possible to set a reference point at a common position in each image data by setting at least three corners among the four corners in each image data as reference points. It is. The same size means that the number of vertical and horizontal pixels in each image data is the same.

  Further, general image formats such as the TIFF format, the JPEG format, and the BMP format have a characteristic that pixels are always arranged in parallel along two axial directions perpendicular to each other. Therefore, when all the pixels constituting each image data have a characteristic that they are always arranged in parallel along two orthogonal vertical and horizontal axis directions, the vertical and horizontal directions of each image data are self-explanatory, and rotation is performed. Since there is no need to consider, only one reference point is required for each image data. Hereinafter, in the present invention, each image data is described as having the same size and having three reference points.

  Next, as STEP 2, the processing unit (402) created brightness composite data that prevents the latent image (6) from being visually recognized under a normal light source, using the first image data and the second image data. Thereafter, it is stored in the storage unit (403).

FIG. 8A is a schematic diagram showing lightness synthesis data. The lightness synthesis data refers to the lightness compression processing described later from the lightness of the first image data to the lightness of the second image data in order to prevent the latent image (6) from being visually recognized under a normal light source. The image data is composed of pixels having a brightness obtained by subtracting the brightness determined by applying, and three reference points (P1 ³ , P2 ³ , P3) at positions common to the first image data and the second image data. ³ ).

  The brightness in the present invention is a value indicating the brightness of each pixel constituting each image data used when producing the halftone print (1). Here, the brightness is indicated by 256 gradations from 0 to 255.

  In the conventional method for producing a halftone print (1), the halftone print (1) is produced using the first image data and the second image data. In the present invention, The halftone dot printed matter (1) is produced using the brightness synthesis data instead of the image data. Producing using the brightness synthesis data prevents the latent image (6) from being visually recognized under a normal light source.

  As a specific example, first, a halftone print (1) is produced by a conventional production method. Although there is no limitation on the resolution of the lightness synthesis data, the calculation result of the pixels constituting the first image data and the pixels constituting the second image data is stored in the lightness synthesis data as described later. It is desirable that the resolution of the image data and the resolution of the second image data are the same because the calculation amount is small. Note that the resolution in the present invention is a value indicating the size of one pixel in the brightness synthesis data in the halftone print (1).

  For example, when the resolution of the lightness composite data is 0.1 mm, one pixel in the lightness composite data is a size of 0.1 mm × 0.1 mm in the halftone print (1). Therefore, when the resolution is 0.1 mm and the brightness synthesis data is vertical (Y1) 2,000 pixels and horizontal (X1) 3,000 pixels, the halftone dot printed matter shown in FIG. In (1), the length (Y1) is 2,000 pixels × resolution 0.1 mm = 200 mm, and the width (X1) is 3,000 pixels × resolution 0.1 mm = 300 mm.

Hereinafter, for the convenience of explanation, also in the produced halftone print (1), three reference points (P1 ⁴ , P2 ⁴ , P3) are located at the same positions as the first image data, the second image data, and the brightness composite data. ⁴ ) Set. The common position refers to, for example, the upper left, lower left, and lower right three points in the first image data and the second image data as reference points. Therefore, in the halftone print (1), the upper left in the print, The lower left and lower right three points are used as reference points.

Further, by dividing the halftone dot printed matter (1) by a size of 0.1 mm × 0.1 mm which is the resolution in the lightness synthesis data, each divided area is at a position common to the lightness synthesis data. A reference point (P1 ⁴ ) that is a certain zero point can be regarded as having coordinates that are unique position information, and the position in the brightness synthesis data and the position of the halftone print (1) are the common coordinates. It is possible to express using Similarly, the positions of the first image data and the second image data can be expressed using the common coordinates with the halftone print (1).

  Hereinafter, in the description of the present embodiment, the positional relationship between each data and the halftone print is assumed to be described based on the common coordinates described above. For example, the lightness synthesis data and the halftone print are expressed as “the same place”. Represents that the lightness synthesis data and the halftone print have the same coordinate value in common coordinates.

  However, in the halftone dot printed matter (1) of the present invention, the second halftone dot portion (4a) and the second background portion (4b) are not visually recognized as the same color under the normal light source. The lightness and darkness of the color of the second halftone area (4) composed of the part (4a) and the second background part (4b) is determined by the second halftone area (4) in each second halftone area (4). It depends on the size of the area of 4a). Therefore, originally, the halftone dot printed matter (1) is visually recognized with the visible image (5) clearly, and the latent image (6) is also visually recognized with being overlapped with the visible image (5).

  FIG. 8B is a plan view when the halftone dot print (1) obtained by the conventional production method is observed under a normal light source. In the halftone dot printed matter (1) obtained by the conventional production method, the second halftone dot portion (4a) and the second background portion (4b) must appear to be the same color under a normal light source. The brightness of the color of the second halftone region (4) composed of the second halftone dot portion (4a) and the second background portion (4b) depends on the size of the area of the second halftone dot portion (4a). It will be constant regardless.

