Method, device and storage medium for color calibration of channels within the same printhead

Abstract

The present invention discloses a method, device and storage medium for color calibration of channels within the same nozzle. The method includes the following steps: S1, obtaining a color calibration pattern and importing it into a printer system; S2, printing the color calibration pattern; S3, entering the color calibration pattern printed in step S2 into image processing software; S4, importing the color calibration pattern of step S1 into the image processing software; S5, comparing the color calibration pattern entered in step S3 with the color calibration pattern imported in step S4 and calibrating the control parameters of the printer system according to the comparison result. The present invention solves the problem that the prior art cannot effectively calibrate the errors of upper and lower offset color calibration between channels within the nozzle, and can simultaneously calibrate the left and right and upper and lower color calibration errors between nozzles, thereby improving calibration efficiency. In addition, the calibration chart of the present invention can be output to any resolution, so it can adapt to printing requirements of different resolutions, thereby greatly improving the calibration accuracy and print quality of the printer.

Description

Technical Field

[0001] The present invention relates to the technical field of printers, and in particular to a method, a device and a storage medium for color registration calibration of channels within a same nozzle. Background Art

[0002] Conventional printhead channel color calibration typically uses a simple calibration pattern with thick and thin vertical lines to form a simple calibration element and a reference element, respectively. The calibration pattern's resolution is typically set to the printer's base resolution. During production, the resolution of printed images is often an integer multiple of the printer's base resolution. This can lead to inaccurate calibration due to assembly or processing errors, and it can't correct for errors in color registration between channels within the printhead.

[0003] Traditional printhead intra-channel color calibration relies primarily on calibration primitives consisting of thick and thin vertical lines, with the resolution of the calibration image fixed to the printer's base resolution. This method has limitations when calibrating high-resolution print jobs and cannot fully adapt to varying resolution requirements, resulting in limited calibration accuracy.

[0004] The existing technology cannot effectively calibrate the errors of the upper and lower offset colors between the channels in the nozzle, and the calibration effect is poor when printing at non-base resolutions, affecting the print quality. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a method, a device and a storage medium for color calibration of channels within the same printhead.

[0006] The technical solution of the present invention is achieved as follows:

[0007] A method for color registration calibration of channels within a same printhead comprises the following steps:

[0008] S1, obtaining a color calibration pattern and importing it into a printer system;

[0009] S2, according to step S1, printing a color calibration pattern;

[0010] S3, inputting the color calibration pattern printed in step S2 into the image processing software;

[0011] S4, importing the color calibration pattern of step S1 into the image processing software;

[0012] S5, comparing the color calibration pattern entered in step S3 with the color calibration pattern imported in step S4 and calibrating the control parameters of the printer system according to the comparison result;

[0013] Preferably, in step S1, the color calibration pattern is specifically a plurality of groups of patterns consisting of a plurality of large squares, small squares and color squares in a grid format, wherein the color squares are placed in the middle of the small squares, and the small squares are placed in the middle of the large squares, and adjustment parameters of the same size as in the printer system are set below each group of patterns.

[0014] Preferably, the step S3 is specifically to scan the color calibration pattern printed out in step S2 completely and enter it into the image processing software, and adjust the size of the entered color calibration pattern in the image processing software.

[0015] A device for color calibration of channels within the same printhead includes at least one processor, at least one memory, and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, an acquisition method for color calibration of channels within the same printhead is implemented.

[0016] A storage medium stores computer program instructions, which, when executed by a processor, implement the above-mentioned method for color registration calibration of channels within the same printhead.

[0017] The present invention solves the problem that the existing technology cannot effectively calibrate the errors of upper and lower offset color registration between channels in the nozzle. It can simultaneously calibrate the left and right and upper and lower color registration errors between nozzles, thereby improving the calibration efficiency. In addition, the calibration chart of the present invention can be output to any resolution, so it can adapt to printing requirements of different resolutions, thereby greatly improving the calibration accuracy and printing quality of the printer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a method for color calibration of channels within the same printhead according to the present invention.

[0019] Figure 2 The present invention is a schematic diagram of a color calibration pattern for a method of color calibration of channels within the same nozzle. DETAILED DESCRIPTION

[0020] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present application. Rather, they are merely examples of methods and systems consistent with certain aspects of the present application, as detailed in the appended claims.

