A method and device for calibrating screen color gamut

Abstract

The present invention provides a method and device for calibrating a screen color gamut. The method first substitutes the target CIE color coordinates into a screen color feature fitting equation to calculate a pre-calibrated grayscale; then substitutes the pre-calibrated grayscale into the screen feature parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; then calculates the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates, and when the color difference is not greater than a preset tolerance value, confirms that the pre-calibrated grayscale has been correctly calibrated, and outputs the pre-calibrated grayscale as a calibration result. During the calibration process, after measuring the screen feature parameters and the screen color feature fitting equation, the screen feature parameters and the screen color feature fitting equation are saved, different target CIE color coordinates are set as specifications for different color gamuts, and the specifications for different color gamuts are calibrated, so that the same screen to be calibrated can adapt to different color gamut calibration results, with strong flexibility, so that the screen color accuracy can be calibrated quickly and flexibly.

Description

Technical Field

[0001] The present invention relates to the technical field of color gamut processing, and in particular to a method and device for calibrating a screen color gamut. Background Art

[0002] Mobile device screens are gradually being promoted to wide color gamut screens, and manufacturers and users are paying more and more attention to the color accuracy of screens in different color gamuts, especially the widely used sRGB color gamut and the wide color gamut standard DCI-P3 color gamut. However, due to cost factors, it is difficult for mobile phone LCD and OLED screens to achieve the same color accuracy on each screen (the greater the color difference, the lower the color accuracy; the smaller the color difference, the higher the color accuracy). Therefore, each screen needs to be calibrated for different color gamuts before leaving the factory. The existing calibration method requires the colorimetry and calculation of each screen in each color gamut, which takes a long time and is difficult to meet the requirements of mass production. Summary of the invention

[0003] The present invention provides a screen color gamut calibration method and device, which can quickly and flexibly calibrate the screen color accuracy.

[0004] In a first aspect, the present invention provides a method for calibrating a screen color gamut, the method comprising:

[0005] Measuring screen characteristic parameters of the screen to be calibrated, the screen characteristic parameters including a number of grayscales and the CIE color coordinates corresponding to each grayscale;

[0006] According to the screen characteristic parameters, a screen color characteristic fitting equation is established;

[0007] Set the target CIE color coordinates for the screen to be calibrated;

[0008] Substitute the target CIE color coordinates into the screen color characteristic fitting equation to calculate the pre-calibrated grayscale;

[0009] Substituting the pre-calibrated grayscale into the screen characteristic parameters, estimating the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale;

[0010] Calculating the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates;

[0011] When the color difference is not greater than the preset tolerance value, it is confirmed that the pre-calibrated grayscale has been correctly calibrated, and the pre-calibrated grayscale is output as a calibration result.

[0012] In the above scheme, the target CIE color coordinates are first substituted into the screen color feature fitting equation to calculate the pre-calibrated grayscale; then the pre-calibrated grayscale is substituted into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; then the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is calculated, and when the color difference is not greater than the preset tolerance value, it is confirmed that the pre-calibrated grayscale has been correctly calibrated, and the pre-calibrated grayscale is output as the calibration result. During the calibration process, after measuring the screen characteristic parameters and the screen color feature fitting equation, the screen characteristic parameters and the screen color feature fitting equation can be saved, and then different target CIE color coordinates can be set as specifications for different color gamuts, and the specifications for different color gamuts can be calibrated, so that after one measurement, the screen to be calibrated can be calculated and calibrated for multiple color gamuts without the need to measure the screen data again. Compared with the prior art of measuring and calculating the chromaticity of each screen in each color gamut, the number of measurements is reduced, so that the same screen to be calibrated can adapt to different color gamut calibration results, and it can also be performed offline with strong flexibility, so that the screen color can be calibrated quickly and flexibly.

[0013] In a specific implementation, when the color difference is greater than the tolerance value, it is determined that the pre-calibrated grayscale is unqualified, so as to quickly confirm whether the screen to be calibrated is qualified in each color gamut.

