Method and device for determining color difference of printed matter, equipment and medium

Abstract

The embodiment of the invention provides a method, device and equipment for determining the color difference of printed matters and a medium. The method comprises the following steps: acquiring a first electronic part of a standard sample page and a second electronic part of a printing sample page; partitioning the first electronic part and the second electronic part based on a predetermined size; determining a difference value between the LAB value of each partition of the first electronic part and the LAB value of the corresponding partition of the second electronic part; determining the color of each partition based on the difference value; and based on the color of each partition, determining a color difference graph representing the color difference between the standard sample page and the printing sample page. And color comparison does not depend on human eyes of a collar machine, so that the labor cost is reduced. Local color correction marks are not depended on, the width of printed sheets does not need to be increased, and consumption of printing paper is reduced. The display color difference can be quantified based on the different colors with the distinguishing effect, the printed matter can be accurately evaluated, and printing parameters can be adjusted in a targeted mode.

Description

Technical Field

[0001] The present invention belongs to the field of typesetting, publishing and printing technology, in particular to a method, device, equipment and medium for determining color differences of printed products. Background Art

[0002] During the printing process of color prints in a printing factory, a very important link is to ensure that the color of the finished print ("printed sample") is highly consistent with the color of the printed target ("standard sample"), and that the "printed samples" between different batches of different printing factories, different printing equipment and the same printing equipment in different places maintain the same color consistency standard.

[0003] The color of a printed product comes from the color of light reflected by the printed product as perceived by the human eye. The four-color printing mode is a color mode used in color printing. It uses the principle of mixing the three primary colors of the colorant, plus black ink, to mix and superimpose a total of four colors to form the so-called "full-color printing". The four standard colors are: cyan (C, Cyan), also known as "sky blue" or "deep blue"; magenta (M, Magenta), also known as "magenta"; yellow (Y, Yellow); black (K, blacK), the abbreviation here uses the last letter K instead of the initial B to avoid confusion with blue. In printing, these four colors can usually reproduce thousands of other colors. The CMYK mode is a subtractive color mode, and the corresponding red, green, and blue (RGB) mode is an additive color mode. The colors on printed products are usually formed by the superposition of the four colors of yellow, red, blue, and black (CMYK). Summary of the invention

[0004] The embodiments of the present invention provide a method, an apparatus, a device and a medium for determining the color difference of printed products.

[0005] The technical solution of the embodiment of the present invention is as follows:

[0006] A method for determining color differences in printed matter, comprising:

[0007] Obtaining a first electronic copy of the standard proof and a second electronic copy of the printed proof;

[0008] partitioning the first electronic component and the second electronic component based on a predetermined size;

[0009] Determine the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component;

[0010] Based on the difference, determining the color of each partition;

[0011] Based on the color of each partition, a color difference diagram representing the color difference between the standard proof and the printed proof is determined.

[0012] In one embodiment, the color mode of the first electronic component and the second electronic component is an RGB color mode or a CMYK color mode;

[0013] Determining the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component includes at least one of the following:

[0014] Calculate a first average RGB value or a first average CMYK value of all pixels of each partition of the first electronic component; convert the first average RGB value or the first average CMYK value into a first average LAB value of each partition; calculate a second average RGB value or a second average CMYK value of all pixels of a corresponding partition of the second electronic component; convert the second average RGB value or the second average CMYK value into a second average LAB value of the corresponding partition; determine a difference between the first average LAB value and the second average LAB value;

[0015] Convert the RGB value or CMYK value of each pixel point of each partition of the first electronic component into a LAB value; determine the third average LAB value of each partition of the first electronic component based on the LAB value of each pixel point of each partition of the first electronic component; convert the RGB value or CMYK value of each pixel point of the corresponding partition of the second electronic component into a LAB value; determine the fourth average LAB value of the corresponding partition of the second electronic component based on the LAB value of each pixel point of the corresponding partition of the second electronic component; determine the difference between the third average LAB value and the fourth average LAB value;

[0016] Convert the RGB value or CMYK value of each pixel point of each partition of the first electronic component into a LAB value; convert the RGB value or CMYK value of the corresponding pixel point of the corresponding partition of the second electronic component into a LAB value; determine the average value of all differences between the LAB values ​​of all pixel points of each partition of the first electronic component and the LAB values ​​of the corresponding pixel points of the corresponding partition of the second electronic component.

[0017] In one embodiment, determining the color of each partition based on the difference includes:

[0018] Determine the numerical interval to which the difference value of each partition belongs within a predetermined set of numerical intervals;

[0019] The color of each partition is determined based on the correspondence between the numerical range and the predetermined color.

[0020] In one embodiment, the set of numerical intervals includes a first numerical interval, a second numerical interval, and a third numerical interval, wherein the maximum value of the first numerical interval is less than or equal to the minimum value of the second numerical interval, and the maximum value of the second numerical interval is less than or equal to the minimum value of the third numerical interval;

[0021] The color of the partition includes at least one of the following:

[0022] Green; yellow; red; black.

[0023] In one embodiment, it includes:

[0024] Counting the color distribution in the color difference map;

[0025] Based on the color distribution, the acceptability of the printed proof is evaluated.