  However, in the state shown in FIG. 8B, in the halftone print (1) obtained by the conventional production method, the second halftone portion (4a) and the second background portion (4b) are under the normal light source. In this state, the lightness of the color of the second halftone region (4) composed of the second halftone dot portion (4a) and the second background portion (4b) It depends on the size of the area of the second halftone dot portion (4a) in the second halftone region (4). Therefore, in this halftone printed matter, the visible image (5) is clearly visually recognized, and the latent image (6) is also visually recognized overlapping the visible image (5).

  In the halftone dot printed matter (1), the color difference between the second halftone dot portion (4a) and the second background portion (4b) is visually recognized by overlapping the visible image (5) under a normal light source. The latent image (6) is called a ghost image in the present invention.

  The ghost image is a virtual image for explaining the present embodiment in detail, and there is no actual ghost image as a single halftone print (1) or image data. Actually, even when the halftone dot printed matter (1) is observed, the visible image (5) and the ghost image are overlapped with each other, and the halftone dots constituting both images are intricately complicated. It is difficult to accurately separate (5) and the ghost image.

  At this time, how clearly the ghost image is observed under a normal light source is given to the color of the color material applied to the second halftone dot portion (4a) and the second background portion (4b). It is influenced by the color difference under normal light source with the color of the selected color material. The larger the color difference, the clearer the ghost image is observed under the normal light source, and the smaller the color difference, the lighter the ghost image is observed under the normal light source.

  Further, when the color of the color material applied to the second halftone portion (4a) is lower in brightness than the color of the color material applied to the second background portion (4b), the latent image (6). When the color of the color material applied to the second halftone dot portion (4a) is higher in brightness than the color of the color material applied to the second background portion (4b) Then, a ghost image such that the latent image (6) is brightly and darkly inverted is visually recognized.

  In the following description, it is assumed that the color of the color material applied to the second halftone portion (4a) has a lower brightness than the color of the color material applied to the second background portion (4b). Unless otherwise stated, even if the color of the color material applied to the second halftone portion (4a) is higher in brightness than the color of the color material applied to the second background portion (4b) The contents are the same.

  The lightness synthesis data shown in FIG. 8A is based on the visual recognition state shown in FIG. 8B. In the halftone dot printed matter (1), the visible image (5) and the ghost image overlap each other and are visually recognized as dark. The processing unit (402) has a brightness obtained by reversing the brightness of the ghost image to the brightness of the pixels constituting the first image data that is the original image of the visible image (5) and then adding the brightness of the same position portion. It consists of pixels.

  However, since the ghost image itself is merely a virtual image as described above, the second image data is actually used as an alternative to the ghost image. However, if the second image data is used as it is, the influence of the color difference between the second halftone dot portion (4a) and the second background portion (4b), which is a part of the definition of the ghost image, is completely different. Not considered. Actually, when the color difference between the second halftone dot portion (4a) and the second background portion (4b) is large, the ghost image is clearly observed, and when the color difference is small, the ghost image is observed lightly. In order to reflect this in the processing result, the ghost image is substituted by performing the lightness information compression process described later on the second image data.

  In the lightness synthesis data obtained in this way, the low-lightness (dark) portion in the ghost image becomes a high-lightness portion at the time of light-dark reversal. The brightness is higher (brighter) than the pixels at the same location. In addition, in the ghost image where the lightness is high (bright), the lightness is low and the lightness is low. Therefore, the pixels at the same position in the lightness composite data are lighter than the pixels at the same position in the first image data. It is not high (bright).

  Therefore, by producing the halftone print (1) using the brightness synthesis data instead of the first image data, the halftone print (1) created using the first image data is lower than the ghost image. In the halftone dot printed matter (1) created using the lightness synthesis data, the portion that can be seen by lightness is higher in lightness synthesis data at the same location than the first image data at the same location by the above-described processing. When a ghost image and brightness composite data appear to overlap under a normal light source, the brightness decrease due to the low brightness of the ghost image overlaps with the brightness increase due to the high brightness of the first image data. As a result, only the first image data is visually recognized. That is, in the halftone print (1), the ghost image is not visually recognized under the normal light source, and only the visible image (5) is visually recognized.

  In such an image (referred to as image A), a portion with high brightness of another image is arranged at a substantially same position in a portion with low brightness of another image, so that an intermediate value that is the average of the two values with the naked eye. In addition, a portion with a high lightness of another image (referred to as image B) is arranged at a substantially same position in a portion with a low lightness of image A. By visually recognizing a certain intermediate brightness, only the intermediate brightness is observed at any location is expressed as “cancelling” the brightness of the image A.

  Next, a method for creating lightness synthesis data will be described in detail according to a flowchart showing a method for creating lightness synthesis data shown in FIG.

  As STEP 2-1, a first image which is the original image of the visible image (5) stored in the storage unit (403) in order to perform correction for canceling the brightness and darkness of the ghost image with respect to the first image under a normal light source. After the brightness of the first image data and the second image data corresponding to the ghost image that is the original image of the latent image (6) is adjusted by the processing unit (402) to create the brightness adjustment data, Store in the storage unit (403).

