CN114475029A - High-screen printing method - Google Patents
High-screen printing method Download PDFInfo
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- CN114475029A CN114475029A CN202011155967.9A CN202011155967A CN114475029A CN 114475029 A CN114475029 A CN 114475029A CN 202011155967 A CN202011155967 A CN 202011155967A CN 114475029 A CN114475029 A CN 114475029A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M1/00—Inking and printing with a printer's forme
- B41M1/06—Lithographic printing
Abstract
The invention belongs to the technical field of printing, and particularly relates to a high-screen printing method, which comprises the following steps: importing a color digital image manuscript, and carrying out color separation on the color digital image to obtain four single-channel gray level images of CMYK; traversing the single-channel gray image, acquiring the color value distribution condition of the single-channel gray image, and establishing a gray image color value distribution contour line; setting the mesh points as mixed screening, wherein the mixed screening comprises frequency modulation screening and amplitude modulation screening; selecting frequency modulation mesh points or amplitude modulation mesh points according to different color densities of each image; printing pressure is debugged, high-hardness rubber cloth and a gasket are replaced, the liquid feeding amount of fountain solution is adjusted, the flow speed of cooling water of the printing machine is accelerated, and printing is produced. The method of the invention enables the number of the printed screen lines to reach more than 300 lines, eliminates the defect that the screen points can be seen by naked eyes, can realize stepless smooth tone-changing ultrafine particles, greatly improves the definition and eliminates ripple patterns or rose patterns.
Description
Technical Field
The invention belongs to the technical field of printing, and particularly relates to a high-screen printing method.
Background
Amplitude modulation screening is the most widely used printing screening method at present, and is characterized in that the area rate of the screen dots is determined by the gray value of image pixels, the number of the screen lines is determined by the number of the unit length, the small dots are regularly diffused and intensively distributed from the center to the periphery to form the screen dots, and the shape and the screening angle of the screen dots are determined by the diffusion rule. The distance between the net points in the horizontal direction and the vertical direction is equal.
The amplitude modulation screening technology is mature, particularly, the screen has perfect performance on the position of the intermediate tone, has low requirements on equipment environment and printing conditions, and is widely applied to prepress treatment. However, the am screening technique still has some inevitable drawbacks: the distance between amplitude modulation and screening dots is fixed, and fine layers of images cannot be represented at the positions of bright tones and dark tones, so that high-fidelity printing cannot be performed; the angles of the four-color screening are different, and moire patterns and inevitable fine rose spots are easy to appear when the colors are copied; in the process of increasing the gray value of the pixel, as the area of amplitude-modulated screening dots is increased, the dots are contacted with each other finally, and tone level jump is generated; in order to avoid moire, amplitude modulation screening can only take four screening angles of 15 degrees, 45 degrees, 75 degrees and 90 degrees, and multicolor printing of more than four colors is not supported.
The frequency modulation screening technology is one of the main development directions of the current screen dot technology, the size of the frequency modulation screening screen dots is basically unchanged, the screen dots are irregularly distributed, different spatial positions exist along with different screening algorithms, the screen dot spacing is unequal, the screen dot distribution density (frequency and the number of the screen dots) shows a gradation level, the concepts of screen lines and screening angles do not exist, and the screen dot diameter is usually used for distinguishing. Compared with amplitude modulation screening, frequency modulation screening can reproduce more image details, can solve the problems of saw teeth and breakage of thin lines, and generation of moire and rose spots due to screen collision of images with textures and grids, does not need to consider the angles of screen dots, can realize the effect of high-line-number printing, and can be used for high-fidelity printing. But also has the following defects: the mesh points have granular feeling due to equal size, the position of each group of mesh points is difficult to control in the middle adjusting position, and particularly, ink spots can occur during the flat screen; in the whole production process, the latitude is smaller than that of an amplitude modulation screening technology, so that a more detailed process control and monitoring technology is required; the size of the dots is too small, the difficulty of imaging the dots on a printing plate is high, the requirements on equipment and environment are high, so that many printing machines cannot correctly finish dot reproduction, and the dot expansion is serious and is difficult to control.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a high-screen printing method based on a screen dot color control process, which enables the number of printed screen lines to reach more than 300 lines, eliminates the defect that the screen dots can be seen by naked eyes, can realize stepless smooth tone-changing ultrafine particles, greatly improves the definition and eliminates a ripple pattern or a rose pattern; the method can restore the color to the maximum in some dark color works with bright color and high saturation, and highlight the detail level and the like, thereby meeting the aesthetic requirements of modern people.
