A printing control method and system for digital printing

Abstract

The present invention relates to the field of intelligent control technology, and in particular to a printing control method and system for digital printing, which are applied to a digital printing machine, wherein the digital printing machine includes a plurality of nozzles; the method includes: obtaining an original design image and a digital printing image, wherein the digital printing image is printed according to the original design image by a plurality of nozzles in the digital printing machine under different piezoelectric pressures; determining a regional image corresponding to each pixel point in the original design image in the digital printing image, and determining the color similarity of each regional image in the digital printing image; obtaining all colors contained in the original design image, determining a nozzle combination for digitally printing pixel points of each color, determining a target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity, and performing digital printing based on the target pressure value of each nozzle in the nozzle combination; the present invention can improve the printing accuracy of digital printing.

Description

Technical Field

[0001] The present invention relates to the field of intelligent control technology, and in particular to a printing control method and system for digital printing. Background Art

[0002] Digital printing is a printing method that uses digital technology. It uses digital image processing and printing technology to print the desired patterns and colors on textiles.

[0003] In the related technology, the patterns printed by digital printing still have color deviations. In order to obtain better color mixing effects, operators need to adjust printing parameters based on experience. This is not only inefficient, but also has a certain degree of randomness, making it difficult to fully meet the printing accuracy requirements of digital printing.

[0004] Therefore, it is necessary to provide a printing control method for digital printing, which can use intelligent control technology to improve the printing accuracy of digital printing. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a printing control method and system for digital printing, aiming to improve the printing accuracy of digital printing.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] On the one hand, an embodiment of the present invention provides a printing control method for digital printing, the method is applied to a digital printing machine, the digital printing machine includes a plurality of nozzles, each of the nozzles is used to spray ink of a different color;

[0008] The method comprises the following steps:

[0009] S100, obtaining an original design image and a digital printing image; wherein the digital printing image is printed according to the original design image by a plurality of nozzles in a digital printing machine under different piezoelectric pressures;

[0010] S200, determining the region image corresponding to each pixel point in the original design image in the digital print image, and determining the color similarity of each region image in the digital print image;

[0011] S300, acquiring all colors included in the original design image, determining a nozzle combination for digitally printing pixels of each color, and determining a target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity;

[0012] S400, performing digital printing based on the target pressure value of each nozzle in the nozzle combination.

[0013] Optionally, in S200, determining a region image corresponding to each pixel point in the original design image in the digital print image, and determining the color similarity of the digital print image based on the region image corresponding to each pixel point includes:

[0014] S210, determining a ratio value between the original design image and the digital print image, and performing region segmentation on the digital print image based on the ratio value to obtain a region image corresponding to each pixel point in the digital print image;

[0015] S220, grouping the pixels of the original design image that are the same color and adjacent to each other into one group, to obtain a plurality of groups of original pixel sets; wherein each group of the original pixel sets has a corresponding color;

[0016] S230, obtaining the number of pixel points in each group of the original pixel sets, and screening the original pixel sets whose number of pixel points is greater than a number threshold as the first pixel set;

[0017] S240, determining a regional image of each pixel in the first pixel set, and determining a color similarity of the first pixel set based on a grayscale value of the regional image.

[0018] Optionally, in S240, determining a regional image of each pixel in the first pixel set, and determining the color similarity of the first pixel set based on the grayscale value of the regional image includes:

[0019] S241, for a region image of each pixel point in the first pixel set, convert the region image into a grayscale image, divide the grayscale image into N×N grids, and determine a grayscale average value of each grid; wherein N is an integer greater than 2;

[0020] S242, calculating the grayscale difference of each grid in the regional image based on the grayscale average value of each grid in the regional image, and determining the color similarity of the regional image based on the grayscale difference and grayscale average value of each grid in the regional image.

[0021] Optionally, the color similarity of the regional image is calculated by the following formula:

[0022]

[0023] Where Gd is the minimum threshold of grayscale difference, Gs is the standard value of grayscale value; i, j are the numbers of grids, k is the total number of grids, i = 1, 2, ... k; Gd ij Gs is the grayscale difference between the i-th grid and the adjacent j-th grid. i is the grayscale value of the i-th grid; norml() represents the normalization process; Ca(p) represents the color approximation of the p-th region image.