  As described above, the brightness adjustment data is obtained from the visible image (5) under the normal light source due to the color difference between the second halftone portion (4a) and the second background portion (4b) in the halftone print (1). ) Is image data obtained by performing processing on the first image data to cancel the brightness and darkness of the ghost image that is visually recognized.

  In the present invention, the ghost image is generated under a normal light source by producing the halftone dot printed matter (1) by the conventional method for producing the halftone dot printed matter (1) using the lightness synthesized data instead of the first image data. Is canceled, and only the visible image (5) is visually recognized.

  The step shown in STEP 2-1 for adjusting the lightness of the second image data is the highest lightness pixel in the plurality of pixels constituting the second image data, and the highest lightness in the plurality of pixels constituting the first image data. The first lightness not higher than the high lightness is replaced, and the lowest lightness pixel in the plurality of pixels constituting the second image data is not lower than the lowest lightness in the plurality of pixels constituting the first image data. The lightness that does not correspond to the highest or lowest lightness in the plurality of pixels constituting the second image data is replaced with the second lightness, and the lightness that does not correspond to the first lightness, the second lightness, the first lightness, and the second lightness It is a step of creating brightness adjustment data by replacing with any brightness between brightness.

  Specifically, brightness information of each pixel constituting the second image data is extracted from the second image data stored in the storage unit (403) by the processing unit (402) and stored in the storage unit (403). STEP2-1-1 and the second image data stored in the storage unit (403) are inverted in brightness by the processing unit (402) and stored in the storage unit (403). 403), the brightness information is compressed by the processing unit (402) from the second image data stored in the storage unit (403) and stored in the storage unit (403).

  10, FIG. 11 and FIG. 12 are schematic diagrams showing details of the brightness adjustment method in STEP 2-1. FIG. 10 is a schematic diagram showing details of STEP2-1-1. In STEP 2-1-1, in order to predict how dark the latent image (6) is visually recognized at which position of the halftone print (1) under a normal light source, first, as shown in FIG. Only lightness information is extracted from the second image data shown by the processing unit (402) to create lightness extraction data.

The brightness information is data indicating how much the brightness of each pixel constituting each image data is. A method of extracting only brightness information from the second image data may be obtained by calculation using a known calculation method based on the color information of each pixel constituting the second image data. Further, after the halftone dot printed matter (1) is prepared, the lightness of each halftone dot constituting the halftone dot printed matter (1) is measured using a known lightness measuring device, and the actually measured value obtained may be used. good. As an example of a method for extracting brightness by calculation, for example, there is a method of converting the color of a pixel constituting each image data into a CIE 1976 L ^* a ^* b ^* color system and using the value of L ^* as the brightness. .

The CIE 1976 L ^* a ^* b ^* color system is a color space recommended by the CIE (International Commission on Illumination) in 1976, and because it is specified in JIS Z 8729 in the Japanese Industrial Standards, it is here. Then, description of the concrete conversion method to CIE1976L ^* a ^* b ^* color system is abbreviate | omitted.

  Each pixel constituting the lightness extraction data produced by extracting only the lightness information of the second image data shown in FIG. 9 has lost the information about the color from the second image data, so that the second image The data is a monochrome multi-tone image.

  As described above, in the brightness synthesis data, the correction that cancels the brightness and darkness of the ghost image is performed on the first image data that is the original image of the visible image (5), so the visible image (5) and the ghost image are corrected. When the ghost image is visually recognized dark under a normal light source, the brightness of each pixel constituting the first image data that is the original image of the visible image (5) is increased by the processing unit (402) ( After correcting the brightness, the first image data composed of the corrected pixels is produced.

  On the contrary, the first image which is the original image of the visible image (5) by the processing unit (402) at the place where the visible image (5) and the ghost image overlap so that the ghost image is viewed brightly under a normal light source. After correcting the brightness of each pixel constituting the data to be darker (lower brightness), first image data including the corrected pixels is created.

  That is, the brightness synthesis data is obtained by adding the brightness of each pixel constituting the image obtained by inverting the brightness of the ghost image to the brightness of each pixel constituting the first image. As described above, when the color of the color material applied to the second halftone portion (4a) has a lightness lower than the color of the color material applied to the second background portion (4b), the ghost image is The color of the color material which is visually recognized as the same image as the latent image (6) and is applied to the second halftone portion (4a) is more than the color of the color material applied to the second background portion (4b). If the brightness is high, the ghost image is visually recognized as an image obtained by reversing the latent image (6).

  Therefore, when the color of the color material applied to the second halftone portion (4a) is lower in brightness than the color of the color material applied to the second background portion (4b), the first image Then, since the lightness composite data is obtained by adding the lightness and darkness of the latent image (6), that is, by reversing the lightness and darkness of the lightness extraction data, STEP2-1-1 is followed by STEP2-1. -2, the brightness of the brightness extraction data is inverted by the processing unit (402).

  When the color of the color material applied to the second halftone portion (4a) has a higher brightness than the color of the color material applied to the second background portion (4b), Thus, the brightness composite data can be obtained by adding the lightness and darkness of the latent image (6), that is, the image obtained by reversing the lightness and darkness of the lightness extraction data twice, but generally the image obtained by reversing the lightness and darkness of the image twice. Is identical with the original image, STEP 2-1-2 is not performed in this case.