The technical scheme provided by the invention is as follows:
a high-screen printing method, comprising the steps of:
importing a color digital image manuscript, and carrying out color separation on the color digital image to obtain four single-channel gray level images of CMYK;
traversing the single-channel gray image, acquiring the color value distribution condition of the single-channel gray image, and establishing a gray image color value distribution contour line;
setting the mesh points as mixed screening, wherein the mixed screening comprises frequency modulation screening and amplitude modulation screening;
selecting frequency modulation mesh points or amplitude modulation mesh points according to different color densities of each image;
printing pressure is debugged, high-hardness rubber cloth and a gasket are replaced, the liquid feeding amount of fountain solution is adjusted, the flow speed of cooling water of the printing machine is accelerated, and printing is produced.
Further, the method for establishing the color value distribution contour line of the gray scale image specifically comprises the following steps:
establishing a contour line for the first time; establishing a primary contour line according to three levels of 0-10% of a bright tone area, 10-90% of a middle area and 90-100% of a dark tone area, and simply separating the bright tone area, the middle area and the dark tone area of the single-channel gray-scale image;
establishing a secondary contour line: and establishing secondary contour lines for the bright tone area and the dark tone area according to the tone change condition and the 1% gray level change level, and carrying out secondary division on the gray level change of the bright tone area and the dark tone area.
Furthermore, frequency modulation mesh points are adopted to express 10-90% of middle area, amplitude modulation mesh points are adopted to express 0-10% of bright area and 90-100% of dark area, and the conversion point of amplitude modulation and frequency modulation changes along with the change of mesh line number.
Furthermore, 2-3 small dots are combined into a larger dot in 0-10% of the bright part.
Further, the distribution of the mesh points is optimized on the principle of no overlap and no large gaps.
Furthermore, an anilox roller of the printing machine is provided with a trapezoidal section diagonal line type mesh opening; the ink carrying capacity of the anilox roller is 8-9cm3/m2。
Further, the printing pressure is adjusted to 75-90% of the normal printing pressure when printing.
Further, during printing, the hardness of the rubber blanket is 80-85 degrees Shore A, the surface smoothness is 0.9-1.0um, the elongation is less than 1.8%, and the thickness reduction rate during elongation is less than 1.8%.
Furthermore, the maximum density Dmax of the four-color printed matter is 2.0-2.1, and the density value of the four colors of the ink is C1.40-1.45M1.45-1.50Y0.95K 1.50-1.90.
Further, selecting high-quality four-color ink with high viscosity as the ink; the printing ink comprises, by weight, 42-45 parts of a main resin, 36-38 parts of a reactive diluent, 24-26 parts of a coloring material, 8-12 parts of a photoinitiator and 2-4 parts of an auxiliary agent.
Advantageous effects
The technical scheme of the invention adopts a mixed screening technology, the mixed screening integrates two screening technologies of amplitude screening and frequency modulation screening, combines the advantages of the two screening technologies, overcomes the respective defects, changes the expression details or brightness of the traditional frequency modulation screening, and the amplitude modulation screening shows a flat screen or a middle tone, realizes different mesh point sizes, positions and numbers and has alternate frequency modulation/amplitude modulation; the process method realizes high-screen printing on the premise of not changing the existing printing conditions and not increasing the cost. The printed matter image is very fine and smooth, the screen can not be seen basically or completely, the net collision of a real object is basically eliminated, and the printed matter with the spot color effect can be printed by using four colors.