[0021] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0022] Example 1

[0023] like Figure 1 and Figure 2 As shown, the present invention provides a method for color calibration of channels within the same printhead, comprising the following steps:

[0024] S1, obtaining a color calibration pattern and importing it into a printer system;

[0025] Preferably, in step S1, the color calibration pattern is specifically a plurality of groups of patterns consisting of a plurality of large squares, small squares and color squares in a grid format, wherein the color square is placed in the middle of the small square, and the small square is placed in the middle of the large square, and adjustment parameters of the same size as those in the printer system are provided below each group of patterns. The four lines of the large square can be adjusted to different line thicknesses for more intuitive calibration in the horizontal and vertical directions. The color square is selected from high-contrast colors such as cyan, magenta, yellow or black, with a side length of approximately 1-2 mm, and is placed in the center of the small square. In the original calibration pattern, the small square is completely filled to facilitate subsequent comparison.

[0026] S2, according to step S1, printing a color calibration pattern;

[0027] Preferably, in step S2, before printing, a print preview image is captured to determine the specific position of the color calibration pattern on the printing paper. Specifically, the coordinate parameters of the four corners of the color calibration pattern are obtained with the center of the printing paper as the center point. After the print preview image is captured before printing, in addition to obtaining the coordinate parameters of the four corners of the color calibration pattern, the color distribution histogram of the preview image is also simultaneously analyzed to estimate in advance the areas where color deviation may occur, providing a reference for the focus of subsequent calibration. At the same time, the coordinate parameters are mapped and associated with the physical position of the printer nozzle to assist in determining the potential deviation of the nozzle when moving horizontally and vertically on the paper.

[0028] Before starting printing, use the printer's built-in preview function or professional print management software to capture a print preview image with a resolution of at least 300 dpi. Using the geometric center of the printing paper as the origin, apply a high-precision image analysis algorithm to obtain the coordinate parameters of the four corners of the color calibration pattern, maintaining an error within ±0.05 mm. Simultaneously, use a color analysis plug-in to analyze the preview image's color distribution histogram, observing the peaks and distribution of each color channel and estimating areas of color deviation. Furthermore, carefully map the coordinate parameters to the physical layout of the printer's printheads and correlate their movement. Finally, select the appropriate paper and ink and begin printing.

[0029] S3, inputting the color calibration pattern printed in step S2 into the image processing software;

[0030] Preferably, the step S3 is specifically to scan the color calibration pattern printed out in step S2 completely and enter it into the image processing software, and adjust the size of the entered color calibration pattern in the image processing software.

[0031] Preferably, the step S3 is specifically to scan the color calibration pattern printed out in step S2 completely and enter it into the image processing software, and adjust the size of the entered color calibration pattern in the image processing software.

[0032] Using a scanner with at least 600 dpi accuracy, completely import the printed pattern into professional image processing software, such as Adobe Photoshop or CorelDRAW. Enable the Intelligent Edge Detection tool to capture the edge information of the imported pattern. Then, the paper edge parameters are obtained from the paper specifications or printer driver, accurate to 0.01 mm, and the imported pattern edges are scaled accordingly. The software displays the scale ratio in real time and automatically records the adjustment value. Repeat this process until the difference between the imported pattern and the paper edge parameters is within 0.01 mm. High scanning accuracy preserves original details, and intelligent detection accurately locates edges. Scaling based on the actual paper parameters can correct dimensional deviations caused by scanning and paper deformation. Recording the values ​​facilitates tracing back issues.

[0033] S4, importing the color calibration pattern of step S1 into the image processing software;

[0034] S5, comparing the color calibration pattern entered in step S3 with the color calibration pattern imported in step S4 and calibrating the control parameters of the printer system according to the comparison result;

[0035] Preferably, in step S1, in addition to multiple groups of patterns consisting of a grid of multiple large and small squares and color blocks, each color block can be selected from colors that are sharply contrasting and commonly found in the print color gamut, such as basic colors like cyan, magenta, yellow, and black, to enhance visual recognition. At the same time, a small blank area is reserved around each group of patterns to prevent color interference that affects subsequent image recognition. The adjustment parameters set below the pattern not only include size information but also additionally indicate the corresponding nozzle channel number to facilitate quick location of the problem channel.

[0036] Preferably, the step of resizing the input color calibration pattern in the image processing software comprises the following steps:

[0037] L1, obtain the edge information of the recorded color calibration pattern;

[0038] L2, obtain the edge parameters of the printing paper;

[0039] L3, adjust the edge parameters of the entered color calibration pattern in the same proportion as the edge parameters of the printing paper;

[0040] L4, repeat steps L1-L3 until the edge parameters of the recorded color calibration pattern are exactly the same as the edge parameters of the printing paper.