[0026] In one embodiment, the evaluating the acceptability of the printed proof based on the color distribution includes at least one of the following:

[0027] When the number of partitions of the color in the color difference diagram corresponding to the third value interval is greater than a first predetermined threshold, determining that the printed sample is unqualified;

[0028] When the number of partitions of the color in the color difference diagram corresponding to the first value interval is less than a second predetermined threshold, determining that the printed sample is unqualified;

[0029] When the number of partitions in the color difference diagram corresponding to the second value interval is greater than a third predetermined threshold, determining that the printed sample is unqualified, wherein the third predetermined threshold is greater than the first predetermined threshold;

[0030] When the number of continuous partitions of the color in the color difference diagram corresponding to the second value interval is greater than a fourth predetermined threshold, determining that the printed proof is unqualified, wherein the fourth predetermined threshold is less than the third predetermined threshold;

[0031] When the number of continuous partitions of the colors in the color difference diagram corresponding to the third value interval is greater than a fifth predetermined threshold, the printed proof is determined to be unqualified, wherein the fifth predetermined threshold is less than the first predetermined threshold.

[0032] In one embodiment, it includes:

[0033] Based on the entirety of the color difference diagram, adjusting the total amount of ink supplied by the printing device of the printing sample with respect to each color of yellow, red, blue and black;

[0034] Based on the part of the color difference diagram, the ink supply amount of each color of yellow, red, blue and black in the ink lower channel corresponding to the part of the printing device of the printing sample is adjusted.

[0035] A device for determining color differences of printed matter, comprising:

[0036] An acquisition module, used for acquiring a first electronic copy of a standard sample and a second electronic copy of a printed sample;

[0037] A partitioning module, configured to partition the first electronic component and the second electronic component based on a predetermined size;

[0038] A first determination module, configured to determine a difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component;

[0039] A second determination module, configured to determine the color of each partition based on the difference;

[0040] The third determination module is used to determine a color difference diagram representing the color difference between the standard sample and the printed sample based on the color of each partition.

[0041] An electronic device, comprising:

[0042] processor;

[0043] A memory, configured to store executable instructions of the processor;

[0044] The processor is used to read the executable instructions from the memory and execute the executable instructions to implement any of the above methods for determining color differences of printed products.

[0045] A computer-readable storage medium stores computer instructions, which, when executed by a processor, implement any of the above methods for determining color differences of printed products.

[0046] A computer program product comprises a computer program, wherein when the computer program is executed by a processor, the method for determining color differences of printed products as described above is implemented.

[0047] It can be seen from the above technical scheme that in the embodiment of the present invention, the first electronic part of the standard proof and the second electronic part of the printed proof are obtained; based on the predetermined size, the first electronic part and the second electronic part are partitioned; the difference between the LAB value of each partition of the first electronic part and the LAB value of the corresponding partition of the second electronic part is determined; based on the difference, the color of each partition is determined; based on the color of each partition, a color difference diagram representing the color difference between the printed proof and the standard proof is determined. It does not rely on the human eye of the leader to compare colors, which reduces labor costs. It does not rely on local color calibration marks, does not need to increase the width of the printed sheet, and reduces the consumption of printing paper. The color difference can be quantitatively displayed based on different colors with distinguishing effects, which helps to accurately evaluate printed products and can adjust printing parameters in a targeted manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The present invention is a flowchart of a method for determining color differences of printed products according to an embodiment of the present invention.

[0049] Figure 2 is a first exemplary color difference diagram representing the color difference between a standard proof and a printed proof according to an embodiment of the present invention.

[0050] Figure 3 is a second exemplary color difference diagram representing the color difference between a standard proof and a printed proof according to an embodiment of the present invention.

[0051] Figure 4 is a first exemplary color difference diagram representing the color difference between a standard proof and a printed proof according to an embodiment of the present invention.

[0052] Figure 5 4 is a structural diagram of a device for determining color differences of printed products according to an embodiment of the present invention.

[0053] Figure 6 is a structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings.

[0055] For the sake of brevity and intuitiveness in description, the scheme of the present invention is explained below by describing several representative implementations. A large number of details in the implementations are only used to help understand the scheme of the present invention. However, it is obvious that the technical scheme of the present invention may not be limited to these details when implemented. In order to avoid unnecessarily obscuring the scheme of the present invention, some implementations are not described in detail, but only a framework is given. Hereinafter, "including" means "including but not limited to", and "according to..." means "at least according to..., but not limited to only according to...". Due to the language habits of Chinese, when the number of a component is not specifically specified below, it means that the component can be one or more, or can be understood as at least one.

[0056] After research, the applicant found that the traditional color difference comparison method mainly relies on the naked eye of the printer leader to measure and compare, and judges whether the color difference between the "printed sample" and the "standard sample" meets the delivery requirements based on experience. This processing method relies too much on the experience of the printer leader and the sensitivity of the naked eye to color, and lacks quantitative standards, resulting in large color differences between different printing plants, different printing equipment, and different printings.

[0057] To solve the color difference problem, the common technical means at present is to use a colorimeter (or spectrodensitometer) to measure the LAB value of the same coordinate position of the "standard sample" and the "printed sample", and to quantify the degree of color difference based on the difference in the calculated LAB value (generally called Delta-E value). However, since the sampling area is very small (millimeter level), when the sampling coordinate position in common printing tasks is slightly deviated, it will cause the test points to not correspond and the test to be inaccurate. Therefore, in general tests, the color difference of the position of a special "color bar" is required to infer the global color difference of the printed product based on the local color difference of the color bar. However, this speculation is incomplete and inaccurate. In addition, adding a color bar printing position to the printed product also requires increasing the width of the printed sheet and increasing the consumption of printing paper. In addition, distributing "standard samples" to printing plants in various places is also time-consuming and labor-intensive, and affects the delivery cycle of printed products.