[0024] Optionally, in S300, the acquiring of all colors included in the original design image, determining a nozzle combination for digitally printing pixels of each color, and determining a target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity includes:

[0025] S310, taking a plurality of first pixel sets whose color similarity is greater than a similarity threshold as second pixel sets, and determining a reference pressure value of each color based on the second pixel sets;

[0026] S320, dividing the color similarity into a plurality of similarity intervals, selecting a plurality of first pixel sets from each similarity interval as third pixel sets, and determining the pressure compensation relationship of each color based on the third pixel sets in each similarity interval; wherein the corresponding relationship represents the relationship between the compensation pressure value of each nozzle in the nozzle combination corresponding to the color and the similarity interval;

[0027] S330, adjusting the reference pressure value based on the pressure compensation relationship of each color to obtain a target pressure value of each color.

[0028] Optionally, in S310, determining the reference pressure value of each color based on the second pixel set includes:

[0029] S311, classifying each pixel point in the second pixel set according to the corresponding color, and determining the nozzle combination corresponding to each color;

[0030] S312, for each nozzle in the nozzle combination, obtaining the piezoelectric pressure when the nozzle prints each pixel corresponding to the color, averaging the piezoelectric pressure to obtain an average pressure value of the nozzle;

[0031] S313, the average pressure value of each nozzle in the nozzle combination is used to form a reference pressure value of the corresponding color.

[0032] Optionally, in S320, dividing the color similarity into a plurality of similarity intervals, selecting a plurality of first pixel sets from each similarity interval as the third pixel set, and determining the pressure compensation relationship of each color based on the third pixel set in each similarity interval includes:

[0033] S321, for each third pixel set in the similarity interval, selecting two adjacent pixels with different colors from the third pixel set as a pixel pair to obtain a plurality of pixel pairs;

[0034] S322, respectively determining the gradient values ​​of each grid in the regional image corresponding to the two pixel points in the pixel pair;

[0035] S323, selecting a pixel pair in sequence, for the regional image corresponding to the two pixel points in the pixel pair, determining the center point of the regional image, starting from the grid where the center point is located or an adjacent grid, traversing each grid in the regional image in sequence toward the edge of the regional image, screening grids whose gradient values ​​are less than the gradient threshold, and forming a valid area corresponding to the pixel point;

[0036] S324, determining the ratio of the effective area corresponding to the pixel point in the corresponding area image, forming a numerical set of the ratios of the pixel points corresponding to the color in each pixel pair, and determining whether there is a ratio with a value of 1 in the numerical set, and if so, recording the pixel point corresponding to the numerical set as the first pixel point, otherwise, recording it as the second pixel point;

[0037] S325, obtaining the second pixel points in each similarity interval, averaging the piezoelectric pressure of the nozzle corresponding to each second pixel point in the similarity interval, and obtaining the average pressure value corresponding to each similarity interval;

[0038] S326, arranging the approximation intervals in ascending order, calculating the difference between the average pressure values ​​corresponding to the current approximation interval and the next approximation interval, and obtaining the compensated pressure value of the current approximation interval;

[0039] S327, performing linear fitting on the compensation pressure value corresponding to each approximation interval to obtain a corresponding relationship between the approximation interval and the compensation pressure value as a pressure compensation relationship corresponding to the color of the second pixel point;

[0040] S328, determining whether each color forms a pressure compensation relationship, if not, executing S323; if yes, ending.

[0041] Optionally, in S330, adjusting the reference pressure value based on the pressure compensation relationship of each color to obtain a target pressure value of each color includes:

[0042] S331, averaging the color approximations of the pixels in the second pixel set to obtain a reference approximation;

[0043] S332, determining a compensation pressure value corresponding to the reference approximation based on the pressure compensation relationship;

[0044] S333: Taking the sum of the reference pressure value and the compensation pressure value as the target pressure value of the color.

[0045] On the other hand, an embodiment of the present invention provides a printing control system for digital printing, including:

[0046] at least one processor;

[0047] at least one memory for storing at least one program;

[0048] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0049] On the other hand, an embodiment of the present invention provides a computer-readable storage medium, in which a program executable by a processor is stored. When the program executable by the processor is executed by the processor, it is used to perform the above method.