  FIG. 11A is a schematic diagram showing brightness extraction data, and FIG. 11B is a schematic diagram showing brightness extraction data after light / dark reversal.

  As the light / dark reversal method, there is a method of subtracting the lightness value of each pixel of the image data to be light / dark reversal from a predetermined constant to obtain a new lightness. For example, assuming that the pixels constituting the image data that is the object of light / dark reversal are composed only of pixels having a lightness of 0 or more and 255 or less, and the predetermined constant is 255, the image data that is the object of light / dark reversal is Among the constituent pixels, a pixel having a lightness of 0 (black) has a lightness (white) of 255-0 = 255 after light / dark reversal. Similarly, a portion having a lightness of 255 (white) has 255−255 = A lightness of 0 (black) is assumed.

  Hereinafter, in the present invention, a case will be described in which the color material forming the second halftone dot portion (4a) has lower brightness than the color material forming the second background portion (4b). Even if the color material forming the second halftone dot portion (4a) has a higher brightness than the color material forming the second background portion (4b), processing other than the presence or absence of STEP2-1-2 The description is omitted because there is no difference in contents, but when there is no STEP2-1-2, the brightness extraction data after the brightness inversion in the description of the present embodiment is replaced with the brightness extraction data.

  FIG. 12 is a schematic diagram showing details of STEP2-1-3, and FIG. 12A is a schematic diagram showing brightness extraction data after light-dark reversal. In STEP2-1-3, in order to prevent the ghost image from being visually recognized by overlapping the visible image (5) of the halftone print (1) under a normal light source, the brightness information of the brightness extraction data after the brightness inversion is After being compressed by the processing unit (402) to create brightness adjustment data, it is stored in the storage unit (403).

  As described above, according to the present invention, in the ghost image in which the lightness is low (dark), the pixels at the same position of the lightness synthesis data are made higher (lighter) than the pixels at the same position of the first image data. In the ghost image where the brightness is high (bright), the pixels at the same location in the brightness synthesis data also have a higher brightness (brighter) than the pixels at the same location in the first image data. The amount of increase in lightness for pixels at the same location in the first image data in a portion with low lightness is greater than the amount of increase in lightness for pixels at the same location in the first image data in a portion with high lightness in the ghost image. .

  As a result, when the halftone print (1) is produced using the lightness composite data instead of the first image data, even when the lightness composite data and the ghost image are visually recognized under a normal light source, The lightness and darkness of the ghost image cancels the lightness and darkness of the brightness synthesis data, and the ghost image is not recognized by the naked eye, and only the visible image (5) is visually recognized.

  As will be described later, the brightness synthesis data is obtained by adding the brightness of the brightness adjustment data to the brightness of the first image data. Therefore, the brightness increase amount for the pixels at the same location in the first image data matches the brightness adjustment data.

  In addition, when considering a halftone print (1) in the present invention in which a ghost image is not recognized at all even when observed with the naked eye, the brightness adjustment data used for producing such a halftone print (1) is “ If it is defined as “optimal brightness adjustment data”, since the ghost image is not recognized at all, it can be said that the optimal brightness adjustment data completely cancels the brightness and darkness of the ghost image.

  Suppose that lightness adjustment data having a lightness difference smaller than the lightness adjustment data optimal for the production of the halftone print (1), that is, data obtained by excessively compressing lightness information of the lightness extraction data after light / dark reversal is used. As compared with the case where the optimum brightness adjustment data is used, the cancellation of the ghost image becomes insufficient, and the ghost image is visually recognized on the halftone print (1).

  On the other hand, brightness adjustment data having a brightness difference larger than the brightness adjustment data optimum for the production of the halftone print (1), that is, data with insufficient compression of the brightness information of the brightness extraction data after the brightness inversion is used. If so, the ghost image cancels excessively as compared with the case where the optimum brightness adjustment data is used, and an image in which the brightness of the ghost image is reversed is visually recognized on the halftone print (1). .

  Therefore, as STEP2-1-3, it is a process necessary to increase the lightness of the same portion of the first image data with respect to the lightness of the ghost image by compressing the lightness information without excess or deficiency. . The brightness adjustment data obtained in STEP 2-1-3 is added to the brightness of the first image data in STEP 2-2, which will be described later, whereby brightness combined data is obtained.

  Compressing the brightness information is to reduce the width of the gradation constituting the image while maintaining the gradation of the image data. The known linear brightness compression method shown in FIG. There is a known arbitrarily-specified lightness compression method shown in (d). Specifically, when the image data is composed only of pixels having a lightness of 0 or more and 255 or less, the pixels composed only of lightness of 0 or more and 255 or less are set as a narrower range, for example, 32. This refers to image processing that is replaced with a pixel composed of only lightness of 223 or less or a pixel composed of lightness of 0 or more and 100 or less.

