Method for quickly adjusting printing chromatic aberration of ceramic ink jet printer

Abstract

The invention relates to the technical field of printing color difference rapid adjustment, and discloses a ceramic ink jet printer printing color difference rapid adjustment method, which comprises the following steps: carrying out image acquisition on a printing color and a standard color through an image acquisition device; the collected image data is preprocessed; performing color comparison on the color features extracted from the image data; a comparison result of color features in collected image data is evaluated, printing colors and standard colors are collected, the image recognition technology is used for comparing the single colors with the standard colors one by one, preliminary compensation parameters are obtained, then the printer is preliminarily adjusted and compensated, the adjusted colors are printed again, comparison is conducted, and the printing quality is improved. And the color matching process is full-automatic, and the efficiency and the accuracy are improved, so that the color difference between the pattern color printed on the surface of the ceramic and the standard color is reduced, the overall quality of the ceramic is further improved, and the aesthetic requirements of people on the ceramic and the patterns and the colors on the surface of the ceramic are met.

Description

Technical Field

[0001] The invention relates to the technical field of rapid adjustment of printing color difference, and in particular to a rapid adjustment method of printing color difference of a ceramic inkjet machine. Background Art

[0002] Ceramic inkjet printing technology is an advanced digital printing technology that uses the inkjet printing principle to spray ceramic ink directly onto the ceramic surface or body to form the desired pattern or texture. This technology combines the precision of inkjet printing with the particularity of ceramic materials, and can achieve high-precision and high-efficiency ceramic decoration and processing.

[0003] However, as people's aesthetic demands and quality requirements for ceramic products gradually increase, people begin to pay more attention to the patterns printed on the ceramic surface and the colors of the patterns; Ceramic inkjet printers need to have ink added to them before use. Since the colors of inks from different batches may vary and if the ink is not thoroughly shaken before adding ink, the pigment particles in the ink will be unevenly distributed, causing the actual pattern color printed on the porcelain surface by the ceramic inkjet printer to be inconsistent with the expected pattern color, resulting in color difference, which will reduce the quality of the printed products and fail to meet the aesthetic needs of consumers. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for quickly adjusting the color difference of printing of a ceramic inkjet printer to solve the shortcomings of the background technology.

[0005] In order to achieve the above object, according to one aspect of the present invention, a method for quickly adjusting the color difference of printing by a ceramic inkjet printer is provided, comprising the following steps: S1: Capturing images of the printing color and the standard color through an image acquisition device; S2: preprocessing the collected image data; S3: Perform color comparison on the color features extracted from the image data; S4: Evaluate the comparison results of the color features in the collected image data.

[0006] In a preferred embodiment, in S1, an image acquisition device is arranged in a dim environment, an LED light source is arranged in the environment, and image data of the product printed by the ceramic inkjet machine and the corresponding standard color card are respectively acquired through the image acquisition device.

[0007] In a preferred embodiment, after the image data is collected in S2, noise in the collected image data is removed based on a mean filter and normalization is performed.

[0008] In a preferred embodiment, the mean filter smoothes the image by calculating the average value of each pixel in the collected image data and the pixels in its neighborhood, using the formula: The pixel after filtering is calculated at point The pixel value at , where is the original image at point The pixel value at So The neighborhood set centered on is a 3x3 rectangular window. Is a collection The total number of pixels in .

[0009] In a preferred embodiment, the normalization processing of the image data is performed by linearly normalizing the values ​​of the denoised image data to , through the formula: The linearly normalized image data is calculated in Image values ​​within the range , where is the original data, is the minimum value in the data set, is the maximum value in the data set.

[0010] In a preferred embodiment, the S6 is normalized to The original color space of the image in the interval is converted into the value of the XYZ color space through the formula: in, is the conversion matrix. For the sRGB color space, the matrix is: M_{sRGB \to XYZ} = begin{bmatrix} 0.4124&0.3576&0.1805 \\ 0.2126&0.7152&0.0722 \\ 0.0193&0.1192&0.9505 end{bmatrix}.