[0050] The beneficial effects of the present invention are as follows: the present invention discloses a printing control method and system for digital printing, which obtains an original design image and a digital printing image printed by multiple nozzles in the digital printing machine under different piezoelectric pressures; determines the regional image corresponding to each pixel point in the original design image in the digital printing image, determines the color similarity of each regional image in the digital printing image; forms an index for evaluating the accuracy of digital printing; obtains all colors contained in the original design image, determines the nozzle combination for digitally printing the pixel points of each color, determines the target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity; controls each nozzle in the nozzle combination to perform digital printing according to the target pressure value. The present invention can improve the printing accuracy of digital printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0052] Figure 1 It is a flow chart of a printing control method for digital printing according to an embodiment of the present invention;

[0053] Figure 2 It is a structural schematic diagram of a printing control system for digital printing according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects disclosed in the present invention, so as to fully understand the purpose, scheme and effect disclosed in the present invention. It should be noted that the embodiments and features in the embodiments in this application can be combined with each other without conflict.

[0055] In digital printing machines, the overlapping of different colored inks from the nozzles will produce a mixed color effect. This is because digital printing machines usually use four basic colors of ink, CMYK (cyan, magenta, yellow, black), and through different combinations and overlaps of these colors, a wide range of colors can be produced. When these colors of ink are sprayed onto the fabric in different amounts and sequences, they mix to form new colors. For example, overlapping cyan and magenta inks can produce blue, overlapping yellow and magenta inks can produce red, and overlapping all three colors can produce black.

[0056] In actual applications, in order to improve production efficiency and printing quality, digital printing machines use a combination of nozzles with multiple colors. However, the printed patterns printed using the default printing parameters are often uneven in color; the reason for this phenomenon is that different colors of ink have corresponding ink expansion when applied to textile fabrics. The uneven color may be due to the inconsistent area of ​​ink dots formed by the ink sprayed by each nozzle after printing on the fabric, resulting in some areas not being mixed into the color corresponding to the pixel point.

[0057] In digital printing images, there will be a certain deviation between the regional image corresponding to the pixel and the target color. The present invention forms color approximation through quantification as a basis for judging the printing quality. The ink dot area can be adjusted by adjusting the piezoelectric pressure of the nozzle, so that the ink dot area corresponding to each nozzle is as consistent as possible, forming a color consistent with the pixel in the regional image.

[0058] refer to Figure 1 ,like Figure 1 A printing control method for digital printing provided by an embodiment of the present invention is shown, and the method is applied to a digital printing machine, and the digital printing machine includes a plurality of nozzles, and each nozzle is used to spray ink of a different color;

[0059] The method comprises the following steps:

[0060] S100, obtaining an original design image and a digital printing image; wherein the digital printing image is printed according to the original design image by a plurality of nozzles in a digital printing machine under different piezoelectric pressures;

[0061] Specifically, the digital printing machine includes a board card, the board card is provided with a plurality of nozzles, each nozzle is connected to a corresponding ink cartridge, each ink cartridge stores ink of a different color, and each nozzle is used to spray ink of a corresponding color. The digital printing image is obtained based on image acquisition of a digitally printed textile fabric, and the textile fabric is digitally printed based on the original design image; in some embodiments, the digital printing image is obtained by using a high-resolution industrial camera to acquire an image of the digitally printed textile fabric.

[0062] S200, determining the region image corresponding to each pixel point in the original design image in the digital print image, and determining the color similarity of each region image in the digital print image; wherein the color matching degree indicates the degree of similarity between the colors of each pixel point in the first pixel set and the corresponding region image;

[0063] It should be noted that since each pixel in the original design image is printed on the textile fabric, each pixel corresponds to at least one area. After the original design image is proportionally enlarged to be consistent with the digital print image, the pixels in the original design image are also enlarged. The enlarged pixels have corresponding areas in the digital print image. Since each pixel is of the same size, after being enlarged at the same proportion, the digital print image can be divided into multiple equal areas, thereby obtaining the regional image corresponding to each pixel, and determining the color similarity of each regional image in the digital print image as an indicator for evaluating the accuracy of digital printing.

