A digital proofing method for gravure printing of multi-channel images

Abstract

The present invention relates to a multi-channel image gravure digital proofing method, comprising: performing light and dark contrast matching on a printer and a gravure plate, selecting a multi-level grayscale scale pattern, using roller printing to obtain a grayscale scale printed pattern, using a printer to print the grayscale scale printed pattern, respectively measuring the color density of each grayscale level in the two patterns, and adjusting the print density of the printer when printing the multi-level grayscale scale pattern according to the measurement results; performing color overlay matching on the printer and the gravure plate, selecting a multi-printing channel pattern, performing sample color matching, using roller printing to obtain a multi-printing channel printed pattern, using a printer to print with the same color matching to obtain a multi-printing channel printed pattern, comparing the color overlay difference between the two patterns and adjusting the printing grayscale of the printer; and using the matched printer to print the multi-channel image to be printed, thereby completing proofing. The present invention can ensure that the pattern printed by the printer directly reflects the result of gravure printing, thereby achieving rapid proofing.

Description

Technical Field

[0001] The invention belongs to the technical field of gravure printing, and in particular relates to a gravure digital proofing method for multi-channel images. Background Art

[0002] Gravure printing is a direct printing technique with advantages such as stable print quality and high printing speed. Gravure printing involves directly imprinting the ink contained in the intaglio pits onto the substrate surface. The intensity of the printed pattern is determined by the size and depth of the pits. Deeper pits contain more ink, leaving a thicker ink layer on the substrate after imprinting; shallower pits contain less ink, leaving a thinner ink layer on the substrate after imprinting. During gravure printing, pits corresponding to the pattern to be printed are typically engraved on a roller. During printing, ink is filled into the pits, and the ink on the roller surface is scraped off with a doctor blade. The roller and substrate are in contact under a certain pressure, transferring the ink from the pits to the substrate, completing the printing process.

[0003] Before carrying out formal gravure printing, it is usually necessary to carry out proofing to obtain a printed sample, thereby confirming whether the printing effect is qualified, while also reducing production costs. When the printed pattern is proofed, the method of digital proofing can usually be adopted, i.e., a printer is adopted to print the printed pattern on printing paper, and the printer can be controlled by control software such as EFI, GMG, AVA. At present, CMYK printing mode is usually adopted to carry out the matching of digital proofing and terminal printed product, and control software has more settings and support for the proofing reduction of CMYK printing mode, but for the gravure printing of some special industries, it is still necessary to use multi-channel printing mode, and multi-channel printing mode is more intuitive to the adjustment of pattern, and some pattern details can be avoided from being lost. However, the grayscale increment under the different meshes that the current control software controls the printer to directly print out and the identical grayscale mesh obtained by engraving with an electric engraving machine cannot be matched, resulting in mismatch between a printed draft and a printed draft, causing the sample printed to be unable to accurately reflect the effect of final gravure printing. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for gravure digital proofing of multi-channel images.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for digital gravure proofing of a multi-channel image comprises the following steps:

[0007] S1: Matching the contrast between the printer and the gravure plate, including:

[0008] (1) Select a multi-level grayscale scale pattern, engrave it onto a roller, use the roller to print the multi-level grayscale scale pattern on the surface of the substrate to obtain a grayscale scale printing pattern, use a printer to print the multi-level grayscale scale pattern on printing paper to obtain a grayscale scale printing pattern,

[0009] (2) Measure the color density D of each gray level in the grayscale printed pattern 1n , measure the color density D of each gray level in the gray scale print pattern 2n , according to the color density measurement results, the printing density of the multi-level grayscale scale pattern printed by the printer is adjusted to complete the light and dark contrast matching;

[0010] S2: Color overlay matching between printer and gravure, including:

[0011] (1) Select a multi-printing channel pattern, engrave it onto a roller, perform sample color matching, use the roller to print the multi-printing channel pattern on the surface of the substrate to obtain a multi-printing channel printing pattern, use a printer to print the multi-printing channel pattern on printing paper with the same color matching to obtain a multi-printing channel printing pattern,

[0012] (2) comparing the color overlay differences between the multi-printing channel printing pattern and the multi-printing channel printing pattern, adjusting the printing grayscale of the printer according to the comparison result, and completing the color overlay matching;

[0013] S3: Print the multi-channel image to be printed using the matched printer to complete the proofing process.