[0011] In a preferred embodiment, in S6, based on the value of the XYZ color space, the image data in the original color space is numerically converted to the CIELAB color space, and then the L*, a*, and b* color components of the image data in the CIELAB color space are extracted, through the expression: in, , , , Indicates the XYZ value converted to the brightness value in the CIELAB color space. Indicates that the XYZ value is converted to the red and green axis values ​​in the CIELAB color space. Indicates that the XYZ value is converted to the yellow-blue axis value in the CIELAB color space.

[0012] 8. The method for quickly adjusting the color difference of ceramic inkjet printing according to claim 7, characterized in that in the CIELAB color space, , , The total color difference between the color printed by the ceramic inkjet printer and the standard color is calculated based on the three parameters of L*, a*, and b*, and the calculation formula of the total color difference is: in, , , They are the differences between the printed color and the standard color in the three directions of L*, a*, and b*.

[0013] In a preferred embodiment, the color difference result value between the color printed by the ceramic inkjet machine and the standard color is judged in S4, and the judging steps are as follows: S1: , the color difference between the ceramic inkjet printing color and the standard color is large, which is unqualified; S2: , the color difference between the printed color of the ceramic inkjet machine and the standard color is small and qualified.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. In the method for quickly adjusting the color difference of ceramic inkjet printing, the image data of the printed color and the standard color are collected by an image acquisition device, and the single color is compared with each standard color one by one by using image recognition technology. The image comparison information parameters of the above combination are analyzed in a simulation state to obtain preliminary compensation parameters, and then the printer is compensated after preliminary adjustment. The adjusted color is printed again, compared, adjusted for the second time, printed again, and image comparison is performed. The above steps are repeated many times to make the color difference approach zero. The color adjustment process is fully automatic, which improves efficiency and accuracy, thereby reducing the color difference between the pattern color printed on the ceramic surface and the standard color, thereby improving the overall quality of the ceramic and meeting people's aesthetic needs for ceramics and their surface patterns and colors.

[0015] 2. In the method for quickly adjusting the color difference of ceramic inkjet printing, when collecting printing color image data, the image acquisition device is placed in a Hunan environment and a stable light source is provided by an LED lamp, thereby avoiding changes in the brightness, color temperature, spectral distribution and other characteristics of the light source in the external environment that lead to color deviation, thereby improving the accuracy of the ceramic inkjet ink color adjustment compensation, reducing the color deviation between the adjusted and compensated printed color and the standard color, and improving the quality of ceramics produced by the ceramic inkjet machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flowchart of the overall process of the present invention. DETAILED DESCRIPTION

[0017] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0018] See also Figure 1 As shown, the purpose of this embodiment is to provide a method for quickly adjusting the color difference of printing by a ceramic inkjet printer, comprising the following steps: S1: Capturing images of the printing color and the standard color through an image acquisition device; S2: preprocessing the collected image data; S3: Perform color comparison on the color features extracted from the image data; S4: Evaluate the comparison results of the color features in the collected image data.

[0019] In S1, an image acquisition device is set in a dim environment, an LED light source is set in the environment, and image data of the product printed by the ceramic inkjet machine and the corresponding standard color card are respectively acquired through the image acquisition device. By setting the image acquisition device in a dim environment, the color deviation in the acquired image data caused by the change of the light source in the external environment is avoided. At the same time, the LED light is used to provide a stable light source for the dim environment, so that the image data acquired by the image acquisition device is more representative, thereby improving the effectiveness of the subsequent color difference results.

[0020] After the image data is collected in S2, the noise in the collected image data is removed based on the mean filter and normalized. The noise in the image data usually manifests as sudden changes or sharp edges in the image. The image is smoothed by calculating the average value of each pixel in the image and the surrounding pixels through the mean filter, which helps to reduce random noise in the image, avoid noise interference with the image, and improve the quality of the collected image data. The pixel values ​​of the image data are mapped to a uniform range through normalization, thereby eliminating the pixel value differences between different images caused by differences in light intensity and data acquisition device parameters, thereby improving data consistency.

