CN115771330A - Correction method for electronic engraving intaglio plate - Google Patents
Correction method for electronic engraving intaglio plate Download PDFInfo
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- CN115771330A CN115771330A CN202211696304.7A CN202211696304A CN115771330A CN 115771330 A CN115771330 A CN 115771330A CN 202211696304 A CN202211696304 A CN 202211696304A CN 115771330 A CN115771330 A CN 115771330A
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Abstract
The invention discloses a correction method for electronic engraving intaglio plate making, which comprises the steps of inputting different current values according to set intervals on the premise of no correction to obtain a printed four-color ladder rule, measuring density values and solid density values on the four-color ladder rule to obtain the relation between the density values of the four-color ladder rule and corresponding engraving plate current values, respectively converting the density values into tone values a, and then converting the density values D into density values t And converting the relation between the current value and the target tone value into the relation between the tone value a and the engraving current value, setting a tone value increasing curve, converting the tone value increasing curve into a printing copy curve, obtaining the target tone value through the printing copy curve according to the relation between the tone value a and the engraving current value, thereby obtaining the engraving current value A, and finally performing linear correction. The correction method solves the quality problems of expanded dots, lower printing density and the like of the printed matter in the electronic engraving plate-making method in the prior art.
Description
Technical Field
The invention belongs to the technical field of gravure printing and electronic engraving gravure plate making, and relates to a correction method for electronic engraving gravure plate making.
Background
With the improvement of living standard, the requirements of people on the quality of printed matters become higher, and the high-quality printed matters not only can enable users to obtain better use feeling, but also can accurately transmit information to be expressed. Because the gravure printing can truly reproduce the original effect, has rich and clear layers and bright color, and can adopt water-based ink and alcohol-soluble ink, the gravure printing meets the requirement of green environment-friendly printing, can be widely applied to various media such as films, composite materials, paper and the like, becomes the second largest printing branch except offset lithography, and is the main printing mode of packaging printing.
Common in the gravure industry is: the importance of gravure platemaking is described by three-degree dependence on printing and seven-degree dependence on platemaking. Because of the different plate making processes, the gravure plate making method includes two types, namely corrosion plate making and engraving plate making. The corrosion plate making mode comprises a Blancei plate making mode and a photocopy plate making mode; the engraving plate-making mode comprises a manual engraving plate-making mode and an electronic engraving plate-making mode.
However, in the gravure printing process, problems of dot gain, low printing density and the like can occur due to changes of paper and ink performance, so that deviation of printing colors occurs to influence the quality of printed matters. At present, most documents only discuss and analyze factors influencing gravure printing and gravure plate making, and the document research on quality parameters of electronic engraving gravure plate making (Chen Shurong, academic thesis, beijing printing academy, 2013) analyzes the influence of the quality parameters of electronic engraving gravure plate making, such as engraving line number, screen line angle, engraving needle angle, screen dot value and the like, on the quality of printed matters. The common problems and the solutions of the printed matters caused by the gravure electroengraving plate making are analyzed in the document of common problems and solutions of the plastic gravure electroengraving plate making (Malan, printing today 2003 (01): 67-69). But no prior art researches on an electronic engraving intaglio plate making correction method.
Therefore, the invention aims at the electronic engraving intaglio plate making, corrects the electronic engraving intaglio plate in the intaglio printing process and ensures the quality of printed matters.
Disclosure of Invention
The invention aims to provide a correction method for electronic engraving intaglio plate making, which solves the quality problems of expanded screen dots, lower printing density and the like of a printed matter in the electronic engraving plate making method in the prior art.
The technical scheme adopted by the invention is that the correction method for the electronic engraving intaglio plate is implemented according to the following steps:
step 1, inputting different current values according to set intervals on the premise of no correction in the electronic engraving intaglio plate making process to obtain four-color stepscales of cyan C, magenta M, yellow Y and black K for printing;
step 2, measuring the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler obtained in the step 1 t And solid density values D of four colors of cyan C, magenta M, yellow Y and black K s According to the engraving current value corresponding to each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler in the step 1, the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler can be obtained t The relationship of the engraving current value corresponding to each color patch;
step 3, using a Murrier-Davis formula to obtain the density value D of each color block of the cyan C, magenta M, yellow Y and black K four-color ladder rule obtained in the step 2 t Respectively converting the values into tone values a, and then obtaining the density value D in the step 2 t Converting the relation between the current value and the level value a into the relation between the engraving current value and the level value a;
step 4, setting a tone value increasing curve, changing the abscissa of the tone value increasing curve into a tone value a, and changing the ordinate into the sum of the ordinate of the tone value increasing curve and the tone value a to be used as a printing copy curve;
and 6, carrying out linearization correction.
The present invention is also characterized in that,
in step 1, the current value is a value after normalization processing, i.e., 0 to 255.