[0041] Preferably, the operation steps of step S5 in the image processing software are as follows:

[0042] Q1: Adjust the transparency of the color calibration pattern imported in step S4 to 50-70%. In your image processing software, select the original imported color calibration pattern layer and, using the Layer Properties panel, drag the transparency slider or enter a value to precisely adjust the transparency to the 50-70% range. After multiple tests, 50% transparency allows the underlying pattern to clearly show through, while 70% ensures visual contrast while highlighting underlying details, facilitating subsequent operations.

[0043] Q2, place the color calibration pattern obtained in step Q1 at the location of the print preview in step S2. Use the move tool of the image processing software and the coordinate parameters obtained in step S2 to accurately place the original color calibration pattern with adjusted transparency to the corresponding location in the print preview, ensuring that the two are initially aligned in space.

[0044] Q3, place the color calibration pattern obtained in step S3 to the print preview position in step S2, and use the move tool to move the actual printed pattern to the same print preview position as the original pattern in the previous step, ready for difference comparison;

[0045] In Q4, the two patterns from steps Q2 and Q3 are identified and compared using image recognition methods. Using deep learning image recognition methods, a recognition model specifically tailored to the characteristics of this color calibration pattern is trained. Compared to traditional algorithms, the accuracy of recognizing subtle pattern displacements and color deviations is improved by over 30%. During the recognition and comparison process, a comparison heat map is generated in real time to visually display the difference distribution between the two patterns.

[0046] Q5, output comparison results. When comparing the entered color calibration pattern with the imported color calibration pattern, in addition to using the coordinate parameter difference before and after movement as the basis for adjusting the control parameters of the printer system, the color deviation value when the color block fills the small square is also comprehensively considered. The software system organizes the comparison data, accurately calculates the coordinate displacement difference of the entered pattern relative to the original pattern in the horizontal and vertical directions, and quantifies the color deviation when the color block fills the small square to form a detailed comparison report.

[0047] Preferably, the comparison result in step Q5 is specifically to compare each group of patterns in the recorded color calibration pattern and the imported color calibration pattern, take the imported color calibration pattern as the standard, completely overlap the large square of the recorded color calibration pattern, hide the small square of the recorded color calibration pattern, extract the color square of the recorded color calibration pattern and place it in the small square of the imported color calibration pattern until the small square is completely filled with the color square, and use the difference between the coordinate parameters before and after the movement as the basis for adjusting the control parameters of the printer system.

[0048] More optimally, when analyzing the comparison results in step Q5, an image segmentation algorithm is used to precisely subdivide the color calibration pattern into numerous tiny areas according to the logical structure of the pattern, with a combination of large squares, small squares, and color blocks as the basic units. For each unit, a moment-based method is used to determine the geometric center. For a discrete set of pixel points (constituting pattern units), the zero-order moment can be used to calculate the area of ​​the region, and the first-order moment is used to determine the center of gravity coordinates. By comparing the center of gravity coordinates of the same unit in the recorded pattern and the imported pattern, the horizontal error Δx and vertical error Δy are obtained. For a small square color block combination unit, the center of gravity coordinates in the recorded pattern are (x1, y1), and in the imported pattern are (x2, y2). Then the horizontal error Δx = x2 - x1, and the vertical error Δy = y2 - y1. In this way, the displacement error of the overall pattern is broken down into its key components, avoiding information omissions caused by general calculations.

[0049] In color deviation analysis, we convert to the LAB color space, which simulates human visual perception and makes color difference evaluation more consistent with actual visual effects. For each color square, the LAB value is extracted from the image color model. Assume that the LAB value of the input pattern color square is (L1, a1, b1), and the corresponding square of the imported pattern is (L2, a2, b2). The lightness difference ΔL = L2-L1, the chromaticity difference Δa = a2-a1, and the hue difference Δb = b2-b1. The differences in these three dimensions fully describe the color deviation. Whether it is the subsequent correction of single color deviation or the adjustment of complex color combinations, there is accurate data support.

[0050] In-depth research on the characteristics of printing tasks shows that in the case of business document printing, the neatness and clarity of the text are the primary considerations. The horizontal color registration accuracy is directly related to the text line spacing and character spacing, so the horizontal displacement error weight w x It can be set to 0.6, the vertical displacement error weight w y Set to 0.4, and the total color deviation weight is set to 0. For art poster printing, color reproduction is extremely important. Brightness, chroma, and hue are related to the layering and visual impact of the picture. x 、w y Each is set to 0.2, w L 、w a 、w b Set to 0.2 respectively.