The method is based on Sublima, adopts frequency modulation dots to express a middle tone (10-90%), amplitude modulation dots to express a bright tone (0-10%) and a dark tone (90-100%), and the conversion point of amplitude modulation and frequency modulation changes along with the change of the number of the network lines; and optimizing the transition from amplitude modulation to frequency modulation based on a certain algorithm, wherein when the amplitude modulation is transited to the frequency modulation, random points of the frequency modulation continue the angle of amplitude modulation points, and transition traces from the amplitude modulation to the frequency modulation are completely eliminated.
The method optimizes the process, and always enables the minimum screen dots to meet the process requirements of common printing when the transition from the middle tone to the bright tone and the dark tone is realized, so that the production cost can be greatly reduced. When Sublima dots of each number of the screen lines are output, the equipment only needs to adopt the set output precision, and the high-screen-line printing plate is produced on the premise of not reducing the output efficiency.
The technical scheme of the invention enables the number of the printed screen lines to reach more than 300 lines, eliminates the defect that the screen points can be seen by naked eyes, can realize stepless smooth tone-changing ultrafine particles, greatly improves the definition and eliminates ripple patterns or rose patterns; the method can restore the color to the maximum in some dark color works with bright color and high saturation, and highlight the detail level and the like, and meets the aesthetic requirements of modern people, so that the method has great significance and market value in the packaging industry.
Detailed Description
The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto.
Example 1
A high-screen printing method based on a screen dot color control process comprises the following steps:
importing a color digital image manuscript, and carrying out color separation on the color digital image to obtain four single-channel gray level images of CMYK;
traversing the single-channel gray image, acquiring the color value distribution condition of the single-channel gray image, and establishing a gray image color value distribution contour line;
the method specifically comprises the following steps:
establishing a contour line for the first time; establishing a primary contour line according to three levels of 0-10% of a bright tone area, 10-90% of a middle area and 90-100% of a dark tone area, and simply separating the bright tone area, the middle area and the dark tone area of the single-channel gray-scale image;
establishing a secondary contour line: and establishing secondary contour lines for the bright tone area and the dark tone area according to the tone change condition and the 1% gray level change level, and carrying out secondary division on the gray level change of the bright tone area and the dark tone area.
Setting the mesh points as mixed screening, wherein the mixed screening comprises frequency modulation screening and amplitude modulation screening;
selecting frequency modulation mesh points or amplitude modulation mesh points according to different color densities of each image; the distribution of the mesh points is optimized according to the principle that no overlapping and no large interval are formed;
specifically, frequency modulation dots are adopted to express a middle tone (10-90%), amplitude modulation dots are adopted to express a bright tone (0-10%) and a dark tone (90-100%), and the conversion points of amplitude modulation and frequency modulation change along with the change of the number of the network lines;
combining 2-3 small dots into a larger dot in 0-10% of the bright part;
when the amplitude modulation is transited to the frequency modulation, the random mesh points of the frequency modulation continue the angles of the amplitude modulation mesh points, so that transition traces are completely eliminated, and the mesh points of the two frequencies are skillfully fused.
Printing pressure is debugged, high-hardness rubber cloth and a gasket are replaced, the liquid feeding amount of fountain solution is adjusted, the flow speed of cooling water of the printing machine is accelerated, and printing is produced.
An anilox roller of the printing machine is provided with a trapezoidal section diagonal line type mesh; the ink carrying capacity of the anilox roller is 8-9cm3/m2。
Selecting high-quality four-color ink with high viscosity as the ink; the printing ink comprises, by weight, 42-45 parts of a main resin, 36-38 parts of a reactive diluent, 24-26 parts of a coloring material, 8-12 parts of a photoinitiator and 2-4 parts of an auxiliary agent.