[0058] The above disclosure details the technical defects existing in the prior art, the causes of the technical defects, and the thinking and analysis process of overcoming the technical defects. In fact, the cognition of the above technical defects is not common knowledge in the field, but a novel discovery made by the applicant in research. In addition, the cause tracing of the technical defects and the thinking and analysis process of overcoming the technical defects are also the gradual analysis results of the applicant in the actual research process, and are not common knowledge in the field.

[0059] Figure 1 The present invention is a flowchart of a method for determining color differences of printed products according to an embodiment of the present invention. Figure 1 The method shown can be executed by the print contractor or by the printer.

[0060] like Figure 1 As shown, the method includes:

[0061] Step 101: Obtain a first electronic copy of a standard sample and a second electronic copy of a printed sample.

[0062] Here, a scanning device (such as an electronic scanner or a camera) can be used to scan a standard sample of a paper document and a printed sample of a paper document to generate a first electronic part and a second electronic part. The first electronic part and the first electronic part can be implemented as image files, such as JPEG, GIF, TIFF, PNG, RAW or PDF formats.

[0063] In one embodiment, when the printing contract issuing party specifically performs Figure 1In the method shown, the print contractor can scan the standard sample of the paper document to obtain the first electronic copy. At this time, the print contractor can obtain the second electronic copy of the printed sample from the printing party via network communication (wherein: when the printing party scans the printed sample of the paper document to generate the second electronic copy, the scanning device used by the printing party is preferably the same model as the scanning device of the print contractor, and the scanning environment is the same (for example, the same standard light source; the same light source cooling; the same working temperature, etc.)). Alternatively, the print contractor can obtain the printed sample of the paper document from the printing party (for example, via logistics methods such as postal express delivery), and then the print contractor scans the printed sample of the paper document to obtain the second electronic copy. Wherein: when the print contractor scans the printed sample of the paper document to generate the second electronic copy, the scanning device used by the print contractor is the same model as the scanning device used when scanning the standard sample of the paper document, and the scanning environment is the same (for example, the same standard light source; the same light source cooling; the same working temperature, etc.).

[0064] In one embodiment, when the printing side specifically performs Figure 1 In the method shown, the printing party can scan the printed sample of the paper document to obtain the second electronic copy. At this time, the printing party can obtain the first electronic copy of the standard sample from the printing contractor via network communication (wherein: when the printing contractor scans the standard sample of the paper document to generate the first electronic copy, the scanning device used by the printing contractor is preferably the same model as the scanning device of the printing party, and the scanning environment is the same (for example, the same standard light source; the same light source cooling; the same working temperature, etc.)). Alternatively, the printing party can obtain the standard sample of the paper document from the printing contractor (for example, via logistics methods such as postal express delivery), and then the printing party scans the standard sample of the paper document to obtain the first electronic copy. Wherein: when the printing party scans the printed sample of the paper document to generate the first electronic copy, the scanning device used by the printing party is the same model as the scanning device used when scanning the printed sample of the paper document, and the scanning environment is the same (for example, the same standard light source; the same light source cooling; the same working temperature, etc.).

[0065] Step 102: partitioning the first electronic component and the second electronic component based on a predetermined size.

[0066] The printed proof and the standard proof have the same physical size, and the scanning parameters (such as scanning device model and resolution setting, etc.) during the scanning process of the printed proof and the standard proof are the same, so the second electronic component and the first electronic component have the same pixel size.

[0067] Here, the first electronic component and the second electronic component are partitioned based on a predetermined size. Since the first electronic component and the second electronic component have the same pixel size, the partitioning results of the first electronic component and the second electronic component are the same. Preferably, the size can be set, which can be at the pixel level. For example, the size can be set to a pixel block of 20*20, 40*40 or 80*80. Taking the size as the partitioning unit, all the pixel points of the first electronic component and the second electronic component can be partitioned to obtain the corresponding partitioning results.

[0068] For example: Assuming that both the first electronic component and the second electronic component have 10 million pixels, and the partition size is 20*20, the first electronic component and the second electronic component can be divided into 1000 / 0.04=25,000 partitions respectively. For each partition in the first electronic component, there is a corresponding partition at the same position in the second electronic component. Since there may be remainders, some of the remaining pixels may not be partitioned, and these remaining pixels can be combined into one partition.

[0069] Step 103: Determine the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component.

[0070] Lab values ​​are numerical values ​​used to represent colors in the CIELab color space. CIELab is a color model published by CIE (International Commission on Illumination), which theoretically includes all colors visible to the human eye. The Lab color model usually consists of three elements: brightness (L) and a and b related to color, where: L represents the brightness of the color (black and white); a represents the range from red to green, with a value range of [-128,127], where +127 represents red and -128 represents green; b represents the range from yellow to blue, with a value range of [-128,127], where +127 represents yellow and -128 represents blue.

[0071] In practical applications, Lab values ​​can be automatically obtained through professional color measurement equipment (such as colorimeter) or image processing software. These devices or software have integrated corresponding algorithms and models, which can accurately convert colors from other color modes (such as RGB, CMYK, etc.) to Lab values.