[0064] S300, acquiring all colors included in the original design image, determining a nozzle combination for digitally printing pixels of each color, and determining a target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity;

[0065] Specifically, all colors corresponding to each pixel in the original design image are obtained, the same colors are classified into one category, and all colors contained in the original design image are obtained; the nozzle combination for digitally printing the pixel of each color and the corresponding regional image are determined, and the target pressure value of each nozzle in the nozzle combination corresponding to each color is determined based on the color similarity of the regional image.

[0066] S400, performing digital printing based on the target pressure value of each nozzle in the nozzle combination.

[0067] Specifically, the color corresponding to each pixel in the original design image is obtained, and each nozzle in the nozzle combination corresponding to the color is controlled to perform digital printing according to the target pressure value, thereby printing out the area image corresponding to each pixel in the original design image, forming a digital printing image with higher printing accuracy.

[0068] The present invention quantifies the color similarity of each regional image in a digital printing image; determines the target pressure value of each nozzle in a corresponding nozzle combination based on the color similarity; and controls each nozzle in the nozzle combination to print using the corresponding target pressure value, thereby achieving a high-quality printing effect.

[0069] In some embodiments, in S200, determining a region image corresponding to each pixel point in the original design image in the digital print image, and determining the color similarity of the digital print image based on the region image corresponding to each pixel point includes:

[0070] S210, determining a ratio value between the original design image and the digital print image, and performing region segmentation on the digital print image based on the ratio value to obtain a region image corresponding to each pixel point in the digital print image;

[0071] Specifically, the original design image is enlarged to a size consistent with the size of the digital print image, each pixel in the original design image is enlarged based on the ratio value, the minimum enclosing rectangle of the enlarged pixel is determined, and the digital print image is segmented into regions based on the minimum enclosing rectangle to obtain the regional image corresponding to each pixel.

[0072] S220, grouping the pixels of the original design image that are the same color and adjacent to each other into one group, to obtain a plurality of groups of original pixel sets; wherein each group of the original pixel sets has a corresponding color;

[0073] Specifically, for each pixel in the original design image, the 8-neighborhood pixel points of the pixel are queried, connected with the pixel points with the same color value (such as grayscale value), and each pixel point is traversed in turn, and the connected pixel points are taken as a pixel set to obtain multiple groups of pixel sets; the pixels in a pixel set have the same color.

[0074] S230, obtaining the number of pixel points in each group of the original pixel sets, and screening the original pixel sets whose number of pixel points is greater than a number threshold as the first pixel set;

[0075] Specifically, if there are too few pixels in the original pixel set, the original pixel set is not representative and will affect the effectiveness of subsequent processing steps. In this embodiment, the quantity threshold is set to at least 3; for example, it is set to 3 to 20 according to actual conditions, and at least 6 first pixel sets are screened out. The larger the quantity threshold, the more pixels the screened first pixel set contains, and the more representative the corresponding color is.

[0076] S240, determining a regional image of each pixel point in the first pixel set, and determining a color similarity of the first pixel set based on a grayscale value of the regional image; wherein the color matching degree indicates a degree of similarity between the colors of each pixel point in the first pixel set and the corresponding regional image;

[0077] Specifically, the color similarity of each first pixel set is first calculated, and the printing effect of each first pixel set can be obtained as a whole. If the color similarity is high, it means that the color restoration of the image in the corresponding area is good. The corresponding first pixel set can be used as the result of preliminary screening, thereby forming a benchmark pixel set later.

[0078] In some embodiments, in S240, determining a regional image of each pixel in the first pixel set, and determining the color similarity of the first pixel set based on the grayscale value of the regional image includes:

[0079] S241, for a region image of each pixel point in the first pixel set, convert the region image into a grayscale image, divide the grayscale image into N×N grids, and determine a grayscale average value of each grid; wherein N is an integer greater than 2;

[0080] It should be noted that when multiple nozzles print the area corresponding to the same pixel point in a set order, due to the uneven area of ​​the ink dots, the ink dot area of ​​some nozzles will be larger, thus occupying the area of ​​other pixel points, causing the color of the image of the corresponding area of ​​other pixel points to change; the ink dot area of ​​some nozzles is smaller, resulting in the edge part of the corresponding area not being printed, resulting in color mismatch. This embodiment evaluates the regional image of each pixel point based on the grayscale value to obtain the color similarity, which can comprehensively reflect the printing quality of the pixel points in the first pixel set, and then determine the color corresponding to the first pixel set. After obtaining all the nozzles corresponding to the color, it is used as an evaluation indicator reflecting the printing quality of the corresponding nozzle.