In step 3, the merley-davis formula is as follows:
in the formula (1), a represents a tone value; d t Representing the dot reflection density of each color block on the four-color ladder ruler or the relative density of each color block on the four-color ladder ruler, if the dot reflection density is the relative density, D t Represents the absolute density of each patch minus the density of the paper; d s The relative density of the four solid densities of cyan C, magenta M, yellow Y and black K or the relative densities of the four colors of cyan C, magenta M, yellow Y and black K is D s The absolute density of each patch minus the density of the paper is indicated.
The specific process of step 5 is as follows:
step 5.1, inputting a tone value a according to the printing copy curve obtained in the step 4 to obtain a target tone value;
and 5.2, substituting the target tone value as the tone value a into the relation between the tone value a and the engraving current value according to the relation between the tone value a and the engraving current value obtained in the step 3, thereby obtaining the engraving current value A.
The specific process of step 6 is as follows:
step 6.1, setting standard cyan C, magenta M, yellow Y and black K four-color ladder rules;
step 6.2, obtaining a corresponding target tone value A by using the tone value of each color block of the four colors of the standard cyan C, the magenta M, the yellow Y and the black K in the step 6.1 according to the printing copy curve in the step 4, and substituting the target tone value A as the tone value a into the relation between the tone value a and the engraving current value according to the relation between the tone value a and the engraving current value obtained in the step 3, thereby obtaining an engraving current value B;
6.3, repeating the process of the step 1 by using the engraving current value B obtained in the step 6.2 to engrave the four-color ladder ruler again, proofing again, measuring according to the step 2, and converting into a tone value B according to the step 3;
step 6.4, obtaining the tone value B of each color block of the standard cyan C, magenta M, yellow Y and black K four colors in the step 6.1 according to the printing copy curve of the step 4;
step 6.5, comparing the tone value B obtained in the step 6.3 with the target tone value B obtained in the step 6.4 of each color block;
and 6.6, if the difference between the step B and the target step B in the step 6.5 is more than 1%, repeating the steps 6.2-6.5 until the difference is less than 1%, and finishing the correction.
In step 6.1, the colors of the standard cyan C, magenta M, yellow Y and black K four-color ladder rules are arranged one by one from light to dark, and each color block is increased from 0% of the tone value to 100% at set intervals.
The correction method for the electronic engraving intaglio plate has the advantages that the correction method for the electronic engraving intaglio plate can ensure the quality of printed matters through effective correction in the printing process, and meanwhile, unnecessary waste can be reduced, and time is saved.
Drawings
FIG. 1 is a graph illustrating the increase in the level of the method of the present invention;
FIG. 2 is a graph of a print copy curve in the method of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention provides a correction method for electronic engraving intaglio plate making, which is implemented by the following steps:
step 1, in the process of electronic engraving intaglio plate making, different-sized holes can be engraved on an engraving head at different current values, different ink amounts transferred in the printing process can be different, so that different gradations are generated, different normalized current values of 0-255 are input according to a set interval on the premise of no correction, a cyan C, magenta M, yellow Y and black K four-color step ruler printing plate with gradually changed color composition but irregular color composition can be engraved, and sampling is performed to obtain a printed cyan C, magenta M, yellow Y and black K four-color step ruler;
step 2, respectively measuring the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler obtained in the step 1 by using a spectrophotometer t And solid density values D of four colors of cyan C, magenta M, yellow Y and black K s (ii) a According to the engraving current value corresponding to each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler in the step 1, the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler can be obtained t The relationship of the engraving current values corresponding to each color patch;
step 3, using Murry-Davis formula to obtain density value D of each color block of the cyan C, magenta M, yellow Y and black K four-color ladder ruler obtained in the step 2 t Respectively converting into a tone value a, thereby obtaining the density value D in the step 2 t Converting the relation between the current value and the level value a into the relation between the engraving current value and the level value a;
the mery-Davis (Murry-Davis) formula is as follows:
in the formula (1), a represents a tone value; d t Representing the dot reflection density of each color block on the four-color ladder ruler or the relative density of each color block on the four-color ladder ruler, if the dot reflection density is the relative density, D is t Represents the absolute density of each patch minus the density of the paper; d s The relative density of the four solid densities of cyan C, magenta M, yellow Y and black K or the relative densities of the four colors of cyan C, magenta M, yellow Y and black K is D s Representing absolute densities of individual colour blocksDegree minus the density of the paper;
step 4, setting a tone value increasing curve, changing the abscissa of the tone value increasing curve into a tone value a, changing the ordinate into the sum of the ordinate of the tone value increasing curve and the tone value a, and then using the sum as a printing copy curve, wherein the ordinate of the printing copy curve represents a target tone value;
as shown in fig. 1, the tone value increasing curve is one of a relevant curve or a custom curve in the ISO 12647 standard;
step 5.1, inputting a tone value a according to the printing copy curve obtained in the step 4 to obtain a target tone value;
step 5.2, according to the relation between the tone value a and the engraving current value obtained in the step 3, substituting the target tone value as the tone value a into the relation between the tone value a and the engraving current value so as to obtain an engraving current value A;
