WO2022215378A1

WO2022215378A1 - Platemaking method, platemaking system, and can body

Info

Publication number: WO2022215378A1
Application number: PCT/JP2022/007323
Authority: WO
Inventors: 由樹子齋藤; 良太長塚; 健一郎山本
Original assignee: 東洋製罐株式会社
Priority date: 2021-04-07
Filing date: 2022-02-22
Publication date: 2022-10-13
Also published as: JP2022160882A; TW202311060A; JP7163445B2

Abstract

The present invention is to produce a printing plate on which registering is easy and color reproducibility is high, while opacity of ink is suppressed.　The invention provides a platemaking method for producing a printing plate capable of expressing a color in each pixel by overprinting halftone dots of at least three process colors, wherein the printing plate is produced on the basis of a joining scheme in which, in pixels in which the total value of the halftone dot area ratio of each color of the process colors is 100% or less, the halftone dots of each color are formed in positions that do not overlap each other and halftone dots of each color of the process colors are overprinted.

Description

Plate-making method, plate-making system and can body

The present invention relates to a plate making method, a plate making system and a can body.

A printing plate attached to a printing machine that performs multi-color printing is produced according to image data obtained by dividing an original image by color into halftone dots (for example, Patent Document 1).

In Japanese Patent Laid-Open No. 2002-100001, image data obtained by dividing an original image into dots by color is subjected to image contraction processing so as not to cause ink turbidity due to ink bleeding or mechanical misalignment of a printing machine. A plate-making method is described in which a printing plate is prepared for each color based on the image data subjected to the .

Japanese Patent Publication No. 7-57543

In the technique described in Patent Document 1, since image contraction processing is performed on halftone image data, the background color is likely to be exposed, and the color gamut, which is the area of reproducible colors, is likely to be restricted. Reproducibility tends to be low. Conversely, in the technique described in Patent Document 1, turbidity of ink tends to occur unless image contraction processing is performed in order to maintain high color reproducibility. Further, in the technique described in Patent Document 1, if the image contraction processing is not performed, high-precision registration may be required to adjust the mechanical misalignment of the printing press.

The present invention has been made in view of the circumstances described above, and an example of the task is to solve the problems described above. That is, one example of the object of the present invention is to produce a printing plate that suppresses ink turbidity, facilitates registration, and has high color reproducibility. Another object of the present invention is to provide a can body printed by a technique that suppresses turbidity of ink, facilitates registration, and achieves high color reproducibility.

One aspect of the present invention is a platemaking method for producing a printing plate capable of expressing the color of each pixel by overprinting halftone dots of at least three process colors, wherein the halftone dot area ratio of each color of the process colors is Halftone dots of each color are formed at positions where the halftone dots of each color do not overlap each other in the pixels where the total value is 100% or less, and the halftone dots of each color of the process colors are overprinted to produce the printing plate based on a knockout method. To provide a plate making method.

According to the present invention, it is possible to produce a printing plate that is easy to register and has high color reproducibility while suppressing ink turbidity. Further, according to the present invention, it is possible to provide a can body printed by a method that suppresses turbidity of ink, facilitates registration, and achieves high color reproducibility.

It is a figure which shows the structure of the prepress system which concerns on this embodiment. It is a figure for demonstrating a subtraction method and a multiplication method. FIG. 10 is a diagram for explaining gaps and bites formed in one color and the other color that are objects of the punching-out method; FIG. 5 is a diagram showing the relationship between the total value of the halftone dot area ratio of one color and the halftone dot area ratio of the other color, and the dimension of the gap or the dimension of the encroachment; It is a figure for demonstrating the three-color extraction method. It is a figure for demonstrating the three-color extraction method. FIG. 10 is a diagram for explaining another example of halftone dot shapes in the three-color extraction method; It is a figure which shows the flow of the plate-making method which produces a printing plate using the plate-making system shown by FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below show some examples of the present invention and do not limit the content of the present invention. Moreover, not all the configurations and operations described in the embodiments are essential as the configurations and operations of the present invention.

[Prepress system configuration]
FIG. 1 is a diagram showing the configuration of a prepress system 1 according to this embodiment. FIG. 2 is a diagram for explaining the subtraction method and the multiplication method.