[0081] S242, calculating the grayscale difference of each grid in the regional image based on the grayscale average value of each grid in the regional image, and determining the color similarity of the regional image based on the grayscale difference and grayscale average value of each grid in the regional image.

[0082] Specifically, the grayscale difference is the grayscale difference between the grid and the grid in its domain; the grayscale difference and grayscale average of each grid are combined and compared with the grayscale value of the corresponding color of the grid, which not only reflects the consistency of the color, but also reflects the difference in color, and overall reflects the similarity of the colors.

[0083] In some embodiments, the color similarity of the region image is calculated by the following formula:

[0084]

[0085] Where Gd is the minimum threshold of grayscale difference, Gs is the standard value of grayscale value; i, j are the numbers of grids, k is the total number of grids, i = 1, 2, ... k; Gd ijGs is the grayscale difference between the i-th grid and the adjacent j-th grid. i is the grayscale value of the i-th grid; norml() represents the normalization process; Ca(p) represents the color approximation of the p-th region image.

[0086] It should be noted that the standard value of the grayscale value Gs represents the grayscale value of the pixel color corresponding to the image in the area; the smaller the difference between the grayscale value of the grid and the standard value, the more similar the colors are, and the greater the value of the color similarity; max(Gd ij ) represents the maximum grayscale difference of the i-th grid. If the maximum grayscale difference max(Gd ij ) is less than the minimum grayscale difference threshold Gd, it means that the grayscale consistency of the regional image is good and the color approximation can be improved; if the maximum grayscale difference max(Gd ij ) is greater than the minimum grayscale difference threshold Gd, it means that the color change is obvious, so the color similarity is reduced.

[0087] In some embodiments, in S300, the obtaining of all colors included in the original design image, determining a nozzle combination for digitally printing pixels of each color, and determining a target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity include:

[0088] S310, taking a plurality of first pixel sets whose color similarity is greater than a similarity threshold as second pixel sets, and determining a reference pressure value of each color based on the second pixel sets;

[0089] Specifically, since the printed color has a certain tolerance, based on this, a suitable similarity threshold can be set to filter out the second pixel set that meets the tolerance requirement, and also ensure that the filtered second pixel set has a certain printing quality, which facilitates subsequent processing of an effective reference pressure value.

[0090] S320, dividing the color similarity into a plurality of similarity intervals, selecting a plurality of first pixel sets from each similarity interval as third pixel sets, and determining the pressure compensation relationship of each color based on the third pixel sets in each similarity interval; wherein the corresponding relationship represents the relationship between the compensation pressure value of each nozzle in the nozzle combination corresponding to the color and the similarity interval;

[0091] S330, adjusting the reference pressure value based on the pressure compensation relationship of each color to obtain a target pressure value of each color. In some embodiments, in S310, determining the reference pressure value of each color based on the second pixel set includes:

[0092] S311, classifying each pixel point in the second pixel set according to the corresponding color, and determining the nozzle combination corresponding to each color;

[0093] S312, for each nozzle in the nozzle combination, obtaining the piezoelectric pressure when the nozzle prints each pixel corresponding to the color, averaging the piezoelectric pressure to obtain an average pressure value of the nozzle;

[0094] S313, the average pressure value of each nozzle in the nozzle combination is used to form a reference pressure value of the corresponding color.

[0095] Specifically, when the printing parameters of the nozzle are limited, the color similarity is used as the judgment basis to select the regional image with the highest printing accuracy to form a reference image, and then the nozzle combination corresponding to the reference image and the piezoelectric pressure of each nozzle in the nozzle combination are statistically calculated as the reference piezoelectric pressure, and this is used as the control parameter of the nozzle, so as to maximize the performance of the nozzle and improve printing accuracy.