  FIG. 12B is a diagram illustrating the brightness adjustment data created by compressing the brightness information of the brightness adjustment data after the brightness inversion shown in FIG. As described above, the ghost image is clearly observed when the color difference between the second halftone dot portion (4a) and the second background portion (4b) is large, and is lightly observed when the color difference is small. The At this time, the color difference described above, that is, the appearance of the ghost image is complicatedly influenced by a plurality of factors such as the color material and the base material used for printing.

  As described above, the lightness information is compressed by the color material for forming the second halftone region (4) for forming the latent image (6) and the conventional manufacturing method shown in FIG. 8 (b). The halftone dot printed matter (1) is appropriately set in accordance with the visible state of the visible image (5) and the latent image (6) when observed under a normal light source.

  Note that the processing order may be different in STEP 2-1-1, STEP 2-1-2, and STEP 2-1-3. For example, after STEP 1, STEP 2-1-3 is the second image data. After the lightness information is compressed, as STEP2-1-1, only the lightness information is extracted from the second image data in which the lightness information is compressed to produce lightness extraction data, and then, as STEP2-1-2, The brightness adjustment data may be created by inverting the brightness of the brightness extraction data. Even in that case, it is possible to adjust the brightness as in the case of the above-described order.

  However, when the lightness extraction data, which is STEP2-1-1, is first produced, it is possible to perform subsequent STEPs using the second image data having only lightness information. Thereby, the amount of data of the second image data is reduced, and it is possible to produce data at a higher image processing speed than in the case where STEP2-1-1 is used as a subsequent process. Therefore, it is preferable to perform STEP2-1-1 first from the viewpoint of image processing speed.

  Hereinafter, in the present embodiment, brightness extraction data is created from the second image data in STEP 2-1-1, then the brightness of the brightness extraction data is inverted in STEP 2-1-2, and finally, STEP 2 In the following description, it is assumed that the brightness adjustment data is created by compressing the brightness of the brightness extraction data after the brightness inversion.

  Next, as STEP2-2, the brightness adjustment stored in the storage unit (403) by the processing unit (402) in order to remove the influence of the ghost image that is visually recognized overlaid on the visible image (5) under a normal light source. The brightness of the data is added to the brightness of the first image data, and brightness combined data is created and stored in the storage unit (403).

  FIG. 13 is a schematic diagram showing details of STEP2-2. FIG. 13A is a schematic diagram showing brightness adjustment data stored in the storage unit (403). Since the brightness adjustment data has only information on brightness and no information on color, it becomes a gray gradation image. FIG. 13B is a schematic diagram showing the first image data stored in the storage unit (403).

  Next, in order to synthesize the brightness adjustment data shown in FIG. 13 (a) and the first image data shown in FIG. 13 (b), brightness addition processing is performed by the processing unit (402). Create the lightness synthesis data shown.

The lightness addition processing is the lightness possessed by each of the plurality of pixels constituting the lightness adjustment data shown in FIG. 13A and the lightness possessed by each of the plurality of pixels constituting the first image data shown in FIG. Is a process of adding. The brightness addition process can be performed using a known image processing method. For example, the brightness compression data shown in FIG. 13A and the color of the first image data shown in FIG. Is converted to the CIE 1976 L ^* a ^* b ^* color system described above, and the value of the lightness L ^* of the two image data is added.

  Depending on the lightness of the pixels constituting each image data, when the lightness compression data and the lightness of the first image data are added by the lightness addition process, the lightness of the pixels exceeds 255 and is stored in the lightness synthesis data. You may not be able to. Therefore, when the result of the lightness addition process exceeds the lightness value 255, if the lightness is 20 or more and 275 or less in all pixels as a result of the lightness addition process, the value obtained by subtracting 20 which is the minimum lightness from the addition result Well-known image processing so that the lightness does not exceed 255 by appropriate means, such as a method for converting the lightness of the first image data so that the lightness addition processing result does not exceed 255 Adjust by the method.

  Next, as STEP 3, the positions, shapes, dimensions, etc. of the plurality of second halftone regions (4) and the second halftone portions (4a) and the second halftone regions (4) constituting each second halftone region (4) are described. The processing unit (402) creates or obtains mask data indicating the position, shape, dimensions, and the like of the second background portion (4b) from the input unit (401) as mask data from the outside, and stores the mask data via the processing unit (402). Stored in the section (403).

  FIG. 14A is a schematic diagram showing mask data. The mask data is an image used when the latent image (6) is arranged in the plurality of second halftone areas (4). The mask data is created using the format data shown in FIG. Format data refers to how to arrange a plurality of first halftone areas (3) and a plurality of second halftone areas (4) for producing a halftone print (1) in the present invention. It is the set data.

  How the format data includes a first halftone area (3) that forms a visible image (5) and a second halftone area (4) that is an area that forms a latent image (6). Format data is created by designing whether to arrange. The format data is composed of a plurality of pixels. It should be noted that the halftone areas (3, 4) in the format data are prepared so as to be the halftone dot printed matter in Patent Document 1 filed earlier.