[0072] Here, the color mode of the first electronic component and the second electronic component can be an RGB color mode or a CMYK color mode. In one embodiment, determining the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component includes at least one of the following:

[0073] (1) Calculate the first average RGB value or the first average CMYK value of all pixels of each partition of the first electronic component; convert the first average RGB value or the first average CMYK value into the first average LAB value of each partition; calculate the second average RGB value or the second average CMYK value of all pixels of the corresponding partition of the second electronic component; convert the second average RGB value or the second average CMYK value into the second average LAB value of the corresponding partition; determine the difference between the first average LAB value and the second average LAB value (that is, the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component).

[0074] For example: Assuming that the first electronic component and the second electronic component are both RGB files, both have 10 million pixels, and the partition size is 20*20, then the first electronic component and the second electronic component can be divided into 25,000 identical partitions accordingly.

[0075] First, the average RGB values ​​of all pixels in each partition of the first electronic component are calculated respectively, so as to obtain 25,000 first average RGB values ​​(each partition has its own first average RGB value), and based on the RGB to LAB algorithm, these 25,000 first average RGB values ​​are converted into 25,000 first average LAB values ​​(each partition has its own first average LAB value). The average RGB values ​​of all pixels in each partition of the second electronic component are calculated respectively, so as to obtain 25,000 second average RGB values ​​(each partition has its own second average RGB value), and based on the RGB to LAB algorithm, these 25,000 second average RGB values ​​are converted into 25,000 second average LAB values ​​(each partition has its own second average LAB value).

[0076] Then, the difference between the first average LAB value of each partition in the first electronic component and the second average LAB value of the corresponding partition in the second electronic component (the relative position of the corresponding partition in the second electronic component in the second electronic component is the same as the relative position of the partition in the first electronic component in the first electronic component) is calculated. Accordingly, 25,000 differences corresponding to the 25,000 partitions can be calculated.

[0077] In this processing method, the average value of all pixels in each partition is first taken, and then the pixel average value is converted into a LAB value and the difference is calculated, which can simplify the calculation process of the LAB value and speed up the calculation.

[0078] (2) Convert the RGB value or CMYK value of each pixel point of each partition of the first electronic component into a LAB value; determine a third average LAB value of each partition of the first electronic component based on the LAB value of each pixel point of each partition of the first electronic component; convert the RGB value or CMYK value of each pixel point of the corresponding partition of the second electronic component into a LAB value; determine a fourth average LAB value of the corresponding partition of the second electronic component based on the LAB value of each pixel point of the corresponding partition of the second electronic component; and determine the difference between the third average LAB value and the fourth average LAB value (i.e., the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component).

[0079] For example: Assuming that the first electronic component and the second electronic component are both RGB files, both have 10 million pixels, and the partition size is 20*20, then the first electronic component and the second electronic component can be divided into 25,000 identical partitions accordingly.

[0080] For each of the 25,000 partitions: (a) calculate the RGB value of each pixel point in the first electronic component, so that 20*20 RGB values ​​are calculated for the partition; (b) convert the 20*20 RGB values ​​of the partition in the first electronic component into LAB values ​​one by one, and 20*20 LAB values ​​can be obtained; (c) determine the average value of the 20*20 LAB values ​​of the partition in the first electronic component (i.e., the third average LAB value); (d ... second electronic component, so that 20*20 RGB values ​​of the partition are calculated; (d) convert the RGB value of each pixel point in the first electronic component, so that 20*20 RGB values ​​of the partition are calculated; (e) convert the RGB value of each pixel point in the first electronic component, so that 20*20 LAB values ​​of the partition are calculated; (e) convert the RGB value of each pixel point in the first electronic component, so that 20*20 LAB values ​​of the partition are calculated; (f) convert the RGB value of each pixel point in the second electronic component, so that 20*20 RGB values ​​of the partition are calculated; (g) convert the RGB value of each pixel point in the first electronic component, so that 20*20 LAB values ​​of the partition are calculated; (g) convert the RGB value of each pixel point in the second electronic component, so that 20*20 RGB values ​​of the partition are calculated; (g) convert the RGB value of each pixel point in the first electronic The RGB value of each pixel point of the corresponding partition of the partition is obtained, so 20*20 RGB values ​​are calculated for each corresponding partition; (e) the 20*20 RGB values ​​of the corresponding partition of the partition in the second electronic component are converted one by one into LAB values, and 20*20 LAB values ​​can be obtained; (f) the average value of the 20*20 LAB values ​​of the corresponding partition of the partition in the second electronic component (i.e., the fourth average LAB value) is determined; (g) the difference between the third average LAB value and the fourth average LAB value is calculated.

[0081] Therefore, 25,000 differences corresponding to the 25,000 partitions can be calculated.

[0082] In this processing method, each pixel point in each partition is converted into a LAB value and then the average and difference are calculated, thus achieving pixel-level LAB processing with higher processing accuracy.

[0083] (3) Convert the RGB value or CMYK value of each pixel point of each partition of the first electronic component into a LAB value; convert the RGB value or CMYK value of the corresponding pixel point of the corresponding partition of the second electronic component into a LAB value; determine the average value of all differences between the LAB values ​​of all pixel points of each partition of the first electronic component and the LAB values ​​of the corresponding pixel points of the corresponding partition of the second electronic component (that is, the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component).