The plate-making system 1 is a system that makes a printing plate that is attached to a plate-type printing machine. The prepress system 1 is a system employing DTP (Desktop Publishing) and CTP (Computer To Plate). The plate making system 1 is a system for making a printing plate for multicolor printing.

The material to be printed on the printing plate produced by the plate making system 1 is a can body (including an intermediate can body) having a substantially cylindrical shape such as a two-piece can, or a flat metal plate. Further, the plate making system 1 is a system for producing a printing plate attached to an offset printing press that transfers ink via an intermediate transfer member (for example, blanket) or a non-offset printing press that does not use an intermediate transfer member.

FIG. 1 shows a printing plate attached to an offset printing machine 30 which uses a can body having a substantially cylindrical shape such as a two-piece can as an object to be printed, and transfers ink to the outer peripheral surface of the can body via an intermediate transfer body. A prepress system 1 for producing is exemplified. The printing plate produced by the plate-making system 1 shown in FIG. 1 is preferably a resin letterpress printing plate having a photosensitive resin layer or the like formed in the image area on which ink is applied. The plate-making system 1 shown in FIG. 1 is a DLE (Direct Laser Engraving) method in which a printing plate is produced by sublimating a resin with laser heat and engraving, or a LAMS method in which an image is written and developed on the surface of a resin plate with a laser. (Laser Ablation Masking System) system, preferably a system for producing a printing plate. Further, the printing plate produced by the plate-making system 1 shown in FIG. good.

The plate-making system 1 includes a data processing device 10 that performs various image processing on document image data to create image data for plate-making, and a plate making device 20 that creates a printing plate according to the image data for plate-making.

The data processing device 10 edits the document image data expressed in the page description language, such as layout and color correction. Then, the data processing device 10 performs color separation processing for color separation of process colors and special colors, and halftone dot conversion processing for representing the gradation of each color by a set of halftone dots, thereby creating image data for plate making. , to the plate making apparatus 20 . The data processing device 10 includes a processor, a storage device, and a program that implements the functions of the data processing device 10 .

The data processing apparatus 10 includes a color separation processing unit 11 that performs color separation processing, a halftone dot condition setting unit 12 that sets conditions for halftone dot processing, a halftone dot processing unit 13 that performs halftone dot processing, and a transmission processing unit 14 for performing data transmission processing to the plate making apparatus 20 .

The color separation processing unit 11 performs color separation on the edited document image data for each process color, and applies UCR (under color removal) to portions where achromatic colors are reproduced in overlapping portions of each color. Process colors refer to ink colors used for printing, and may be, for example, four colors of cyan, magenta, yellow, and black, seven colors of red, green, and blue, and eight colors of white W. . The color separation processing unit 11 creates color separation image data, which is image data for each color extracted by color separation of the document image data.

The halftone dot setting unit 12 sets halftone dot conditions, which are the conditions for halftoning the color-separated image data created by the color separation processing unit 11 . Halftone dot conditions are set for each color-separated image data. The halftone dot conditions include halftone dot shapes, halftone dot area ratios, screen rulings, and screen angles for each color, as well as conditions related to a screening method.

The plate-making system 1 creates a printing plate capable of expressing colors other than the colors extracted by color separation by overprinting each color of ink extracted by color separation. At this time, the plate-making system 1 can produce a printing plate that can be overprinted using a cut-out method for each color extracted by color separation.

In the cutout method, out of the two colors to be overprinted, a cutout halftone dot is formed in one of the colors on the side closer to the base of the printed material, and the position where this cutout halftone dot is formed is more dense than the other color. In this method, halftone dots of the other color farther from the base of the printed material are overprinted. The color in which the halftone dots are formed may be the color farther from the base of the printed material.

Next, I will explain the selection method using two colors. The extraction method using three colors will be described later. If the four colors of cyan, magenta, yellow, and black are used as process colors, the two colors to be overprinted in the knockout method are preferably two colors selected from cyan, magenta, and yellow. Alternatively, the two colors to be overprinted by the knockout method are one selected from cyan, magenta, and yellow when the seven colors of cyan, magenta, yellow, red, green, blue, and black are used as process colors. Two colors are preferred, one in color and one selected from among red, green and blue.