The output device resolution O satisfies O9600 dpi.
The final output networking line number N is 800-;
the maximum density Dmax of the four-color printed matter is 2.0-2.1, and the density value of the four colors of the ink is C1.40-1.45M1.45-1.50Y0.95K 1.50-1.90;
during printing, the printing pressure is adjusted to 75-90% of the normal printing pressure.
When printing, the hardness of the rubber blanket is 80-85 degrees Shore A, the surface smoothness is 0.9-1.0um, the elongation is less than 1.8 percent, and the thickness reduction rate during the elongation is less than 1.8 percent.
The technical scheme of the invention adopts a mixed screening technology, the mixed screening integrates two screening technologies of amplitude screening and frequency modulation screening, combines the advantages of the two screening technologies, overcomes the respective defects, changes the expression details or brightness of the traditional frequency modulation screening, and the amplitude modulation screening shows a flat screen or a middle tone, realizes different mesh point sizes, positions and numbers and has alternate frequency modulation/amplitude modulation; the process method realizes high-screen printing on the premise of not changing the existing printing conditions and not increasing the cost. The printed matter image is very fine and smooth, the screen can not be seen basically or completely, the net collision of a real object is basically eliminated, and the printed matter with the spot color effect can be printed by using four colors.
The method is based on Sublima, adopts frequency modulation dots to express a middle tone (10-90%), amplitude modulation dots to express a bright tone (0-10%) and a dark tone (90-100%), and the conversion point of amplitude modulation and frequency modulation changes along with the change of the number of the network lines; and optimizing the transition from amplitude modulation to frequency modulation based on a certain algorithm, wherein when the amplitude modulation is transited to the frequency modulation, random points of the frequency modulation continue the angle of amplitude modulation points, and transition traces from the amplitude modulation to the frequency modulation are completely eliminated.
The method optimizes the process, and always enables the minimum screen dots to meet the process requirements of common printing when the transition from the middle tone to the bright tone and the dark tone is realized, so that the production cost can be greatly reduced. When Sublima dots of each number of the screen lines are output, the equipment only needs to adopt the set output precision, and the high-screen-line printing plate is produced on the premise of not reducing the output efficiency.
The technical scheme of the invention enables the number of the printed screen lines to reach more than 300 lines, eliminates the defect that the screen points can be seen by naked eyes, can realize stepless smooth tone-changing ultrafine particles, greatly improves the definition and eliminates ripple patterns or rose patterns; the method can restore the color to the maximum in some dark color works with bright color and high saturation, and highlight the detail level and the like, and meets the aesthetic requirements of modern people, so that the method has great significance and market value in the packaging industry.
The above description is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that appropriate modifications and optimization can be made based on the technical principle of the present invention, and these modifications and optimization should also be regarded as the protection scope of the present invention.
Claims (10)
1. A high-screen printing method is characterized by comprising the following steps:
importing a color digital image manuscript, and carrying out color separation on the color digital image to obtain four single-channel gray level images of CMYK;
traversing the single-channel gray image, acquiring the color value distribution condition of the single-channel gray image, and establishing a gray image color value distribution contour line;
setting the mesh points as mixed screening, wherein the mixed screening comprises frequency modulation screening and amplitude modulation screening;
selecting frequency modulation mesh points or amplitude modulation mesh points according to different color densities of each image;
printing pressure is debugged, high-hardness rubber cloth and a gasket are replaced, the liquid feeding amount of fountain solution is adjusted, the flow speed of cooling water of the printing machine is accelerated, and printing is produced.
2. The high-screen printing method according to claim 1, wherein the method for establishing the color value distribution contour of the gray image is specifically as follows:
establishing a contour line for the first time; establishing a primary contour line according to three levels of 0-10% of a bright tone area, 10-90% of a middle area and 90-100% of a dark tone area, and simply separating the bright tone area, the middle area and the dark tone area of the single-channel gray-scale image;
establishing a secondary contour line: and establishing secondary contour lines for the bright tone area and the dark tone area according to the tone change condition and the 1% gray level change level, and carrying out secondary division on the gray level change of the bright tone area and the dark tone area.