step 6, linear correction;
step 6.1, setting standard cyan C, magenta M, yellow Y and black K four-color ladder rules;
color blocks of the standard cyan C, magenta M, yellow Y and black K four-color ladder ruler are arranged one by one from light to dark, each color block is increased from 0% of tone value to 100% at certain intervals (generally 10%, the intervals can be reduced in highlight and dark tone parts), for example, the tone value of each color block is 0%, 2%, 3%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 97%, 98% and 100%;
step 6.2, obtaining a corresponding target tone value A by using the tone value of each color block of the four colors of the standard cyan C, the magenta M, the yellow Y and the black K in the step 6.1 according to the printing copy curve in the step 4, and substituting the target tone value A as the tone value a into the relation between the tone value a and the engraving current value according to the relation between the tone value a and the engraving current value obtained in the step 3, thereby obtaining an engraving current value B;
6.3, repeating the process of the step 1 by using the engraving current value B obtained in the step 6.2 to engrave the four-color ladder ruler again, proofing again, measuring according to the step 2, and converting into a tone value B according to the step 3;
step 6.4, obtaining the tone value B of each color block of the standard cyan C, magenta M, yellow Y and black K four colors in the step 6.1 according to the printing copy curve of the step 4;
step 6.5, comparing the tone value B obtained in the step 6.3 with the target tone value B obtained in the step 6.4 of each color block;
and 6.6, if the difference between the step B and the target step B in the step 6.5 is more than 1%, repeating the step 6.2 to the step 6.5 until the difference is less than 1%, and finishing the correction.
Examples
Step 1, in the process of electronic engraving intaglio plate making, different-sized holes can be engraved on an engraving head at different current values, different ink amounts transferred in the printing process can be different, so that different gradations are generated, different normalized current values of 0-255 are input according to a set interval on the premise of no correction, a cyan C, magenta M, yellow Y and black K four-color step scale printing plate with gradually changed color composition and irregular color composition can be engraved, and the printing is carried out to obtain a printed four-color step scale;
step 2, respectively measuring the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler obtained in the step 1 by using a spectrophotometer t And solid density values D of four colors of cyan C, magenta M, yellow Y and black K s (ii) a According to the engraving current value corresponding to each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler in the step 1, the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler can be obtained t The relationship of the engraving current values corresponding to each color patch, as shown in table 1;
TABLE 1 relationship between density values of color blocks on four-color ladder ruler and engraving current values corresponding to the color blocks
Step 3, using Murry-Davis formula to obtain density value D of each color block of the cyan C, magenta M, yellow Y and black K four-color ladder ruler obtained in the step 2 t Respectively converting into a tone value a, thereby obtaining the density value D in the step 2 t The relationship with the current value was converted into a relationship between the tone value a and the engraving current value, as shown in Table 2;
TABLE 2 relationship of tone value a to engraving current value
Step 4, setting a tone value increasing curve (as shown in fig. 2, a curve A in the tone expanding curve of ISO 12647-2 is selected), changing the abscissa of the tone value increasing curve into a tone value a, changing the ordinate into the sum of the ordinate of the tone value increasing curve and the tone value a to be used as a printing copy curve, and expressing the ordinate of the printing copy curve as a target tone value;
step 5.1, inputting a tone value a according to the printing copy curve obtained in the step 4 to obtain a target tone value, as shown in table 3;
step 5.2, according to the relation between the tone value a and the engraving current value obtained in the step 3, substituting the target tone value as the tone value a into the relation between the tone value a and the engraving current value so as to obtain an engraving current value A;
TABLE 3 tone value a and target tone value
Step 6.1, setting standard cyan C, magenta M, yellow Y and black K four-color ladder rules;
color blocks are arranged one by one from light to dark in the colors of a standard cyan C, magenta M, yellow Y and black K four-color ladder ruler, each color block is increased from a tone value of 0% to 100% in a certain interval (generally 10%, the interval can be reduced in highlight and dark tone parts), and the tone value of each color block is set to be 0%, 2%, 3%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 97%, 98% and 100%;
step 6.2, obtaining a corresponding target tone value A by using the tone value of each color block of the four colors of the standard cyan C, the magenta M, the yellow Y and the black K in the step 6.1 according to the printing copy curve in the step 4, and substituting the target tone value A as the tone value a into the relation between the tone value a and the engraving current value according to the relation between the tone value a and the engraving current value obtained in the step 3, thereby obtaining an engraving current value B, wherein the table 4 shows the target tone value A;
TABLE 4 engraving Current value B
6.3, repeating the process of the step 1 by using the engraving current value B obtained in the step 6.2 to engrave the four-color ladder ruler again, proofing again, measuring according to the step 2, and converting into a tone value B according to the step 3;
step 6.4, obtaining the tone value of each color block of the four colors of the standard cyan C, the magenta M, the yellow Y and the black K in the step 6.1 according to the printing copy curve of the step 4 to obtain a target tone value B of each color block, as shown in the table 5;
TABLE 5 tone value B and target tone value B
Step 6.5, comparing the tone value B obtained in the step 6.3 with the target tone value B obtained in the step 6.4 of each color block; and 6.6, if the difference between the step B and the target step B in the step 6.5 is more than 1%, repeating the steps 6.2-6.5 until the difference is less than 1%, and finishing the correction.