  After the format data prepared in advance is acquired by the input unit (401), mask data is generated using the format data. As described above, the mask data is an image used when the latent image (6) is arranged in the plurality of second halftone areas (4). Therefore, in the format data, the pixels at the arrangement positions of the plurality of second halftone areas (4) are black pixels, and the pixels at the arrangement positions of the plurality of first halftone areas (3) are white pixels. The mask data shown in FIG. 14A is produced. The mask data has reference points (P1, P2, P3) corresponding to the reference points of each original image.

  Next, as STEP 4, mask data is used to form the second image data by the second halftone portion (4 a) and the second background portion (4 b) of the plurality of second halftone regions (4). The processing unit (402) performs a mask process using and stores it in the storage unit (403).

  The mask processing refers to the second image if the pixel constituting the mask data is a black pixel among the two pixels at the same position by combining the reference point of the mask data and the reference point of the second image data. If the pixels constituting the data are left and the pixels constituting the mask data are white pixels, the process of replacing the pixels constituting the second image data with white pixels is performed for all the pixels constituting the second image data. By applying, all the portions corresponding to the plurality of first halftone areas (3) in the second image data are replaced with white.

  Thereby, the second image data is converted into an image including only the second halftone portion (4a) arranged in the plurality of second halftone regions (4), and the first image data and A plurality of halftone dots forming the second image data can be assigned to the print area without being mixed. Therefore, it is possible to produce a printed matter in which either the visible image (5) or the latent image (6) can be visually recognized according to the observation conditions corresponding to the characteristics of the material forming each halftone dot portion.

  FIG. 15 is a schematic diagram showing a mask processing step. In FIG. 15, in order to describe in detail, each black pixel is indicated by oblique lines, and the black pixels in the mask data shown in FIG. 15A are surrounded by thick lines. In the mask processing step, the reference point of the mask data shown in FIG. 15A acquired by the processing unit (402) is matched with the reference point of the second image data.

  Next, the reference points (P1, P2, P3) of the mask data shown in FIG. 15A and the reference points (P1, P2, P3) of the second image data shown in FIG. 15B are matched. FIG. 15C is a schematic diagram when the mask data image and the second image data are combined. When the two data are combined, if the pixel constituting the mask data among the two pixels at the same position is a black pixel (inside the bold line), the pixel constituting the second image data is left. If the pixel constituting the mask data is a white pixel (outside the thick line), the second image data is set as a white pixel.

  By performing the mask process, a portion of the second image data that does not correspond to the second halftone region (4), that is, a pixel that forms the first halftone region (3) becomes a white pixel. Therefore, the second image data including a plurality of second halftone dots (4a) shown in FIG. Although not shown, also in the second image data composed of a plurality of second halftone dot portions (4a), the reference points (P1, P2, P3) corresponding to the reference points of the original images are the same as other data. ). In order to explain in detail, in FIG. 15D, the black pixel portion of the mask data is indicated by a bold line, but it does not actually exist.

  Next, in STEP5, the lightness synthesis data, the mask data, and the second image data after the mask processing created in STEP4 are synthesized to produce synthesized data. FIG. 16 is a schematic diagram for combining the data. First, the brightness synthesis data, the mask data, and the second image data after the mask processing are acquired in the input unit (401). Next, after superimposing the reference points of the brightness synthesis data and the mask data by the processing unit (402), the processing unit (402) performs synthesis processing to synthesize two images. Note that, as a synthesis processing method, for example, there is a method of performing synthesis processing by XOR operation.

  The XOR operation is one of logical operations, and outputs 1 (black pixel) only when the value of the combination of 1 (black pixel) and 0 (white pixel) input does not match. It is a method.

  For example, when two images of lightness synthesis data and mask data are synthesized by XOR operation, the colors of the corresponding two dots are compared, and if both are black pixels or both are white pixels, they are converted into white pixels. If only one of the pixels is a black pixel, it is synthesized by replacing it with a black pixel, and data in which two data are synthesized is produced. In this way, by using the XOR operation, it is possible to synthesize two pieces of data with a single operation. In order to perform the XOR operation, it is necessary to use an image processing apparatus (S) that can replace white pixels and black pixels by rewriting color information of specific pixels.

  Although not shown in the figure, also in data produced by combining two images of lightness synthesis data and mask data, the reference points (P1, P2) corresponding to the reference points of each original image are the same as other data. , P3).

  Next, the data produced by synthesizing the two images of the brightness synthesis data and the mask data and the second image data after the mask processing produced in STEP 4 are synthesized. Similar to the case where the two images of the lightness composite data and the mask data are combined as described above, the data prepared by combining the two images of the lightness composite data and the mask data and the data prepared in STEP 4 are used. After superimposing the reference points of the second image data after the mask processing, the processing unit (402) performs a combining process to combine the two images.

  By combining the lightness composite data and the second image data after the mask processing by the processing unit (402), composite data that is basic data of the halftone print (1) is produced.

  The completed composite data includes two pieces of image information including a visible image (5) and a latent image (6). The composite data is output as STEP 6 from the output unit (404) of an external printing machine or the like, and the halftone print (1) is completed.