In the example of FIG. 2(a), magenta M is used as one color, cyan C is used as the other color, and magenta M and cyan C are overprinted by a cutout method. In FIG. 2(a), blank halftone dots are formed at portions where magenta M, one of the colors, overlaps with cyan C, the other color. In other words, the halftone dots of cyan C of the other color are set so as to be located in the portions where the blank halftone dots of magenta M of the one color are formed. In the knockout method, the ink of the other color is overprinted with the ink of the other color with as little contact as possible.

On the other hand, in the conventional plate making system, as shown in FIG. Printing plates for overprinting are often produced. The multiplication method is a method of overprinting without forming a blank halftone dot in any of the two colors to be overprinted. In the multiplication method, halftone dots of one of the two overprinted colors overlap at least part of the halftone dots of the other color, so that the ink of one color and the ink of the other color come into contact with each other. It is overprinted.

The halftone dot setting unit 12 sets the separation image for each of the two colors to be subjected to the stripping method as a condition for the stripping method, which is one of the halftone dot conditions. Specify data. Then, the halftone dot condition setting unit 12 sets halftone dot area ratios of one color and the other color for each pixel of the specified color separation image data. Details of setting contents of the halftone dot area ratios of the one color and the other color to be subjected to the selection method will be described later.

The halftone processing unit 13 halftones the color-separated image data created by the color separation processing unit 11 according to the halftone conditions set by the halftone condition setting unit 12 . The halftone image data is, for example, binary data such as 1-bit TIFF (Tagged Image File Format). This halftone image data is used as image data for plate making when the plate making apparatus 20 makes a printing plate. The halftone processing unit 13 may be configured by software RIP (Raster Image Processor) or the like.

The halftone dot processing unit 13 halftone dots each of the separated image data of one color and the other color, which are two colors to be subjected to the subtraction method. Dot under different conditions. Specifically, when the halftone processing unit 13 halftones the divided image data of one color, the halftone dot processing unit 13 converts the divided image data of one color into reversed image data obtained by reversing the density of one color. is created once, and the created inverted image data is halftone-dotted under negative conditions. The negative condition is a condition in which a pixel having a lower color density has a higher halftone dot area ratio. On the other hand, when the halftone dot processing unit 13 halftones the separated image data of the other color, the halftone dot processing unit 13 halftone dots the separated image data of the other color as it is under the positive condition. The positive condition is a condition in which a pixel with a higher color density has a higher halftone dot area ratio.

The transmission processing unit 14 performs processing for transmitting the image data that has been halftone-dotted by the halftone processing unit 13 to the plate making device 20 as image data for plate making.

The plate making device 20 makes a printing plate for each color according to the image data transmitted from the transmission processing unit 14 of the data processing device 10, that is, the image data halftone-dotted for each color. The plate making apparatus 20 is preferably an apparatus for making a printing plate by the above-described DLE method or LAMS method. The plate making device 20 performs laser engraving or exposure on a resin plate based on image data converted into dots for each color to form an image area and a non-image area, thereby producing a printing plate. can be done.

[Halftone dot conversion conditions for the selection method]
FIG. 3 is a diagram for explaining gaps A and bites B formed in one color and the other color that are objects of the punching-out method. One color is magenta M, and halftone dots are formed. The other color is cyan C, and cyan C halftone dots are formed at the positions of magenta M blank halftone dots. FIG. 4 is a diagram showing the relationship between the total value of the halftone dot area ratio of one color and the halftone dot area ratio of the other color and the dimension a of the gap A or the dimension b of the encroachment B. FIG.

The halftone dot condition setting unit 12 sets the halftone dot area ratio of one color and the other color when setting the halftone dot area ratio of one color and the other color to be subjected to the subtraction method. It is set based on the total value with the area ratio. Specifically, the halftone dot setting unit 12 assigns halftone dots of the other color to pixels for which the sum of the halftone dot area ratio of one color and the halftone dot area ratio of the other color is less than 100%. Setting is made so that a gap A is formed around the dot with respect to the halftone dot of one color. Furthermore, the halftone dot condition setting unit 12 shifts halftone dots of the other color to pixels where the sum of the halftone dot area ratio of one color and the halftone dot area ratio of the other color exceeds 100%. It is set so that a bite B that bites into the periphery of the halftone dot of the color blank is formed.