[0084] For example: Assuming that the first electronic component and the second electronic component are both RGB files, both have 10 million pixels, and the partition size is 20*20, then the first electronic component and the second electronic component can be divided into 25,000 identical partitions accordingly.

[0085] For each of the 25,000 partitions: (a) calculate the RGB value of each pixel point in the first electronic component, so that 20*20 RGB values ​​are calculated for the partition; (b) convert the 20*20 RGB values ​​of the partition in the first electronic component into 20*20 LAB values; (c) calculate the RGB value of each pixel point in the partition corresponding to the partition in the second electronic component, so that 20*20 RGB values ​​are calculated for the partition corresponding to the partition; (d) convert the 20*20 RGB values ​​of the partition corresponding to the partition in the second electronic component into 20*20 LAB values; (e) determine the difference between the LAB value of each pixel point in the partition in the first electronic component and the corresponding pixel point in the corresponding partition in the second electronic component, thereby obtaining 20*20 differences; (f) calculate the average value of these 20*20 differences.

[0086] Thus, 25,000 differences corresponding to the 25,000 partitions can be calculated.

[0087] In this processing method, each pixel point in each partition is converted into a LAB value and then the difference is calculated, and finally the difference is averaged, thus realizing pixel-level LAB processing with higher processing accuracy.

[0088] The difference between the LAB value of the partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component determined in step 103 can be called the partition color difference value (denoted as △E). Generally, when △E is between 0-1, the color difference between the partitions (between the partition of the first electronic component and the corresponding partition of the second electronic component) cannot be distinguished by the naked eye; when △E is between 1-2, the color difference of the partitions can be slightly perceived by the naked eye; when △E is between 2-3, the color difference of the partitions can be slightly distinguished; when △E is between 3.5-5, the color difference is very obvious; when △E is above 5, the color difference is very large, and it even looks like two colors.

[0089] Step 104: Determine the color of each partition based on the difference.

[0090] In one embodiment, determining the color of each partition based on the difference includes: determining the numerical interval to which the difference of each partition belongs within a predetermined set of numerical intervals; and determining the color of each partition based on the correspondence between the numerical interval and the predetermined color.

[0091] Take the example that the value interval set includes three value intervals. In one embodiment, the value interval set includes a first value interval, a second value interval, and a third value interval, wherein the maximum value of the first value interval is less than or equal to the minimum value of the second value interval, and the maximum value of the second value interval is less than or equal to the minimum value of the third value interval; the color of the partition includes at least one of the following: green; yellow; red; black.

[0092] For example: when the partition difference is in the interval [0,3], the color of the partition is green; when the partition difference is in the interval (3,5], the color of the partition is yellow; when the partition difference is in the interval (5,8], the color of the partition is red; when the partition difference is greater than 8, the color of the partition is black.

[0093] The above exemplary descriptions are typical examples of numerical intervals and corresponding colors. Those skilled in the art will appreciate that such descriptions are merely exemplary and are not intended to limit the scope of protection of the embodiments of the present invention. For example, the number of numerical intervals in the numerical interval set may be changed, the corresponding color of each numerical interval may also be changed, and so on.

[0094] Step 106: Based on the color of each partition, determine a color difference diagram representing the color difference between the standard sample and the printed sample.

[0095] Here, based on the color of each partition, a color difference diagram representing the color difference between the standard sample and the printed sample is determined. By browsing the entire color difference diagram, the overall color difference difference between the standard sample and the printed sample can be intuitively found, and by browsing a part of the color difference diagram, the local color difference difference between the standard sample and the printed sample can be intuitively found.

[0096] In one embodiment, in the color difference map, the partition is displayed based on the color of the partition in a manner equivalent to the actual size of the partition in the first electronic component. In one embodiment, in the color difference map, the actual size of the partition in the first electronic component is proportionally enlarged or reduced and displayed based on the color of the partition. In the color difference map, each partition can be displayed using a geometric shape equivalent to the size in the partition, or each partition can be displayed using a predetermined geometric shape. For example, when the partition size is a square, each partition can be displayed in the color difference map using a square of the same size (filled with a corresponding color), or each partition can be displayed in the color difference map using a square of a proportionally reduced size (filled with a corresponding color), or each partition can be displayed in the color difference map using a circle (filled with a corresponding color).

[0097] Preferably, the color difference diagram is displayed on a display screen, so that all color differences between the standard proof and the printed proof can be intuitively displayed.

[0098] Figure 2 is a first exemplary color difference diagram representing the color difference between the standard proof and the printed proof according to an embodiment of the present invention. Figure 2 In the figure, the green area is large, the yellow area is small, and there is almost no red area. Therefore, it can be determined that the color difference between the printed sample and the standard sample is small, and the printing quality is better.

[0099] Figure 3 is a second exemplary color difference diagram representing the color difference between the standard proof and the printed proof according to an embodiment of the present invention. Figure 3 In the figure, the green area is large, the yellow area is small, and there is a red area. Therefore, it can be determined that the color difference between the printed sample and the standard sample is average, and the printing quality is average.

[0100] Figure 4 is a first exemplary color difference diagram representing the color difference between the standard proof and the printed proof according to an embodiment of the present invention. Figure 4 In the figure, the green area is small, the yellow area is large and there are continuous areas of large areas, and there are continuous red areas of large areas. Therefore, it can be determined that the color difference between the printed sample and the standard sample is large, and the printing quality is poor.