[0096] In some embodiments, in S320, dividing the color similarity into a plurality of similarity intervals, selecting a plurality of first pixel sets from each similarity interval as the third pixel set, and determining the pressure compensation relationship of each color based on the third pixel set in each similarity interval includes:

[0097] S321, for each third pixel set in the similarity interval, selecting two adjacent pixels with different colors from the third pixel set as a pixel pair to obtain a plurality of pixel pairs;

[0098] Specifically, the pixels in the second pixel set are combined in groups of two to obtain multiple pixel pairs, and the pixels in each pixel pair are adjacent and have different colors. Selecting pixels of different colors can increase contrast and facilitate subsequent search for effective areas.

[0099] S322, respectively determining the gradient values ​​of each grid in the regional image corresponding to the two pixel points in the pixel pair;

[0100] S323, selecting a pixel pair in sequence, for the regional image corresponding to the two pixel points in the pixel pair, determining the center point of the regional image, starting from the grid where the center point is located or an adjacent grid, traversing each grid in the regional image in sequence toward the edge of the regional image, screening grids whose gradient values ​​are less than the gradient threshold, and forming a valid area corresponding to the pixel point;

[0101] It should be noted that each pixel pair can be selected in sequence from left to right and from top to bottom. The center point of the regional image corresponding to the two pixels in the pixel pair may be the intersection of the grids or the center of the grids. After respectively determining the gradient value of each grid in the regional image corresponding to the pixel point, the grid related to the center point is taken as the starting point to determine whether the gradient value of the grid is less than the gradient threshold. If the gradient value of the grid is less than the gradient threshold, the grid is used as a candidate grid, and then the neighborhood grids of the candidate grid are selected to determine in sequence whether the gradient value of each grid is less than the gradient threshold. After there is no grid with a gradient value less than the gradient threshold in the neighborhood grids of the candidate grid, the traversal is terminated, and the grids with gradient values ​​less than the gradient threshold form a valid area.

[0102] It should be noted that the smaller the gradient value, the smaller the color change in the regional image, and the color of the regional image is closer to the target color as a whole. Based on the printing accuracy requirements, a suitable gradient threshold can be set to screen the regional images. If the regional images with gradient values ​​less than the gradient threshold can be screened out, they can be combined to form a valid area.

[0103] S324, determining the ratio of the effective area corresponding to the pixel point in the corresponding area image, forming a numerical set of the ratios of the pixel points corresponding to the color in each pixel pair, and determining whether there is a ratio with a value of 1 in the numerical set, and if so, recording the pixel point corresponding to the numerical set as the first pixel point, otherwise, recording it as the second pixel point;

[0104] Specifically, the effective area and regional image corresponding to the pixel point are determined, and the proportion of the effective area in the corresponding regional image is taken as the ratio corresponding to the pixel point; the value range of the ratio is (0,1]. If the ratio is 1, it means that when printing the pixel point, the piezoelectric pressure of the nozzle is too large, resulting in complete coverage of the image area corresponding to the pixel point, and it is very likely to cover other image areas and cannot be used for subsequent calculations. Since the digital printing image is printed by multiple nozzles under different piezoelectric pressures, it can be guaranteed that a sufficient number of second pixels are screened out.

[0105] S325, obtaining the second pixel points in each similarity interval, averaging the piezoelectric pressure of the nozzle corresponding to each second pixel point in the similarity interval, and obtaining the average pressure value corresponding to each similarity interval;

[0106] S326, arranging the approximation intervals in ascending order, calculating the difference between the average pressure values ​​corresponding to the current approximation interval and the next approximation interval, and obtaining the compensated pressure value of the current approximation interval;

[0107] Specifically, the average pressure values ​​corresponding to two adjacent approximation intervals are sequentially subtracted to obtain a pressure difference value corresponding to each approximation interval as a compensation pressure value.

[0108] S327, performing linear fitting on the compensation pressure value corresponding to each approximation interval to obtain a corresponding relationship between the approximation interval and the compensation pressure value as a pressure compensation relationship corresponding to the color of the second pixel point;

[0109] Specifically, after each similarity interval obtains the corresponding average pressure value, the corresponding average pressure value can be matched by searching the similarity interval where the color similarity of the regional image is located.