The cut-in B is such that the center position of the halftone dot of the other color substantially coincides with the center position of the portion where the blank halftone dot of the one color is formed, and the size of the halftone dot of the other color is the same as that of the one color. It is formed larger than the size of the part where the halftone dot of color blanking is formed. In the bite B, the upper and lower relationship of the overlapping of the inks of one color and the other color does not matter. Also, in the present embodiment, two colors are selected, but the gap A and the biting B may be formed in three or more colors. Also, the shape of the halftone dots is not limited to circles, and may be polygons or other shapes. The halftone dot area ratio is the ratio of the halftone dot area per unit area.
Indicates the degree of shade of color.

The example of FIG. 3(a) shows the case where the halftone dot area ratio of one color magenta M and the halftone dot area ratio of the other color cyan C are less than 100%. In this case, around halftone dots of cyan C of the other color, there is formed a gap A with dimension a from magenta M of the other color. The gap A is preferably formed all around the halftone dot. As a result, even if each color is out of register, the ink is less likely to come into contact with the ink and turbidity can be suppressed. The dimension a of the gap A may be a difference value obtained by subtracting the radius of the halftone dot of cyan C of the other color from the radius of the part where the blank of magenta M of one color is formed.

The example of FIG. 3(b) shows a case where the halftone dot area ratio of one color magenta M and the halftone dot area ratio of the other color cyan C exceed 100%. In this case, a cut-in B is formed in which the halftone dot of cyan C of the other color is cut into the halftone dot of magenta M of the one color by a dimension b. The encroachment B is preferably formed all around the halftone dot. As a result, even if each color is misregistered, the background is less likely to be exposed. The dimension b of the encroachment B may be a difference value obtained by subtracting the radius of the part where the magenta M blank is formed from the radius of the halftone dot of cyan C of the other color.

The halftone dot condition setting unit 12 appropriately sets the total value of the halftone dot area ratio of one color and the halftone dot area ratio of the other color, so that the dimension a of the gap A or the dimension b of the encroachment B can be controlled, and the shade of the color that is expressed by overprinting one color and the other can be controlled.

In FIG. 4 , the halftone dot area ratio of one color indicated on the vertical axis and the halftone dot area ratio of the other color indicated on the horizontal axis intersect, and the total value thereof is formed. The dimension a of the clearance A or the dimension b of the encroachment B is indicated. In FIG. 4, the numbers written in black on a white background indicate the dimension a of the gap A, and the numbers written in white on a dark gray background indicate the dimension b of the encroachment B. As shown in FIG. In FIG. 4, the number "0" written in black on a light gray background is printed in a state in which the gap A and the bite B are not formed, that is, one color and the other color are overprinted in a state of tucking. It is shown that. In addition, in FIG. 4, "Nose" written in black letters on a white background indicates that either one color or the other color is solid.

FIG. 4 shows the total value of the halftone dot area ratio of one color and the halftone dot area ratio of the other color when the screen ruling is 100 lpi (line per inch), and the dimension a of the gap A or the encroachment The relationship of B to dimension b is shown. In this case, when the halftone dot area ratio of one color is "90%" and the halftone dot area ratio of the other color is "40%", the bite B with the dimension b of "0.05 mm" It can be seen that they are formed. When the halftone dot area ratio of one color is "90%" and the halftone dot area ratio of the other color is "40%", the sum of these values is "130%". In addition, when the dimension b of the bite B increases, the contact area between one color and the other color increases, and the ink tends to become turbid. It is preferable to set the total value of the halftone dot area ratio of one color and the halftone dot area ratio of the other color so that the one color bites into the other color. Since the degree of turbidity of ink differs depending on the type of printing plate, this total value is set according to the type of printing plate.

The halftone dot condition setting unit 12 sets the total value of the halftone dot area ratio of one color and the halftone dot area ratio of the other color to 100 when the printing plate is a resin relief printing plate. % and 125% or less, and when the printing plate is a waterless lithographic plate, it is set to a value in the range of more than 100% and 150% or less. As a result, the halftone dot condition setting unit 12 sets the conditions related to the knockout method so that one color and the other color can be overprinted while suppressing the turbidity of the ink in the pixels forming the bite B. be able to.