[0101] In addition to intuitively displaying all color differences between the standard proof and the printed proof, the embodiment of the present invention can also quantitatively evaluate the eligibility of the printed proof based on the statistical results of color distribution.

[0102] In one embodiment, Figure 1 The method includes: statistically analyzing the color distribution in the color difference diagram; and evaluating the acceptability of the printed sample based on the color distribution.

[0103] In one embodiment, based on the color distribution, evaluating the acceptability of the printed proof includes at least one of the following:

[0104] (1) when the number of partitions of the color in the color difference diagram corresponding to the third value interval is greater than a first predetermined threshold, determining that the printed sample is unqualified;

[0105] (2) when the number of partitions of the color in the color difference diagram corresponding to the first value interval is less than a second predetermined threshold, determining that the printed sample is unqualified;

[0106] (3) when the number of partitions in the color difference diagram corresponding to the second value interval is greater than a third predetermined threshold, determining that the printed sample is unqualified, wherein the third predetermined threshold is greater than the first predetermined threshold;

[0107] (4) when the number of continuous partitions of the color in the color difference diagram corresponding to the second value interval is greater than a fourth predetermined threshold, determining that the printed sample is unqualified, wherein the fourth predetermined threshold is less than the third predetermined threshold;

[0108] (5) When the number of continuous partitions of the color corresponding to the third value interval in the color difference diagram is greater than a fifth predetermined threshold, the printed sample is determined to be unqualified, wherein the fifth predetermined threshold is less than the first predetermined threshold.

[0109] The above demonstration describes a typical example of evaluating the acceptability of a printed sample based on color distribution. Those skilled in the art will appreciate that this description is merely exemplary and is not intended to limit the scope of protection of the embodiments of the present invention.

[0110] The color contrast between the printed proof and the digital proof is different because the ink supply of the ink supply system for the four inks (yellow, red, blue and black) of the printing equipment is different when printing compared to the digital proof. In addition to increasing or decreasing the total ink supply of each color on the printing equipment, local increase or decrease adjustments can also be made through the ink supply channel of the printing equipment (the number of ink supply channels may be different for different models of printing equipment). The printing equipment usually has an adjustment table with a four-color total amount adjustment disk and a four-color ink supply adjustment disk for multiple ink supply channels. The four-color total amount can be adjusted through the four-color total amount adjustment disk, and the four-color ink supply of each ink supply channel can be adjusted separately through the four-color ink supply adjustment disk of each ink supply channel.

[0111] In one embodiment, Figure 1 The method shown includes: based on the overall color difference diagram, adjusting the total ink supply of each color among yellow, red, blue and black of the printing equipment of the printing sample; based on a part of the color difference diagram, adjusting the ink supply of each color among yellow, red, blue and black in the lower ink channel of the printing equipment corresponding to the part.

[0112] For example, when the overall color difference between the electronic parts of the digital proof and the electronic parts of the printed proof indicates that the printed proof is overall redder than the digital proof, the total amount of red ink supplied by the printing device is reduced. When the overall color difference between the electronic parts of the digital proof and the electronic parts of the printed proof indicates that the printed proof is overall yellower than the digital proof, the total amount of yellow ink supplied by the printing device is reduced.

[0113] For another example, when a certain local area of ​​the digital proof is redder than the local area of ​​the printed proof, the amount of red ink supplied in the ink channel corresponding to the local area in the printing device is reduced. When a certain local area of ​​the digital proof is yellower than the local area of ​​the printed proof, the amount of yellow ink supplied in the ink channel corresponding to the local area in the printing device is reduced.

[0114] Figure 5 is a structural diagram of a device for determining color differences of printed products according to an embodiment of the present invention. Figure 5 As shown, the device for determining the color difference of printed products includes: an acquisition module, used to acquire a first electronic part of a standard sample and a second electronic part of a printed sample; a partitioning module, used to partition the first electronic part and the second electronic part based on a predetermined size; a first determination module, used to determine the difference between the LAB value of each partition of the first electronic part and the LAB value of the corresponding partition of the second electronic part; a second determination module, used to determine the color of each partition based on the difference; and a third determination module, used to determine a color difference diagram representing the color difference between the standard sample and the printed sample based on the color of each partition.

[0115] In one embodiment, the color mode of the first electronic component and the second electronic component is an RGB color mode or a CMYK color mode; the first determination module is used to perform at least one of the following: calculate the first average RGB value or the first average CMYK value of all pixel points of each partition of the first electronic component; convert the first average RGB value or the first average CMYK value into the first average LAB value of each partition; calculate the second average RGB value or the second average CMYK value of all pixel points of the corresponding partition of the second electronic component; convert the second average RGB value or the second average CMYK value into the second average LAB value of the corresponding partition; determine the difference between the first average LAB value and the second average LAB value; convert the RGB value or CMYK value of each pixel point of each partition of the first electronic component into a LAB value; based on the first determination module, The third average LAB value of each partition of an electronic component is determined by the LAB value of each pixel point of each partition of the first electronic component; the RGB value or CMYK value of each pixel point of the corresponding partition of the second electronic component is converted into a LAB value; based on the LAB value of each pixel point of the corresponding partition of the second electronic component, the fourth average LAB value of the corresponding partition of the second electronic component is determined; the difference between the third average LAB value and the fourth average LAB value is determined; the RGB value or CMYK value of each pixel point of each partition of the first electronic component is converted into a LAB value; the RGB value or CMYK value of the corresponding pixel point of the corresponding partition of the second electronic component is converted into a LAB value; the average value of all differences between the LAB values ​​of all pixel points of each partition of the first electronic component and the LAB values ​​of the corresponding pixel points of the corresponding partition of the second electronic component is determined.