Claims (6)
1. The correction method for the electronic engraving intaglio plate is characterized by comprising the following steps of:
step 1, inputting different current values according to set intervals on the premise of no correction in the electronic engraving intaglio plate making process to obtain four-color stepscales of cyan C, magenta M, yellow Y and black K for printing;
step 2, measuring the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler obtained in the step 1 t And solid density values D of four colors of cyan C, magenta M, yellow Y and black K s According to the engraving current value corresponding to each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler in the step 1, the density value D of each color block on the cyan C, magenta M, yellow Y and black K four-color ladder ruler can be obtained t The relationship of the engraving current values corresponding to each color patch;
step 3, using a Murrier-Davis formula to obtain the density value D of each color block of the cyan C, magenta M, yellow Y and black K four-color ladder ruler obtained in the step 2 t Respectively converting into a tone value a, and then converting the density value D in the step 2 t Converting the relation with the current value into the relation between a tone value a and the engraving current value;
step 4, setting a tone value increasing curve, changing the abscissa of the tone value increasing curve into a tone value a, and changing the ordinate into the sum of the ordinate of the tone value increasing curve and the tone value a to be used as a printing copy curve;
step 5, obtaining a target tone value through printing a copy curve in the step 4 according to the relationship between the tone value a obtained in the step 3 and the engraving current value, so as to obtain an engraving current value A;
and 6, carrying out linearization correction.
2. The correction method for the electronic engraving plate-making according to claim 1, wherein in step 1, the current value is a normalized value of 0 to 255.
3. The correction method for electroengraving intaglio plate-making according to claim 1, wherein in step 3, the mery-davis formula is as follows:
in the formula (1), a represents a tone value; d t Representing the dot reflection density of each color block on the four-color ladder ruler or the relative density of each color block on the four-color ladder ruler, if the dot reflection density is the relative density, D t Represents the absolute density of each patch minus the density of the paper; d s The relative density of the four colors cyan C, magenta M, yellow Y and black K, D s The absolute density of each patch minus the density of the paper is indicated.
4. The correction method for electronic engraving intaglio plate making according to claim 1, wherein in step 3, the specific process of step 5 is as follows:
step 5.1, inputting the tone value a according to the printing copy curve obtained in the step 4 to obtain a target tone value;
and 5.2, substituting the target tone value as the tone value a into the relation between the tone value a and the engraving current value according to the relation between the tone value a and the engraving current value obtained in the step 3, thereby obtaining the engraving current value A.
5. The correction method for electronic engraving intaglio plate making according to claim 1, characterized in that in step 3, the specific process of step 6 is as follows:
step 6.1, setting standard cyan C, magenta M, yellow Y and black K four-color ladder rules;
step 6.2, obtaining a corresponding target tone value A by using the tone value of each color block of the four colors of the standard cyan C, the magenta M, the yellow Y and the black K in the step 6.1 according to the printing copy curve in the step 4, and substituting the target tone value A serving as the tone value a into the relation between the tone value a and the engraving current value according to the relation between the tone value a and the engraving current value obtained in the step 3, thereby obtaining an engraving current value B;
6.3, repeating the process of the step 1 by using the engraving current value B obtained in the step 6.2 to engrave the four-color ladder ruler again, proofing again, measuring according to the step 2, and converting into a tone value B according to the step 3;
step 6.4, obtaining the tone value B of each color block of the standard cyan C, magenta M, yellow Y and black K four colors in the step 6.1 according to the printing copy curve of the step 4;
step 6.5, comparing the tone value B obtained in the step 6.3 with the target tone value B obtained in the step 6.4 of each color block;
and 6.6, if the difference between the step B and the target step B in the step 6.5 is more than 1%, repeating the steps 6.2-6.5 until the difference is less than 1%, and finishing the correction.
6. The method for correcting the electronic engraving intaglio plate-making according to claim 5, wherein in step 6.1, the colors of the standard cyan C, magenta M, yellow Y and black K four-color scales are arranged one by one from light to dark, and each color block is increased from a tone value of 0% to 100% at set intervals.
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