  For example, the composite data produced by the image processing apparatus (S) is transferred to and input to a desired plate making apparatus such as an offset plate making apparatus or a screen plate making apparatus, whereby cyan (C), magenta (M), yellow (Y) And a printing plate such as black (K) is output. Next, the printed printing plate and the output unit (404) capable of performing desired printing suitable for the printing plate using the material forming the halftone dot portion and the background portion in each region, A halftone dot printed matter (1) is obtained by printing on the screen.

  Further, the composite data produced by the image processing apparatus (S) is transferred and input to a printer which is an output unit (404), and the material for forming the halftone dot portion and the background portion in each region is used on the base material. A halftone print (1) is produced by printing.

  As described above, according to the present embodiment, the data of the halftone printed matter (1) is generated using the lightness synthesis data, so that the second halftone region (4) is observed in the observation under the normal light source. The second halftone dot portion (4a) and the second background portion (4b) included are visually recognized as the same color, and the concealability of the latent image (6) can be improved.

  A halftone dot printed material as an example produced based on the above embodiment will be described below.

  Using the image processing apparatus (S) shown in FIG. 5, a halftone print was produced according to the procedure shown in FIG. FIG. 17A shows the first image data that is the original image of the visible image (5) used in Example 1, and FIG. 17B shows the first image that is the original image of the latent image (6). 2 image data.

  The first image data is RGB image data having a resolution of 2540 dpi, and a character A is drawn. The character portions of A are all pixels having RGB values 128, 128, and 128 (gray), and are portions other than the characters of A. Are all composed of pixels of RGB values 210, 210, 210 (light gray). The second image data is RGB image data with a resolution of 2540 dpi, and a B character is drawn. The B character parts are all pixels having RGB values of 0, 0, 0 (black), and other than the B character. These parts are all composed of pixels of RGB values 255, 255, 255 (white).

As STEP 1, the first image data and the second image data are acquired from the outside by the input unit (401) and stored in the storage unit (403) via the processing unit (402). Note that the first image data and the second image data, which are RGB image data, were stored in the storage unit (403) in the TIFF format.

  Next, brightness synthesis data was prepared as STEP2. First, as STEP 2-1, the brightness of the second image data was adjusted by the processing unit (402) and stored in the storage unit (403). Specifically, as STEP2-1-1, only the brightness information was extracted from the second image data by the processing unit (402), and brightness adjustment data was produced. The brightness is defined as an average value of RGB values, and pixels of RGB values 0, 0, 0 (black) in the second image data original image are set to brightness 0, and RGB values 255, 255, 255 (white). For the pixel of, only brightness information was extracted by setting the brightness to 255.

  Next, as STEP2-1-2, the brightness of the brightness adjustment data was inverted by the processing unit (402). Further, as STEP2-1-3, the brightness information of the brightness adjustment data after the light / dark inversion was compressed by the processing unit (402) to create the brightness compressed data, and then stored in the storage unit (403). In STEP2-1-2 and STEP2-1-3, the following formula was used.

  The above formula is obtained by dividing the R value + G value + B value of each pixel by 3 in order to obtain the average brightness of RGB for each pixel constituting the second image data, In this process, the brightness information is inverted by subtracting from 255, and the brightness information is compressed by further multiplying by (40 ÷ 255). As a result, in each pixel constituting the lightness compression data, the portion of RGB values 0, 0, 0 (black) (B character portion) has lightness 40, and the portion of RGB values 255, 255, 255 (white) (B The portion other than the character of) has a lightness of 0.

  Next, as STEP2-2, the lightness compression data and the first image data stored in the storage unit (403) are subjected to lightness addition processing by the processing unit (402), and the lightness composite data shown in FIG. Produced. At this time, the brightness value of the pixels constituting the lightness compression data was added to each of the R value, G value, and B value of the pixels constituting the first image data. As an example, the result of adding brightness 40 to pixels with RGB values 128, 128, and 128 resulted in pixels with RGB values 168, 168, and 168. Further, the result of adding brightness 40 to the pixels of RGB values 210, 210, and 210 is the pixel of RGB values 250, 250, and 250.

  Next, as STEP 3, the positions, shapes, dimensions, etc. of the plurality of second halftone regions (4) and the second halftone dot portions (4 a) and the second halftone regions (4) constituting each second halftone region (4). Mask data indicating the position, shape, dimensions, etc. of the second background portion (4b) was acquired from the outside by the input unit (401), and stored in the storage unit (403) via the processing unit (402). The first halftone area (3) was 40 × 40 pixels, and the second halftone area (4) was 15 × 15 pixels.

  Next, as STEP 4, mask data is used to form the second image data by the second halftone portion (4 a) and the second background portion (4 b) of the plurality of second halftone regions (4). The processing unit (402) performed a mask process using and stored in the storage unit (403).

  Next, in STEP5, the lightness synthesis data, the mask data, and the second image data after the mask processing created in STEP4 were synthesized to produce synthesized data. Next, based on the produced synthetic data, printing plate data was produced by the method described in Patent Document 2 previously filed by the present applicant. The second halftone area (4a) of the second halftone area (4) has RGB values of 0, 0, 0 (black), and the second background part (4b) has RGB values of 128, 128. 128 (ash). The printing plate data thus obtained is shown in FIG. 17 (d), and an enlarged view of that portion is shown in FIG. 17 (e).