[0014] Preferably, in step S1 (1), the total number of levels of the multi-level grayscale scale pattern is n, and n is 10-25.

[0015] Further preferably, the total number n of levels of the multi-level grayscale scale pattern is 20.

[0016] Preferably, in steps S1(1) and S2(1), electronic engraving or laser engraving is used when engraving the multi-level grayscale pattern and the multi-printing channel pattern.

[0017] Preferably, in step S1(2), when measuring color density, the following steps are included: an irradiation light source is focused by a focusing lens to form a measurement light and irradiates the measurement light onto the pattern to be measured, part of the measurement light is absorbed by the pattern to be measured, and part of the measurement light is reflected by the pattern to be measured to form a reflected light, the reflected light at a set angle to the measurement light is collected by a collecting lens, and the reflected light is transmitted to a receiver, the receiver converts the received light amount into electrical quantity to obtain the measurement electrical quantity, and compares the measurement electrical quantity with the reference electrical quantity, and the difference between the two is the color density of the pattern to be measured.

[0018] Further preferably, the set angle between the reflected light collected by the collecting lens and the measuring light is 30-60°.

[0019] More preferably, the set angle between the reflected light collected by the collecting lens and the measuring light is 45°.

[0020] Further preferably, the receiver is a photodiode.

[0021] Further preferably, the reference electrical quantity is the electrical quantity measured when the pattern to be measured is white.

[0022] Preferably, in steps S1(1) and S2(1), EFI software is used to control the printer to print.

[0023] Preferably, in step S1(2), EFI software is used to adjust the printing density of the printer when printing the multi-level grayscale scale pattern.

[0024] Preferably, in step S1(2), the printing density of the printer when printing the multi-level grayscale scale pattern is adjusted according to the color density measurement result, so that the color density D of each grayscale in the grayscale scale printing pattern is 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n All are within the set range K.

[0025] Further preferably, the color density D of each gray level in the gray scale print pattern is calculated. 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n , if the difference d n Within the set range K, the matching process is completed. If the difference d n If it is not within the set range K, adjust the printing density of the printer when printing the multi-level grayscale scale pattern, then print the grayscale scale pattern, and measure the color density D of each grayscale in the grayscale scale pattern. 2n , calculate the color density D of each gray level in the gray scale print pattern again 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n , until the difference d n All are within the set range K.

[0026] More preferably, the setting range K is -0.1 to 0.1.

[0027] Preferably, in step S2 (2), if the color of the multi-printing channel print pattern is darker than the color of the multi-printing channel print pattern, the printing grayscale of the printer is reduced proportionally so that the color of the multi-printing channel print pattern matches the color of the multi-printing channel print pattern.

[0028] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0029] The present invention matches the light and dark contrast and color overlay of the printer and the gravure plate, so that the pattern printed by the printer can directly reflect the result of gravure printing, which is convenient for judging the color separation printing result, realizes rapid proofing, reduces the printing proofing process, saves time, improves work efficiency, reduces costs, has a simple process, is easy to operate, and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Attachment Figure 1 It is a flow chart of the gravure digital proofing method of the multi-channel image of the present invention;

[0031] Attachment Figure 2 Schematic diagram of the grayscale ruler printing pattern of the present invention;

[0032] Attachment Figure 3 A schematic diagram of a grayscale ruler printing pattern before light and dark contrast matching according to the present invention;

[0033] Attachment Figure 4 This is a schematic diagram of a grayscale ruler printing pattern after light and dark contrast matching according to the present invention. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] A method for digital gravure proofing of multi-channel images, such as Figure 1As shown, the following steps are included:

[0037] S1: Matching the contrast between the printer and the gravure plate, including:

[0038] (1) Select a multi-level grayscale scale pattern, use a roller to print the multi-level grayscale scale pattern on the surface of the substrate, and use a printer to print the multi-level grayscale scale pattern on printing paper. Specifically:

[0039] The total number of steps of the multi-step grayscale scale pattern is n, and n is preferably 10 to 25. In this embodiment, the total number of steps n of the multi-step grayscale scale pattern is 20; the multi-step grayscale scale pattern is engraved on the roller, specifically by electronic engraving or laser engraving, but not limited to this embodiment; black ink is used and the multi-step grayscale scale pattern is printed on the surface of the substrate using a roller to obtain a grayscale scale printed pattern, such as Figure 2 As shown; use EFI software to control the printer to print, print the multi-level grayscale scale pattern on the printing paper, and obtain the grayscale scale print pattern, as shown Figure 3 shown.