Next, the selection method using three colors will be explained. The three colors to be overprinted in the knockout method are preferably colors that express the hue of the pixel color, and are preferably selected from process colors other than black K or white W. When the four colors of cyan C, magenta M, yellow Y and black K are used as process colors, the three colors of cyan C, magenta M and yellow Y are suitable. Alternatively, when the seven colors of cyan C, magenta M, yellow Y, red R, green G, blue B, and black K are used as process colors, at least one selected from cyan C, magenta M, and yellow Y It is preferable to include a color and at least one color selected from red R, green G and blue B. Also, by using inks of colors such as fluorescent colors and gold, which cannot be expressed by a combination of cyan C, magenta M, yellow Y, red R, green G, and blue B as process colors, the expressible color gamut can be expanded. can. Eight colors of cyan C, magenta M, yellow Y, red R, green G, blue B, black K, and white W may be used as process colors. Also, the number of colors to be combined is not limited to three, and three or more colors may be combined.

5 and 6 show examples in which three colors of cyan (C), magenta and yellow (Y) are combined.
As shown in FIGS. 5 and 6, in the case of the knockout method in which halftone dots of three colors are overprinted, the halftone dot condition setting unit 12 sets the halftone dot area ratio of each color to be subjected to the knockout method. , is set based on the sum of the halftone dot area ratios of each color.
That is, the halftone dot condition setting unit 12 sets halftone dots of each color so that the halftone dots of each color do not overlap each other in pixels for which the sum of the halftone dot area ratios of the respective colors is 100% or less. In particular, the halftone dot area ratio is set so as to form a gap around at least one halftone dot of each color for pixels where the sum of the halftone dot area ratios of each color is less than 100%. Further, the halftone dot condition setting unit 12 places halftone dots around the halftone dots of the other two colors for at least one of the pixels for which the total value of the halftone dot area ratios of the respective colors exceeds 100%. Set to form a biting bite.
The formation of gaps and bites is the same as in the two-color stripping of FIG. 3, and the two-color stripping of FIG. 3 is formed at the boundaries of the respective colors.

FIGS. 5(a) and 5(b) show examples in which the total value of halftone dot area ratios of the respective colors is less than 100%.
FIG. 5A shows an example in which the halftone dot area ratio of each color in each pixel is 10% for yellow Y, 30% for both magenta M and cyan C, and the total value of the halftone dot area ratio is 70%. there is In this case, gaps are formed between cyan C and magenta M and between magenta M and yellow Y, respectively.

In FIG. 5B, the halftone dot area ratio of each color in each pixel is 10% for yellow Y, 40% for magenta M, and 30% for cyan C, and the total value of the halftone dot area ratio is 80%. showing. In this case, a gap is formed between cyan (C) and magenta (M).

FIG. 5(c) shows an example in which the total value of the halftone dot area ratio of each color exceeds 100%. FIG. 5C shows an example in which yellow Y is 15%, magenta M is 40%, cyan C is 60%, and the total halftone dot area ratio is 115%. In this case, bites are formed between cyan C and magenta M and between magenta M and yellow Y, respectively.

In the examples of FIGS. 5(a) to 5(c), the halftone dots of each color are circular, and the halftone dots of each color are arranged so that pixels of one color contain another color. In addition, halftone dots of each color are arranged concentrically in the pixel.

Further, the halftone dots of each color do not necessarily have the same shape. For example, as shown in FIGS. The yellow Y can be circular (annular) with a circular opening, and the magenta M can be circular.

In FIG. 6A, the halftone dot area ratio of each color in each pixel is 30% for cyan C, 35% for yellow Y, and 35% for magenta M, and the total value of the halftone dot area ratio is 100%. showing. Therefore, cyan C, yellow Y, and magenta M are printed on top of each other without gaps.

In FIG. 6B, the halftone dot area ratio of each color in each pixel is 30% for cyan C, 30% for yellow Y, and 30% for magenta M, and the total value of the halftone dot area ratio is 90%. showing. Therefore, gaps are formed between cyan C and yellow Y and between yellow Y and magenta M, respectively.