[0021] The mean filter smoothes the image by calculating the average value of each pixel in the collected image data and the pixels in its neighborhood, using the formula: The pixel after filtering is calculated at point The pixel value at , where is the original image at point The pixel value at So The neighborhood set centered on is a 3x3 rectangular window. Is a collection The total number of pixels in the image. The image is often disturbed by noise during the acquisition and transmission process, resulting in small, irregular brightness changes in the image. The image is smoothed by calculating the average value of each pixel and its neighborhood pixels, thereby suppressing the impact of noise on the image and improving image quality.

[0022] Normalization of image data is done by linearly normalizing the values ​​of the denoised image data to , through the formula: The linearly normalized image data is calculated in Image values ​​within the range , where is the original data, is the minimum value in the data set, It is the maximum value in the data set. Different images or different parts of the same image have different pixel value distribution ranges due to different conditions such as lighting and shooting equipment. The pixel values ​​of the image data are unified into the interval [0,1] through normalization processing, so that the data between different images can be compared and analyzed on the same scale, which helps to find the similarities and differences between images, improve the stability and robustness of the algorithm, improve the accuracy, facilitate data comparison and analysis, and enhance the image visualization effect.

[0023] S6 will be normalized to The original color space of the image in the interval is converted into the value of the XYZ color space through the formula: in, is the conversion matrix. For the sRGB color space, the matrix is: M_{sRGB \to XYZ}= begin{bmatrix} 0.4124&0.3576&0.1805 \\ 0.2126&0.7152&0.0722 \\ 0.0193&0.1192&0.9505 end{bmatrix}. The XYZ color space is a standardized color space based on the human eye's perception of color. It can simulate the human eye's response to color. Converting an image from the device-dependent sRGB color space to the XYZ color space can make the color representation of the image closer to the real color perceived by the human eye, thereby maintaining color consistency under different devices and display conditions.

[0024] In S6, based on the value of the XYZ color space, the image data in the original color space is numerically converted to the CIELAB color space, and then the L*, a*, and b* color components of the image data in the CIELAB color space are extracted, through the expression: in, , , , Indicates the XYZ value converted to the brightness value in the CIELAB color space. Indicates that the XYZ value is converted to the red and green axis values ​​in the CIELAB color space. Indicates that the XYZ value is converted to the yellow-blue axis value in the CIELAB color space; Convert image data from XYZ color space to CIELAB color space and extract L 、a , b* color component, which is used to improve the consistency of color perception, quantify and compare color differences, support a wider range of image processing algorithms, improve the accuracy of color processing, facilitate color management and color reproduction, and support the flexibility of color space conversion.

[0025] In the CIELAB color space, , , The total color difference between the color printed by the ceramic inkjet printer and the standard color is calculated based on the three parameters of L*, a*, and b*, and the calculation formula of the total color difference is: in, , , They are the differences between the printed color and the standard color in the three directions of L*, a*, and b*. The three parameters of L*, a*, and b* are used to calculate the total color difference between the printed color of the ceramic inkjet machine and the standard color, thereby quantifying the color difference, supporting color matching and correction, improving production efficiency, supporting color management, enhancing customer satisfaction, and meeting people's needs for ceramic aesthetics.