[0040] (2) Measure the color density D of each gray level in the grayscale printed pattern 1n , measure the color density D of each gray level in the gray scale print pattern 2n , when measuring color density, the specific steps include:

[0041] A stable light source is controlled to focus through a focusing lens to form a measuring light beam. The measuring light beam is then irradiated onto the pattern to be measured. At this point, part of the measuring light beam is absorbed by the pattern to be measured, while another part of the measuring light beam is reflected by the pattern to be measured to form a reflected light beam. The reflected light beam is collected by a collecting lens at a set angle to the measuring light beam. The set angle between the reflected light beam collected by the collecting lens and the measuring light beam can be 30 to 60 degrees, preferably 45 degrees. The reflected light beam is then transmitted to a receiver, which can be a photodiode. The receiver converts the amount of light received into an electrical quantity, thereby obtaining a measured electrical quantity. The measured electrical quantity is compared with a reference electrical quantity. The reference electrical quantity is the electrical quantity measured through the above steps when the pattern to be measured is white. The reference electrical quantity measurement process is not further described here. The difference between the measured electrical quantity and the reference electrical quantity is the color density of the pattern to be measured.

[0042] By measuring the grayscale scale printing pattern and the grayscale scale printing pattern respectively through the above steps, the color density D of each gray level in the grayscale scale printing pattern can be obtained. 1n , that is, D 11 、D 12 、···、D 1n , the color density D of each gray level in the gray scale print pattern 2n , that is, D 21 、D22 、···、D 2n .

[0043] (3) According to the color density measurement results, the printing density of the printer when printing the multi-level grayscale scale pattern is adjusted so that the color density D of each grayscale in the grayscale scale printing pattern is 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n All are within the set range K. Specifically:

[0044] Calculate the color density D of each gray level in the grayscale print pattern 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n , that is, D 21 -D 11 =d1、D 22 -D 12 =d2、···、D 2n -D 1n =d n ; Determine the difference d n Whether it is within the set range K, that is, judging d1, d2, ···, d n Are they both within the set range K, the setting range K is -0.1 to 0.1; if the difference d n Within the set range K, the matching process is completed; if the difference d n If it is not within the set range K, use EFI software to adjust the print density when the printer prints the multi-level grayscale scale pattern. After the adjustment is completed, print again to obtain a new grayscale scale print pattern, and measure the color density D of each grayscale in the new grayscale scale print pattern. 2n , calculate the color density D of each gray level in the gray scale print pattern again 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n , and again determine the difference d n Is it within the set range K? Repeat the adjustment steps until the difference d n If both are within the set range K, the matching process is completed; Figure 4 The figure shows the grayscale scale pattern printed by the printer after the matching is completed. Figure 2 The grayscale scale printing patterns are basically the same.

[0045] S2: Color overlay matching between printer and gravure, including:

[0046] (1) Select a multi-printing channel pattern, use a roller to print the multi-printing channel pattern on the surface of the substrate, and use a printer to print the multi-printing channel pattern on printing paper. Specifically:

[0047] The multi-printing channel pattern is engraved on a roller, specifically by electronic engraving or laser engraving, but not limited to this embodiment; a printing sample is matched in color, and the multi-printing channel pattern is printed on a substrate surface using a roller to obtain a multi-printing channel printed pattern; the multi-printing channel pattern is printed on printing paper with the same color matching using EFI software to obtain a grayscale scale printed pattern;

[0048] (2) Compare the color overlay differences between the multi-printing channel printing pattern and the multi-printing channel printing pattern, and adjust the printing grayscale of the printer according to the comparison results. Specifically: if the color of the multi-printing channel printing pattern is darker than the color of the multi-printing channel printing pattern, it means that the ink of the printer is darker than the ink of the gravure at the same grayscale, then reduce the printing grayscale of the printer in proportion so that the color of the multi-printing channel printing pattern matches the color of the multi-printing channel printing pattern.

[0049] S3: After steps S1 and S2, the light and dark contrast matching and color overlay matching of the printer and the gravure are completed. At this time, the printer can be used to print any multi-channel image to complete the proofing process. The high degree of matching between the printer's printout and the gravure printing's printout makes it easy to check the printing results and achieves fast proofing.