In addition, as shown in FIGS. 7(a) to 7(c), for example, halftone dots of each color may be square-shaped with different sizes, and each color may be provided concentrically within a pixel (see FIG. 7(c)). 7(a)), making halftone dots of one color (e.g., cyan C) a square shape, and making the halftone dots of the other two colors (e.g., yellow Y and magenta M) a rectangular shape so that they fit side by side in the square shape. (Fig. 7(b), Fig. 7(c)).

White W or black K, or white W and black K may be multiplied with the pixels overprinted by the above-described at least three-color extraction method. That is, pixels obtained by subtracting three colors are multiplied by white W only, black K only, or white W and black K overprinted by a subtracting method. Also, at this time, it is preferable that halftone dots of white W or black K, or halftone dots of white W and black K are arranged at a screen angle different from halftone dots of the other three colors. In this way, by multiplying a pixel obtained by extracting three colors by white W only, black K only, or white W and black K, the reproducibility of the brightness of the pixel is improved. In addition, if the base material is a mirror surface such as metal, a transparent color can be reproduced without white W, and an opaque color can be reproduced with white. You can make it bigger.

As in the case of two-color extraction, the halftone dot condition setting unit 12 calculates the total value of the halftone dot area ratios of at least three colors to be extracted in the pixel forming the bite B when the printing plate is a resin letterpress. is set to a value in the range of more than 100% to 125% or less, and in the case of a waterless lithographic printing plate, the value is set to a value in the range of more than 100% to 150% or less. As a result, the halftone dot condition setting unit 12 can set the conditions related to the cutout method so that the three colors can be overprinted while suppressing the turbidity of the ink in the pixels forming the bite B. In addition, when white W or black K, or white W and black K are multiplied by at least three colors, the halftone dot area ratio of at least three colors and white W or black K, or white W and black K If the sum of the dot area ratios is within the range of 160% or less, the turbidity of the ink can be suppressed.

[Plate-making method using plate-making system]
FIG. 8 is a diagram showing the flow of a plate making method for making a printing plate using the plate making system 1 shown in FIG.

Steps S501 to S506 shown in FIG. 8 may be executed by the data processing device 10 based on an operation command from the user input via a user interface provided in the data processing device 10. Step S<b>507 shown in FIG. 8 may be performed by plate making apparatus 20 .

In step S501, the prepress system 1 receives manuscript image data in the data processing device 10.

In step S502, the prepress system 1 edits the received manuscript image data. The prepress system 1 edits the document image data by correcting the layout and correcting the color tone according to the printing area of the printing material.

In step S503, the plate making system 1 performs plate separation processing on the edited document image data. The plate-making system 1 color-separates the edited document image data for each process color, and creates color-separated image data for each color.

In step S504, the plate making system 1 performs halftone dot setting processing for setting halftone dot conditions for halftone dot processing of the color-separated image data created by the color separation process. In particular, the plate-making system 1 designates the separated image data for each of the three colors to be subjected to the matching method, and sets the halftone dot area ratio for each of the three colors for each pixel of the designated separated image data. do. At this time, the prepress system 1 sets the halftone dot area ratios of the three colors so that the gap A and the encroachment B are appropriately formed based on the total value of the halftone dot area ratios of the three colors.

In step S505, the plate-making system 1 halftones the color-separated image data created in the color separation process according to the halftone dot conditions set in the halftone dot setting process.

In step S506, the plate-making system 1 performs a transmission process of transmitting the image data that has been halftone-dotted by the halftone-dotting process from the data processing device 10 to the plate making device 20 as image data for plate-making.

In step S507, the plate making system 1 makes a printing plate for each color by the plate making device 20 according to the image data transmitted in the transmission process.

[Effect]
As described above, the plate making system 1 according to the present embodiment is a system for making a printing plate based on the knockout method. The plate-making system 1 according to the present embodiment is a plate-making method for producing a printing plate capable of expressing the color of each pixel by overprinting halftone dots of at least three process colors. In pixels with a total value of halftone dot area ratios of 100% or less, halftone dots of respective colors are formed at positions that do not overlap each other.