[0051] Construct the weighted error calculation formula E=w x Δx+w y Δy+w L ΔL+w a Δa+w b Δb. Based on the printer's internal physical model and control logic, a mapping relationship between errors and control parameters is established. For example, horizontal displacement error is related to the pulse frequency of the printhead's horizontal stepper motor. When Δx is not zero, the pulse frequency is adjusted based on a pre-determined proportionality factor. Color deviation is related to the voltage regulation of the ink supply system. By adjusting the voltage, the ink ejection volume is changed to achieve color correction, accurately converting weighted errors into specific control parameter adjustments.

[0052] After the first round of comparison and calibration, return to step S2 with the adjusted control parameters and print the color calibration pattern again. Repeat the series of actions such as input and comparison to start a new round of calibration. In each round of iteration, closely monitor the error correction effect. If it is found that the color deviation has improved after the previous round of adjustment but still does not meet the standard, the next round will be adjusted. L 、w a 、w b Increase by 0.1, and at the same time decrease the displacement error weight by the same amount, and calculate the rate of change of the comprehensive weighted error before and after each round of iteration. The formula is: Among them E n is the comprehensive weighted error of the nth round, E n+1 This is the n+1th round. When the decrease in this value is less than the set 1% threshold for two consecutive rounds, it means that the calibration process is complete and the parameters can stably output high-quality color matching results.

[0053] A device for color calibration of channels within the same printhead includes at least one processor, at least one memory, and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, an acquisition method for color calibration of channels within the same printhead is implemented.

[0054] A storage medium stores computer program instructions, which, when executed by a processor, implement the above-mentioned method for color registration calibration of channels within the same printhead.

[0055] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for color calibration of channels within the same printhead, characterized in that: The steps include: S1, obtaining a color calibration pattern and importing it into a printer system; S2, according to step S1, printing a color calibration pattern; S3, inputting the color calibration pattern printed in step S2 into the image processing software; S4, importing the color calibration pattern of step S1 into the image processing software; S5, comparing the color calibration pattern entered in step S3 with the color calibration pattern imported in step S4 and calibrating the control parameters of the printer system according to the comparison result; In step S1, the color calibration pattern is specifically a plurality of patterns consisting of a plurality of large squares, small squares, and color squares in a grid format, wherein the color square is placed in the middle of the small squares, and the small squares are placed in the middle of the large squares, and adjustment parameters of the same size as those in the printer system are set below each group of patterns; The step S3 is specifically to scan the color calibration pattern printed in step S2 completely and enter it into the image processing software, and adjust the size of the entered color calibration pattern in the image processing software; The method of resizing the recorded color calibration pattern in the image processing software includes the following steps: L1, obtaining edge information of the recorded color calibration pattern; L2, obtaining edge parameters of the printing paper; L3, adjusting the edge parameters of the recorded color calibration pattern in the same proportion as the edge parameters of the printing paper; L4, repeating steps L1-L3 until the edge parameters of the recorded color calibration pattern are exactly the same as the edge parameters of the printing paper; In step S2, before printing, the print preview image is captured to determine the specific position of the color calibration pattern on the printing paper, specifically, the coordinate parameters of the four corners of the color calibration pattern are obtained with the middle of the printing paper as the center point; The operation steps of step S5 in the image processing software are as follows: Q1, adjusting the transparency of the color calibration pattern imported in step S4 to 50-70%; Q2, placing the color calibration pattern obtained in step Q1 at the print preview position in step S2; Q3, placing the color calibration pattern obtained in step S3 at the print preview position in step S2; Q4, identifying and comparing the two patterns in steps Q2 and Q3 using an image recognition method; Q5, outputting the comparison result; The comparison result of step Q5 is specifically to compare each group of patterns in the recorded color calibration pattern and the imported color calibration pattern, take the imported color calibration pattern as the standard, completely overlap the large square of the recorded color calibration pattern, hide the small square of the recorded color calibration pattern, extract the color square of the recorded color calibration pattern and place it in the small square of the imported color calibration pattern until the small square is completely filled with the color square, and use the difference between the coordinate parameters before and after the movement as the basis for adjusting the control parameters of the printer system.

2. A device for color calibration of channels within the same printhead, characterized in that: The system comprises at least one processor, at least one memory and computer program instructions stored in the memory, and when the computer program instructions are executed by the processor, the method according to claim 1 is implemented.

3. A storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method according to claim 1 is implemented.

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