[0050] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for digital gravure proofing of a multi-channel image, characterized by: The steps include: S1: Matching the contrast between the printer and the gravure plate, including: (1) Select a multi-level grayscale scale pattern, engrave it onto a roller, use the roller to print the multi-level grayscale scale pattern on the surface of the substrate to obtain a grayscale scale printing pattern, use a printer to print the multi-level grayscale scale pattern on printing paper to obtain a grayscale scale printing pattern, (2) Measure the color density D of each gray level in the grayscale printed pattern 1n , measure the color density D of each gray level in the gray scale print pattern 2n , according to the color density measurement results, the printing density of the multi-level grayscale scale pattern printed by the printer is adjusted to complete the light and dark contrast matching; S2: Color overlay matching between printer and gravure, including: (1) Select a multi-printing channel pattern, engrave it onto a roller, perform sample color matching, use the roller to print the multi-printing channel pattern on the surface of the substrate to obtain a multi-printing channel printing pattern, use a printer to print the multi-printing channel pattern on printing paper with the same color matching to obtain a multi-printing channel printing pattern, (2) comparing the color overlay differences between the multi-printing channel printing pattern and the multi-printing channel printing pattern, adjusting the printing grayscale of the printer according to the comparison result, and completing the color overlay matching; S3: Print the multi-channel image to be printed using the matched printer to complete the proofing process.

2. The method for gravure digital proofing of a multi-channel image according to claim 1, characterized in that: In step S1(1), the total number of levels of the multi-level grayscale scale pattern is n, and n is 10-25.

3. The method for digital gravure proofing of a multi-channel image according to claim 1, wherein: In steps S1(1) and S2(1), electronic engraving or laser engraving is used when engraving the multi-level grayscale scale pattern and the multi-printing channel pattern.

4. The method for digital gravure proofing of a multi-channel image according to claim 1, wherein: In step S1(2), when measuring color density, the following steps are included: an irradiation light source is focused by a focusing lens to form a measurement light and irradiates the measurement light onto the pattern to be measured, part of the measurement light is absorbed by the pattern to be measured, and part of the measurement light is reflected by the pattern to be measured to form a reflected light, the reflected light at a set angle to the measurement light is collected by a collecting lens, and the reflected light is transmitted to a receiver, the receiver converts the received light amount into electrical quantity to obtain the measurement electrical quantity, and compares the measurement electrical quantity with the reference electrical quantity, and the difference between the two is the color density of the pattern to be measured.

5. The method for digital gravure proofing of a multi-channel image according to claim 4, characterized in that: The set angle between the reflected light collected by the collecting lens and the measurement light is 30 to 60 degrees.

6. The method for digital gravure proofing of a multi-channel image according to claim 1, wherein: In steps S1(1) and S2(1), the EFI software is used to control the printer to print; in step S1(2), the EFI software is used to adjust the printing density of the printer when printing a multi-level grayscale scale pattern.

7. The method for digital gravure proofing of a multi-channel image according to claim 1, wherein: In step S1(2), the printing density of the printer when printing the multi-level grayscale pattern is adjusted according to the color density measurement result, so that the color density D of each gray level in the grayscale pattern is 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n All are within the set range K.

8. The method for digital gravure proofing of a multi-channel image according to claim 7, characterized in that: Calculate the color density D of each gray level in the grayscale print pattern 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n , if the difference d n Within the set range K, the matching process is completed. If the difference d n If it is not within the set range K, adjust the printing density of the printer when printing the multi-level grayscale scale pattern, then print the grayscale scale pattern, and measure the color density D of each grayscale in the grayscale scale pattern. 2n , calculate the color density D of each gray level in the gray scale print pattern again 2n The color density D of each gray level in the gray scale printing pattern 1n The difference d n , until the difference d n All are within the set range K.

9. The method for digital gravure proofing of a multi-channel image according to claim 7, wherein: The setting range of K is -0.1 to 0.

1.

10. The method for digital gravure proofing of a multi-channel image according to claim 1, characterized in that: In step S2 (2), if the color of the multi-printing channel print pattern is darker than the color of the multi-printing channel print pattern, the printing grayscale of the printer is reduced in proportion so that the color of the multi-printing channel print pattern matches the color of the multi-printing channel print pattern.

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