For this reason, the plate-making system 1 according to the present embodiment produces a printing plate that has high color reproducibility and is capable of suppressing ink turbidity due to suppression of contact between the inks of the halftone dots of each color. be able to.

In addition, the plate-making system 1 according to the present embodiment adds , create a gap A between halftone dots of the other color and the halftone dots of the other color, and for pixels where the total value exceeds 100%, replace the halftone dots of the other color with the halftone dots of the other color. A bite B that bites into the periphery of the halftone dot is formed.

Therefore, the plate-making system 1 according to the present embodiment can set the dimension a of the gap A or the encroachment only by appropriately setting the total value of the halftone dot area ratio of one color and the halftone dot area ratio of the other color. The dimension b of B can be controlled. Specifically, in the prepress system 1 according to this embodiment, the gap A is formed when the total value of the halftone dot area ratio is less than 100%, and when the total value of the halftone dot area ratio exceeds 100%, A bite B is formed. As a result, the plate-making system 1 according to the present embodiment has a larger allowable value for misregistration than in the case of making a printing plate by the conventional knockout method, and can make a printing plate that is easy to register. can. In addition, the plate-making system 1 according to the present embodiment suppresses contact between inks by the punching method. is easily concealed, a printing plate can be produced that has a wide reproducible color gamut and gives a feeling of high density even in flat tints. As a result, the plate-making system 1 according to the present embodiment can produce a printing plate having high color reproducibility as compared with the case of producing a printing plate by the multiplication method. Therefore, the plate-making system 1 according to the present embodiment can produce a printing plate with easy registration and high color reproducibility while suppressing turbidity of ink by a relatively simple method.

In addition, the plate-making system 1 according to the present embodiment has a wide reproducible color gamut and can produce a printing plate that gives a high sense of density even with a screen tint. is unnecessary, and a printing plate capable of reducing the amount of ink used can be produced.

In addition, in the plate-making system 1 according to the present embodiment, the problem of ink trapping does not occur as compared with the case of making a printing plate by the multiplication method. No need to manage. As a result, the plate making system 1 according to the present embodiment can produce printing plates relatively free from restrictions due to ink properties, and therefore can produce printing plates with a high degree of freedom.

Furthermore, in the plate-making system 1 according to the present embodiment, when the printing plate is a resin relief plate, the above-described total value of the pixels forming the bite B is set to a value within the range of more than 100% and 125% or less, and printing If the plate is a waterless lithographic plate, the above sum value for the pixels forming the encroachment B is set to a value within the range of more than 100% and less than or equal to 150%. As a result, the plate-making system 1 according to the present embodiment can further suppress ink turbidity in the pixels forming the encroachment B, facilitate registration, and produce a printing plate with high color reproducibility. can.

Furthermore, in the prepress system 1 according to the present embodiment, halftone dot image data of one color can be obtained by changing the gradation of one color in the separated image data of one color extracted by color separation of the document image data. It is created by halftone-dotting the reversed reversed image data under negative conditions. On the other hand, in the plate-making system 1 according to the present embodiment, halftone-dotted image data of the other color is used to halftone-dot the separated image data of the other color extracted by color separation of the document image data. Created by Therefore, in the plate-making system 1 according to the present embodiment, a printing plate can be produced by a relatively simple method in which a blank is formed in one color and overprinted with the other color. As a result, the plate-making system 1 according to the present embodiment can more easily produce a printing plate with easy registration and high color reproducibility while suppressing turbidity of the ink.

Furthermore, the plate making system 1 according to the present embodiment produces a printing plate using a two-piece can or a metal plate as a substrate to be printed. Since the printing surface of a two-piece can or metal plate is impermeable to ink, the conventional printing plate can facilitate registration while suppressing turbidity of the ink. This poses a greater challenge than in the case of printed matter. The plate-making system 1 according to the present embodiment produces a printing plate based on the punching method even if the object to be printed is a two-piece can or a metal plate, and determines the dimension a of the gap A or the dimension b of the bite B. Controllable. Therefore, the plate-making system 1 according to the present embodiment can suppress ink turbidity, facilitate registration, and provide a printing plate with high color reproducibility even if the substrate to be printed is a two-piece can or a metal plate. can be made.