[0116] In one embodiment, the second determination module is used to determine the numerical interval to which the difference value of each partition belongs within a predetermined set of numerical intervals; and determine the color of each partition based on the corresponding relationship between the numerical interval and the predetermined color.

[0117] In one embodiment, the set of numerical intervals includes a first numerical interval, a second numerical interval, and a third numerical interval, wherein the maximum value of the first numerical interval is less than or equal to the minimum value of the second numerical interval, and the maximum value of the second numerical interval is less than or equal to the minimum value of the third numerical interval; the color of the partition includes at least one of the following: green; yellow; red; black.

[0118] In one embodiment, the device includes a processing module for statistically analyzing the color distribution in the color difference diagram; and evaluating the acceptability of the printed sample based on the color distribution.

[0119] In one embodiment, the processing module is used to perform at least one of the following: when the number of partitions in the color difference map corresponding to the third numerical interval is greater than the first predetermined threshold, the printed sample is determined to be unqualified; when the number of partitions in the color difference map corresponding to the first numerical interval is less than the second predetermined threshold, the printed sample is determined to be unqualified; when the number of partitions in the color difference map corresponding to the second numerical interval is greater than the third predetermined threshold, the printed sample is determined to be unqualified, wherein the third predetermined threshold is greater than the first predetermined threshold; when the number of continuous partitions in the color difference map corresponding to the second numerical interval is greater than the fourth predetermined threshold, the printed sample is determined to be unqualified, wherein the fourth predetermined threshold is less than the third predetermined threshold; when the number of continuous partitions in the color difference map corresponding to the third numerical interval is greater than the fifth predetermined threshold, the printed sample is determined to be unqualified, wherein the fifth predetermined threshold is less than the first predetermined threshold.

[0120] In one embodiment, the device includes a processing module for adjusting the total ink supply of each color of yellow, red, blue and black of a printing device for printing a sample based on the overall color difference diagram; and adjusting the ink supply of each color of yellow, red, blue and black in a lower ink channel of the printing device for printing a sample corresponding to the local part based on a local color difference diagram.

[0121] The embodiment of the present invention further provides an electronic device having a processor-memory architecture. Figure 6 is a structural diagram of an electronic device according to an embodiment of the present invention. Figure 6 As shown, the electronic device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, any of the above methods for determining the color difference of printed products is implemented. Among them, the memory can be implemented as a variety of storage media such as an electrically erasable programmable read-only memory (EEPROM), a flash memory (Flash memory), and a programmable program read-only memory (PROM). The processor can be implemented as including one or more central processing units or one or more field programmable gate arrays, wherein the field programmable gate array integrates one or more central processing unit cores. Specifically, the central processing unit or the central processing unit core can be implemented as a CPU, an MCU, or a DSP, etc.

[0122] It should be noted that not all steps and modules in the above-mentioned processes and structure diagrams are necessary, and some steps or modules can be ignored according to actual needs. The execution order of each step is not fixed and can be adjusted as needed. The division of each module is only for the convenience of describing the functional division adopted. In actual implementation, a module can be implemented by multiple modules, and the functions of multiple modules can also be implemented by the same module. These modules can be located in the same device or in different devices. The hardware modules in each embodiment can be implemented mechanically or electronically. For example, a hardware module can include a specially designed permanent circuit or logic device (such as a dedicated processor, such as FPGA or ASIC) for completing a specific operation. The hardware module can also include a programmable logic device or circuit (such as a general-purpose processor or other programmable processor) temporarily configured by software for performing a specific operation. As for the specific mechanical method, or the use of a dedicated permanent circuit, or the use of a temporarily configured circuit (such as configured by software) to implement the hardware module, it can be determined based on cost and time considerations.

[0123] The present invention also provides a machine-readable storage medium, storing instructions for making a machine perform a method as described in the present application. Specifically, a system or device equipped with a storage medium can be provided, on which a software program code for realizing the function of any of the embodiments in the above-mentioned embodiments is stored, and the computer (or CPU or MPU) of the system or device reads out and executes the program code stored in the storage medium. In addition, the operating system etc. operated on the computer can also be completed part or all of the actual operation by instructions based on the program code. The program code read out from the storage medium can also be written to the memory provided in the expansion board inserted into the computer or to the memory provided in the expansion unit connected to the computer, and then the CPU etc. installed on the expansion board or the expansion unit are made to perform part and all of the actual operation based on the instructions of the program code, so as to realize the function of any of the embodiments in the above-mentioned embodiments. The storage medium implementation for providing the program code includes a floppy disk, a hard disk, a magneto-optical disk, an optical disk (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), a magnetic tape, a non-volatile memory card and a ROM. Alternatively, the program code can be downloaded from a server computer or a cloud by a communication network.