[0026] In S4, the color difference result value between the color printed by the ceramic inkjet machine and the standard color is judged, and the judging steps are as follows: S1: , the color difference between the ceramic inkjet printing color and the standard color is large, which is unqualified; S2: The color difference between the printed color and the standard color of the ceramic inkjet machine is small and qualified. When the calculated color difference value between the printed color and the standard color of the control is greater than or equal to one, it means that the color difference between the printed color and the standard color of the control is large. At this time, the color difference result is fed back to the automatic adjustment terminal, so that the ceramic inkjet machine automatically adjusts and compensates the ink color, and then prints again, and then collects the new printed color of the image, and calculates the color difference again, and repeats this process until the color difference value between the printed color and the standard color is controlled within the range of less than one and greater than or equal to zero. At this time, the printed color will be close to the standard color, so that the patterns and colors printed on the ceramics meet people's aesthetic needs.

[0027] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. 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 quickly adjusting the color difference of ceramic inkjet printing, characterized in that: The steps include: S1: Capturing images of the printing color and the standard color through an image acquisition device; S2: preprocessing the collected image data; S3: Perform color comparison on the color features extracted from the image data; S4: Evaluate the comparison results of the color features in the collected image data.

2. The method for quickly adjusting the color difference of ceramic inkjet printing according to claim 1, characterized in that: In S1, an image acquisition device is arranged in a dim environment, an LED light source is arranged in the environment, and image data of the product printed by the ceramic inkjet machine and the corresponding standard color card are respectively acquired through the image acquisition device.

3. The method for quickly adjusting the color difference of ceramic inkjet printing according to claim 1, characterized in that: In S2, after the image data is collected, noise in the collected image data is removed based on a mean filter and normalization is performed.

4. The method for quickly adjusting the color difference of ceramic inkjet printing according to claim 3, characterized in that: The mean filter smoothes the image by calculating the average value of each pixel in the collected image data and the pixels in its neighborhood, through the formula: The pixel after filtering is calculated at point The pixel value at , where is the original image at point The pixel value at So The neighborhood set centered on is a 3x3 rectangular window. Is a collection The total number of pixels in .

5. The method for quickly adjusting the color difference of ceramic inkjet printing according to claim 3, characterized in that: The normalization processing of the image data is performed by linearly normalizing the value of the denoised image data to , through the formula: The linearly normalized image data is calculated in Image values ​​within the range , where is the original data, is the minimum value in the data set, is the maximum value in the data set.

6. The method for quickly adjusting color difference of ceramic inkjet printing according to claim 5, characterized in that: The S6 will be normalized to The original color space of the image in the interval is converted into the value of the XYZ color space through the formula: in, is the conversion matrix. For the sRGB color space, the matrix is: M_{sRGB \to XYZ} =begin{bmatrix} 0.4124 & 0.3576 & 0.1805 \\ 0.2126 & 0.7152 & 0.0722 \\ 0.0193& 0.1192 & 0.9505 end{bmatrix}.

7. The method for quickly adjusting the color difference of ceramic inkjet printing according to claim 6, characterized in that: In S6, based on the value of the XYZ color space, the image data in the original color space is numerically converted to the CIELAB color space, and then the L*, a*, and b* color components of the image data in the CIELAB color space are extracted, through the expression: in, , , , Indicates the XYZ value converted to the brightness value in the CIELAB color space. Indicates that the XYZ value is converted to the red and green axis values ​​in the CIELAB color space. Indicates that the XYZ value is converted to the yellow-blue axis value in the CIELAB color space.

8. The method for quickly adjusting the color difference of ceramic inkjet printing according to claim 7, characterized in that: In the CIELAB color space, , , The total color difference between the color printed by the ceramic inkjet printer and the standard color is calculated based on the three parameters of L*, a*, and b*, and the calculation formula of the total color difference is: in, , , They are the differences between the printed color and the standard color in the three directions of L*, a*, and b*.

9. The method for quickly adjusting color difference of ceramic inkjet printing according to claim 1, characterized in that: In S4, the color difference result value between the color printed by the ceramic inkjet machine and the standard color is judged, and the judging steps are as follows: S1: , the color difference between the ceramic inkjet printing color and the standard color is large, which is unqualified; S2: , the color difference between the printed color of the ceramic inkjet machine and the standard color is small and qualified.

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