Furthermore, can bodies printed using the plate-making system 1 according to the present embodiment have a wide reproducible color gamut, and a high sense of density can be obtained even with a plain tint, because the base color is easily concealed by the extraction method. printed by the method. As a result, the can body printed using the plate making system 1 according to the present embodiment can have high color reproducibility by a relatively simple method compared to the can body printed by the multiplication method. .

[Other embodiments]
In the above-described embodiment, the plate-making system 1 is a system for producing a printing plate using a can body such as a two-piece can or a metal plate as a substrate to be printed. The plate-making system 1 is not limited to this, and may be a system for producing a printing plate using a three-dimensional object having a substantially cylindrical shape such as a bottle, a bottle, or a cup as a printing object. Moreover, the plate-making system 1 may be a system for making a printing plate using a planar object such as paper, a label, a film or a sheet as an object to be printed. Moreover, the plate making system 1 may be a system for making a printing plate using a non-metallic material with low ink permeability, such as plastic or glass, as a substrate to be printed.

[others]
The above-described embodiments can apply each other's techniques to each other including the modified examples. The above-described embodiments do not limit the content of the present invention, and modifications can be made without departing from the scope of the claims.

The terms used in the above embodiments and claims should be interpreted as non-limiting terms. For example, the term "including" should be interpreted as "not limited to what is stated to include." The term "containing" should be interpreted as "not limited to what is stated to contain." The term "comprising" should be interpreted as "not limited to what is described as comprising". The term "having" should be interpreted as "not limited to what is described as having".

REFERENCE SIGNS LIST 1 plate making system 10 data processor 11 plate separation processing unit 12 halftone dot setting unit 13 halftone dot processing unit 14 transmission processing unit 20 plate making device 30 offset printing machine A clearance a dimension of clearance B bite b dimension of bite C Cyan M Magenta

Claims

A plate-making method for producing a printing plate capable of expressing the color of each pixel by overprinting halftone dots of at least three process colors,
In pixels where the sum of the halftone dot area ratios of the process colors is 100% or less, halftone dots are formed in positions where the halftone dots of the respective colors do not overlap each other, and the halftone dots of the process colors are overprinted. A plate-making method, wherein the printing plate is prepared based on a joining method.
forming a gap around at least one halftone dot of each color of the process color in pixels where the sum of the halftone dot area ratios of the process colors is less than 100%;
2. The plate making method according to claim 1, wherein at least one halftone dot of each color of said process colors is formed to bite into the periphery of each halftone dot in pixels where said total value exceeds 100%.
The printing plate is a resin letterpress,
3. The plate making method according to claim 2, wherein the range of said total value in pixels forming said encroachment is more than 100% and less than or equal to 125%.
The printing plate is a waterless lithographic plate,
3. The plate making method according to claim 2, wherein the range of said total value in pixels forming said encroachment is more than 100% and less than or equal to 150%.
The prepress method according to any one of claims 1 to 4, wherein halftone dots of each color are arranged so that pixels of one color contain another color.
The plate making method according to any one of claims 1 to 5, wherein halftone dots of each color are arranged concentrically in the pixel.
The plate making method according to any one of claims 1 to 6, wherein the material to be printed of the printing plate is a substantially cylindrical can body or a metal plate.
The platemaking method according to any one of claims 1 to 7, wherein the pixel is further multiplied by black only, white only, or black and white.
The platemaking method according to claim 8, wherein said black and white are obtained by combining black and white by said combining method.
The prepress method according to claim 8 or 9, wherein the black only, white only, or black and white halftone dots are arranged at different screen angles than the at least three color halftone dots.
A plate-making system for producing a printing plate capable of expressing the color of each pixel by overprinting halftone dots of at least three process colors,
In pixels where the sum of the halftone dot area ratios of the process colors is 100% or less, halftone dots are formed in positions where the halftone dots of the respective colors do not overlap each other, and the halftone dots of the process colors are overprinted. A plate-making system for making the printing plate based on a matching method.
A can body printed to express the color of each pixel by overprinting halftone dots of at least three process colors,
In pixels where the sum of the halftone dot area ratios of the process colors is 100% or less, halftone dots are formed at positions where the halftone dots of the colors do not overlap each other, and the halftone dots of the process colors are overprinted. A can body with printing based on the matching method.