[0110] S328, determining whether each color forms a pressure compensation relationship, if not, executing S323; if yes, ending.

[0111] In some embodiments, in S330, adjusting the reference pressure value based on the pressure compensation relationship of each color to obtain the target pressure value of each color includes:

[0112] S331, averaging the color approximations of the pixels in the second pixel set to obtain a reference approximation;

[0113] S332, determining a compensation pressure value corresponding to the reference approximation based on the pressure compensation relationship;

[0114] Specifically, after determining the similarity interval in which the reference similarity is located, the compensation pressure value corresponding to the similarity interval is used as the compensation pressure value corresponding to the reference similarity;

[0115] S333: Taking the sum of the reference pressure value and the compensation pressure value as the target pressure value of the color.

[0116] In this embodiment, since the color similarity of the second pixel set is relatively high, it is difficult to directly determine the corresponding compensation pressure value; by establishing a pressure compensation relationship for the corresponding colors, the compensation pressure value corresponding to the reference similarity is determined using the pressure compensation relationship, and combined with the reference pressure value, a more accurate target pressure value is obtained, thereby further improving printing accuracy.

[0117] refer to Figure 2 The embodiment of the present invention further provides a printing control system for digital printing, including:

[0118] at least one processor;

[0119] at least one memory for storing at least one program;

[0120] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0121] The contents of the above method embodiments are all applicable to this embodiment. The functions specifically implemented by this embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments, which will not be repeated here.

[0122] Although the description of the present disclosure has been quite detailed and specifically describes several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation of these claims by reference to the appended claims, taking into account the prior art, so as to effectively cover the intended scope of the present disclosure. In addition, the above description of the present disclosure is based on the embodiments foreseeable by the inventor, and its purpose is to provide a useful description, and those non-substantial changes to the present disclosure that have not yet been foreseen may still represent equivalent changes to the present disclosure.

Claims

1. A printing control method for digital printing, characterized in that: The method is applied to a digital printing machine, which includes a plurality of nozzles; the method includes the following steps: S100, obtaining an original design image and a digital printing image; wherein the digital printing image is printed according to the original design image by a plurality of nozzles in a digital printing machine under different piezoelectric pressures; S200, determining the region image corresponding to each pixel point in the original design image in the digital print image, and determining the color similarity of each region image in the digital print image; S300, acquiring all colors included in the original design image, determining a nozzle combination for digitally printing pixels of each color, and determining a target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity; S400, performing digital printing based on the target pressure value of each nozzle in the nozzle combination; In S200, determining the region image corresponding to each pixel point in the original design image in the digital print image, and determining the color similarity of the digital print image based on the region image corresponding to each pixel point includes: S210, determining a ratio value between the original design image and the digital print image, and performing region segmentation on the digital print image based on the ratio value to obtain a region image corresponding to each pixel point in the digital print image; S220, grouping the pixels of the original design image that are the same color and adjacent to each other into one group, to obtain a plurality of groups of original pixel sets; wherein each group of the original pixel sets has a corresponding color; S230, obtaining the number of pixel points in each group of the original pixel sets, and screening the original pixel sets whose number of pixel points is greater than a number threshold as the first pixel set; S240, determining a regional image of each pixel in the first pixel set, and determining a color similarity of the first pixel set based on a grayscale value of the regional image; In S240, determining the regional image of each pixel point in the first pixel set, and determining the color similarity of the first pixel set based on the grayscale value of the regional image includes: S241, for a region image of each pixel point in the first pixel set, convert the region image into a grayscale image, divide the grayscale image into N×N grids, and determine a grayscale average value of each grid; wherein N is an integer greater than 2; S242, calculating a grayscale difference value of each grid in the regional image based on the grayscale average value of each grid in the regional image, and determining a color similarity of the regional image based on the grayscale difference value and the grayscale average value of each grid in the regional image; The color similarity of the regional image is calculated by the following formula: ； Wherein, Gd is the minimum threshold of grayscale difference, Gs is the standard value of grayscale value; i, j are the numbers of grids, k is the total number of grids, i=1, 2, ..., k; is the grayscale difference between the ith grid and the adjacent jth grid, is the grayscale value of the i-th grid; norml() represents the normalization process; Ca(p) represents the color approximation of the p-th region image.