  Finally, as STEP 6, printing was performed on the obtained printing plate data using a printing function of Photoshop (registered trademark), which is image processing software manufactured by Adobe (registered trademark). Using a color laser printer IPSiO SP C411 (registered trademark) manufactured by RICOH (registered trademark) as an output unit (404), printing was performed on color laser copier paper (product number TKCLA3) manufactured by Canon (registered trademark).

  When the halftone dot print thus produced was observed with the naked eye under a normal light source, a gradation image having the same appearance as the printing plate data shown in FIG. 17D was visually recognized. The latent image (6) formed by the second halftone portion (4a) in the second halftone region (4) was not confirmed with the naked eye, as shown in FIG. 17 (d).

  When this printed matter was observed with the naked eye using an infrared camera, the latent image (6) formed by the second halftone dot portion (4a) in the second halftone region (4) was visually recognized. The visible image (5) by the halftone area (3) was not confirmed.

  Next, as a comparative example, Patent Document 2 filed earlier by the present applicant using the first image data shown in FIG. 17A and the second image data shown in FIG. According to the method described in 1), printing plate data when no brightness adjustment was performed was prepared, and further, a halftone print was prepared. At this time, printing plate data and halftone prints were produced under the same conditions as in the case of adjusting the brightness except that the first image data was used instead of the brightness composite data. FIG. 18A shows the printing plate data when the brightness adjustment is not performed, and FIG. 18B shows a partially enlarged view thereof.

  When the produced halftone print was observed with the naked eye under a normal light source, a gradation image having the same appearance as the printing plate surface data shown in FIG. 18A was visually recognized. The latent image (6) by the second halftone dot portion (4a) in the second halftone region (4) is visually recognized in the same manner as shown in FIG. 18 (a), overlapping the visible image (5). It was done.

  From the above example, by adjusting the brightness, the latent image (6) is hardly visually recognized on the visible image under the normal light source as shown in FIG. The anti-counterfeiting effect brought about can be confirmed. The first embodiment described above is an example of the present invention, and does not limit the technical scope of the present invention. Various modifications can be made within the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Halftone print 2 Base material 3 1st halftone area 3a 1st halftone area 4 2nd halftone area 4a 2nd halftone area 4b 2nd background part 5 Visible image 6 Latent image S Image Processing device 401 Input unit 402 Processing unit 403 Storage unit 404 Output unit

Claims (2)

A plurality of the first halftone area and the second halftone area are arranged adjacent to each other on the substrate, and the first halftone area forms a visible image with the first color material. 1 halftone dot portion, the second halftone area has a second halftone dot portion and a second background portion that form a latent image, and the second halftone dot portion is a predetermined halftone dot portion. The second color material having the first functionality visible under the observation conditions is formed, and the second background portion is formed by the third color material not having the first functionality . A method for producing a halftone print,
Obtaining or producing first image data that is an original image of the visible image composed of a plurality of pixels and second image data that is an original image of the latent image composed of a plurality of pixels;
In order to prevent the latent image from being visually recognized in the visible image under conditions other than the predetermined observation conditions, the second image data is corrected based on the brightness of the first image data. Subtracting the brightness of the image data to create brightness composite data;
The position, shape and size of each of the plurality of second halftone regions, and the position and shape of the second halftone dot portion and the second background portion included in each of the second halftone regions. And obtaining or creating mask data relating to dimensions;
In order to make the second image data into image data formed in a plurality of the second halftone areas, after the second image data and the mask data are overlapped, in the second image data Performing mask processing for replacing all portions corresponding to white pixels in the mask data with white pixels;
Synthesizing the mask data, the second image data after the mask processing, and the brightness synthesis data, and creating synthesized data;
Outputting the composite data to the substrate by a predetermined method;
With
Furthermore, the step of creating the brightness synthesis data includes:
The highest brightness in the plurality of pixels constituting the second image data is replaced with the highest brightness in the plurality of pixels constituting the first image data, and in the plurality of pixels constituting the second image data Replacing the lowest brightness with the lowest brightness in a plurality of pixels constituting the first image data to create brightness adjustment data; and
Adding the brightness of the brightness adjustment data to the brightness of the first image data to produce the brightness composite data;
With
Further, the step of creating the brightness adjustment data includes:
Extracting lightness information from the second image data;
The step of compressing the brightness of the second image data by reducing the difference in brightness between the pixel having the highest brightness and the pixel having the lowest brightness among the plurality of pixels constituting the second image data. When,
A method for producing a halftone print. When the color material forming the second halftone dot portion has a lightness lower than the color material forming the second background portion, between the step of extracting the lightness information and the step of compressing the lightness,
In order to make the brightness of the plurality of pixels constituting the first image data higher than the brightness of the plurality of pixels constituting the second image data, the gradation of the second image data is inverted. The method for producing a halftone dot printed material according to claim 1, further comprising a step.

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