3. The high-screen printing method according to claim 1, wherein frequency-modulated screen dots are used to express 10-90% of the middle area, amplitude-modulated screen dots are used to express 0-10% of the bright area and 90-100% of the dark area, and the conversion point of amplitude modulation and frequency modulation is changed with the number of screen dots.
4. The high-screen printing method according to claim 3, wherein 2 to 3 small screen dots are combined into one larger screen dot in a 0 to 10% highlight portion.
5. The high-screen printing method according to claim 1, wherein the distribution of the screen dots is optimized on the principle of no overlap and no formation of large spaces.
6. The high-screen printing method according to claim 1, wherein the anilox roller of the printing press is provided as a trapezoidal-section diagonal cell; the ink carrying capacity of the anilox roller is 8-9cm3/m2。
7. The high-screen printing method according to claim 1, wherein the printing pressure is adjusted to 75-90% of the normal printing pressure at the time of printing.
8. The high-screen printing method according to claim 1, wherein the blanket hardness is 80 ° to 85 ° shore a, the surface smoothness is 0.9 to 1.0um, the elongation is less than 1.8%, and the reduction in thickness at elongation is less than 1.8% when printing.
9. The high-screen printing method of claim 1, wherein the highest density Dmax of the four-color printed matter is 2.0-2.1, and the density value of the four colors of the ink is C1.40-1.45M1.45-1.50 Y0.95K1.50-1.90.
10. The high-screen printing method according to claim 1, wherein the ink is a high-quality, high-viscosity four-color ink; the printing ink comprises, by weight, 42-45 parts of main body resin, 36-38 parts of reactive diluent, 24-26 parts of pigment, 8-12 parts of photoinitiator and 2-4 parts of auxiliary agent.
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| CN1913574A (en) * | 2006-08-31 | 2007-02-14 | 北京北大方正电子有限公司 | Frequency modulation amplitude modulation mixed network continuous modulation control method |
| CN109605969A (en) * | 2018-12-29 | 2019-04-12 | 星光印刷（苏州）有限公司 | A kind of fine Dot Color control method |
| CN110722888A (en) * | 2019-11-19 | 2020-01-24 | 深圳劲嘉集团股份有限公司 | Flexographic printing LED-UV ink and method for screen dot joint color printing of flexographic offset printing |
| CN110722889A (en) * | 2019-11-19 | 2020-01-24 | 东莞市美盈森环保科技有限公司 | Color control method for ultrahigh fine printing of image |
| CN110881091A (en) * | 2019-11-15 | 2020-03-13 | 东莞市美盈森环保科技有限公司 | Frequency-conversion amplitude-modulation screening method and image ultrahigh fine offset printing process |
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2020
- 2020-10-26 CN CN202011155967.9A patent/CN114475029A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1913574A (en) * | 2006-08-31 | 2007-02-14 | 北京北大方正电子有限公司 | Frequency modulation amplitude modulation mixed network continuous modulation control method |
| WO2008028409A1 (en) * | 2006-08-31 | 2008-03-13 | Peking University Founder Group Co., Ltd | Frequency modulation amplitude modulation mixed net point hierarchy continuous adjustment control method |
| CN109605969A (en) * | 2018-12-29 | 2019-04-12 | 星光印刷（苏州）有限公司 | A kind of fine Dot Color control method |
| CN110881091A (en) * | 2019-11-15 | 2020-03-13 | 东莞市美盈森环保科技有限公司 | Frequency-conversion amplitude-modulation screening method and image ultrahigh fine offset printing process |
| CN110722888A (en) * | 2019-11-19 | 2020-01-24 | 深圳劲嘉集团股份有限公司 | Flexographic printing LED-UV ink and method for screen dot joint color printing of flexographic offset printing |
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