2. A digital printing control method according to claim 1, characterized in that: In S300, the step of acquiring all colors included in the original design image, determining a nozzle combination for digitally printing pixels of each color, and determining a target pressure value of each nozzle in the nozzle combination corresponding to each color based on the color similarity includes: S310, taking a plurality of first pixel sets whose color similarity is greater than a similarity threshold as second pixel sets, and determining a reference pressure value of each color based on the second pixel sets; S320, dividing the color similarity into a plurality of similarity intervals, selecting a plurality of first pixel sets from each similarity interval as third pixel sets, and determining the pressure compensation relationship of each color based on the third pixel sets in each similarity interval; wherein the corresponding relationship represents the relationship between the compensation pressure value of each nozzle in the nozzle combination corresponding to the color and the similarity interval; S330, adjusting the reference pressure value based on the pressure compensation relationship of each color to obtain a target pressure value of each color.

3. A digital printing control method according to claim 2, characterized in that: In S310, determining the reference pressure value of each color based on the second pixel set includes: S311, classifying each pixel point in the second pixel set according to the corresponding color, and determining the nozzle combination corresponding to each color; S312, for each nozzle in the nozzle combination, obtaining the piezoelectric pressure when the nozzle prints each pixel corresponding to the color, averaging the piezoelectric pressure to obtain an average pressure value of the nozzle; S313, the average pressure value of each nozzle in the nozzle combination is used to form a reference pressure value of the corresponding color.

4. A digital printing control method according to claim 2, characterized in that: In S320, the color similarity is equally divided into a plurality of similarity intervals, a plurality of first pixel sets are respectively selected from each similarity interval as the third pixel set, and the pressure compensation relationship of each color is determined based on the third pixel set in each similarity interval, including: S321, for each third pixel set in the similarity interval, selecting two adjacent pixels with different colors from the third pixel set as a pixel pair to obtain a plurality of pixel pairs; S322, respectively determining the gradient values ​​of each grid in the regional image corresponding to the two pixel points in the pixel pair; S323, selecting a pixel pair in sequence, for the regional image corresponding to the two pixel points in the pixel pair, determining the center point of the regional image, starting from the grid where the center point is located or an adjacent grid, traversing each grid in the regional image in sequence toward the edge of the regional image, screening grids whose gradient values ​​are less than the gradient threshold, and forming a valid area corresponding to the pixel point; S324, determining the ratio of the effective area corresponding to the pixel point in the corresponding area image, forming a numerical set of the ratios of the pixel points corresponding to the color in each pixel pair, and determining whether there is a ratio with a value of 1 in the numerical set, and if so, recording the pixel point corresponding to the numerical set as the first pixel point, otherwise, recording it as the second pixel point; S325, obtaining the second pixel points in each similarity interval, averaging the piezoelectric pressure of the nozzle corresponding to each second pixel point in the similarity interval, and obtaining the average pressure value corresponding to each similarity interval; S326, arranging the approximation intervals in ascending order, calculating the difference between the average pressure values ​​corresponding to the current approximation interval and the next approximation interval, and obtaining the compensated pressure value of the current approximation interval; S327, performing linear fitting on the compensation pressure value corresponding to each approximation interval to obtain a corresponding relationship between the approximation interval and the compensation pressure value as a pressure compensation relationship corresponding to the color of the second pixel point; S328, determining whether each color forms a pressure compensation relationship, if not, executing S323; if yes, ending.

5. A digital printing control method according to claim 2, characterized in that: In S330, adjusting the reference pressure value based on the pressure compensation relationship of each color to obtain the target pressure value of each color includes: S331, averaging the color approximations of the pixels in the second pixel set to obtain a reference approximation; S332, determining a compensation pressure value corresponding to the reference approximation based on the pressure compensation relationship; S333: Taking the sum of the reference pressure value and the compensation pressure value as the target pressure value of the color.

6. A digital printing control system, characterized in that: include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method according to any one of claims 1 to 5.

7. A computer-readable storage medium storing a program executable by a processor, characterized in that: The processor-executable program is used to perform the method according to any one of claims 1 to 5 when executed by the processor.

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