[0124] In this article, "schematic" means "serving as an example, instance or explanation", and any diagram or implementation method described as "schematic" in this article should not be interpreted as a more preferred or more advantageous technical solution. In order to make the drawings concise, only the parts related to the present invention are schematically shown in each figure, and do not represent the actual structure of the product. In addition, in order to make the drawings concise and easy to understand, in some figures, only one of the parts with the same structure or function is schematically drawn, or only one of them is marked. In this article, "one" does not mean that the number of the relevant parts of the present invention is limited to "only one", and "one" does not mean that the number of the relevant parts of the present invention is "more than one". In this article, "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. are only used to indicate the relative position relationship between the relevant parts, rather than to limit the absolute position of these relevant parts.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining color differences of printed matter, characterized in that: include: Obtaining a first electronic copy of the standard proof and a second electronic copy of the printed proof; partitioning the first electronic component and the second electronic component based on a predetermined size; Determine the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component; Based on the difference, determining the color of each partition; Based on the color of each partition, a color difference diagram representing the color difference between the standard proof and the printed proof is determined.

2. The method according to claim 1, characterized in that: The color mode of the first electronic component and the second electronic component is RGB color mode or CMYK color mode; Determining the difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component includes at least one of the following: Calculate a first average RGB value or a first average CMYK value of all pixels of each partition of the first electronic component; convert the first average RGB value or the first average CMYK value into a first average LAB value of each partition; calculate a second average RGB value or a second average CMYK value of all pixels of a corresponding partition of the second electronic component; convert the second average RGB value or the second average CMYK value into a second average LAB value of the corresponding partition; determine a difference between the first average LAB value and the second average LAB value; Convert the RGB value or CMYK value of each pixel point of each partition of the first electronic component into a LAB value; determine the third average LAB value of each partition of the first electronic component based on the LAB value of each pixel point of each partition of the first electronic component; convert the RGB value or CMYK value of each pixel point of the corresponding partition of the second electronic component into a LAB value; determine the fourth average LAB value of the corresponding partition of the second electronic component based on the LAB value of each pixel point of the corresponding partition of the second electronic component; Determining a difference between the third average LAB value and the fourth average LAB value; Convert the RGB value or CMYK value of each pixel point of each partition of the first electronic component into a LAB value; convert the RGB value or CMYK value of the corresponding pixel point of the corresponding partition of the second electronic component into a LAB value; determine the average value of all differences between the LAB values ​​of all pixel points of each partition of the first electronic component and the LAB values ​​of the corresponding pixel points of the corresponding partition of the second electronic component.

3. The method according to claim 2, characterized in that The determining the color of each partition based on the difference comprises: Determine the numerical interval to which the difference value of each partition belongs within a predetermined set of numerical intervals; The color of each partition is determined based on the correspondence between the numerical range and the predetermined color.

4. The method according to claim 3, characterized in that The numerical interval set includes a first numerical interval, a second numerical interval and a third numerical interval, wherein the maximum value of the first numerical interval is less than or equal to the minimum value of the second numerical interval, and the maximum value of the second numerical interval is less than or equal to the minimum value of the third numerical interval; The color of the partition includes at least one of the following: Green; yellow; red; black.

5. The method according to claim 4, characterized in that include: Counting the color distribution in the color difference map; Based on the color distribution, the acceptability of the printed proof is evaluated.

6. The method according to claim 5, characterized in that The step of evaluating the acceptability of the printed proof based on the color distribution includes at least one of the following: When the number of partitions of the color in the color difference diagram corresponding to the third value interval is greater than a first predetermined threshold, determining that the printed sample is unqualified; When the number of partitions of the color in the color difference diagram corresponding to the first value interval is less than a second predetermined threshold, determining that the printed sample is unqualified; When the number of partitions in the color difference diagram corresponding to the second value interval is greater than a third predetermined threshold, determining that the printed sample is unqualified, wherein the third predetermined threshold is greater than the first predetermined threshold; When the number of continuous partitions of the color in the color difference diagram corresponding to the second value interval is greater than a fourth predetermined threshold, determining that the printed sample is unqualified, wherein the fourth predetermined threshold is less than the third predetermined threshold; When the number of continuous partitions of the colors in the color difference diagram corresponding to the third value interval is greater than a fifth predetermined threshold, the printed proof is determined to be unqualified, wherein the fifth predetermined threshold is less than the first predetermined threshold.

7. The method according to any one of claims 1 to 6, characterized in that include: Based on the entirety of the color difference diagram, adjusting the total ink supply of each color of yellow, red, blue and black by the printing device of the printing sample; Based on the part of the color difference diagram, the ink supply amount of each color of yellow, red, blue and black in the ink lower channel corresponding to the part of the printing device of the printing sample is adjusted.

8. A device for determining color differences of printed matter, characterized in that: include: An acquisition module, used for acquiring a first electronic copy of a standard sample and a second electronic copy of a printed sample; A partitioning module, configured to partition the first electronic component and the second electronic component based on a predetermined size; A first determination module, configured to determine a difference between the LAB value of each partition of the first electronic component and the LAB value of the corresponding partition of the second electronic component; A second determination module, configured to determine the color of each partition based on the difference; The third determination module is used to determine a color difference diagram representing the color difference between the standard sample and the printed sample based on the color of each partition.

9. An electronic device, characterized in that: include: processor; A memory, configured to store executable instructions of the processor; The processor is used to read the executable instructions from the memory and execute the executable instructions to implement the method for determining color differences of printed products according to any one of claims 1 to 7.

10. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the computer instructions are executed by a processor, the method for determining color differences of printed products according to any one of claims 1 to 7 is implemented.

11. A computer program product, characterized in that The invention comprises a computer program, which, when executed by a processor, implements the method for determining color differences of printed products according to any one of claims 1 to 7.

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