[0014] In a specific embodiment, when the color difference is greater than the tolerance value, the calibration method further includes:

[0015] Step 21: Taking the pre-calibrated grayscale as the center, select several neighboring grayscales around the center;

[0016] Step 22: Substitute each neighborhood grayscale into the screen characteristic parameters to calculate the neighborhood CIE color coordinates corresponding to each neighborhood grayscale;

[0017] Step 23: Calculate the color difference between each neighborhood CIE color coordinate and the target CIE color coordinate, and find the minimum color difference therebetween;

[0018] Step 24: When the minimum color difference is not greater than the tolerance value, confirm that the neighborhood grayscale corresponding to the minimum color difference has been correctly calibrated, and output the neighborhood grayscale corresponding to the minimum color difference as the calibration result. When the color difference is greater than the tolerance value, by adding a post-processing link, the pre-calibration data that does not meet the conditions is corrected, and the results are corrected using the existing grayscale-chromaticity data, without the need to measure the screen data additionally, which effectively improves the accuracy of the calibration results and can also quickly and flexibly calibrate the screen color accuracy.

[0019] In a specific embodiment, when the minimum color difference is greater than the tolerance value, the calibration method further includes:

[0020] Step 25: Take the neighborhood grayscale corresponding to the minimum color difference as the new center, and repeat steps 21 to 25 until the calculated minimum color difference is not greater than the tolerance value, and output the neighborhood grayscale corresponding to the minimum color difference as the calibration result. The accuracy of the calibration result is further increased by optimizing the results through multiple cycles of iterations.

[0021] In a specific implementation, measuring the screen characteristic parameters of the screen to be calibrated specifically includes: using a colorimeter to measure the screen characteristic parameters of the screen to be calibrated, so as to quickly collect the screen characteristic parameters of the screen to be calibrated.

[0022] In a specific implementation, establishing a screen color feature fitting equation according to the screen feature parameters includes:

[0023] The following characteristic equation is established:

[0024]

[0025] Among them, X, Y, Z represent CIE color coordinate parameters, R, G, B represent grayscale parameters, and a r～t ~j r～t represents the fitting parameters;

[0026] Substitute several grayscales and the CIE color coordinates corresponding to each grayscale into the characteristic equation to calculate a r～t ~j r～t , and obtain the screen color feature fitting equation. Improve the accuracy of the screen color feature fitting equation, while reducing the amount of calculation and shortening the calibration time.

[0027] In a specific embodiment, substituting the precalibrated grayscale into the screen characteristic parameters and estimating the precalibrated CIE color coordinates corresponding to the precalibrated grayscale includes: substituting the precalibrated grayscale into the screen characteristic parameters, and using a tetrahedral interpolation method, a triangular prism method, or a trilinear method to estimate the precalibrated CIE color coordinates corresponding to the precalibrated grayscale, so as to facilitate fast and accurate estimation of the precalibrated CIE color coordinates corresponding to the precalibrated grayscale based on the screen characteristic parameters.

[0028] In a specific embodiment, calculating the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates includes: calculating the Delta-E and / or the JNCD between the target CIE color coordinates and the pre-calibrated CIE color coordinates, so as to comprehensively reflect the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates.

[0029] In a specific embodiment, selecting several neighborhood grayscales around the center includes: selecting several grayscales around the center in six directions of (1, 0, 0), (0, 1, 0), (0, 0, 1), (-1, 0, 0), (0, -1, 0), and (0, 0, -1) as several neighborhood grayscales to improve the accuracy of calibration.

[0030] In a second aspect, the present invention also provides a calibration device for a screen color gamut, the calibration device comprising: a screen characteristic parameter measurement module, a characteristic equation fitting module, a target CIE color coordinate setting module, a pre-calibrated grayscale calculation module, a pre-calibrated CIE color coordinate calculation module, a color difference calculation module and a calibration result output module. Among them, the screen characteristic parameter measurement module is used to measure the screen characteristic parameters of the screen to be calibrated, and the screen characteristic parameters include a plurality of grayscales and the CIE color coordinates corresponding to each grayscale. The characteristic equation fitting module is used to establish a screen color characteristic fitting equation according to the screen characteristic parameters. The target CIE color coordinate setting module is used to set the target CIE color coordinates for the screen to be calibrated. The pre-calibrated grayscale calculation module is used to substitute the target CIE color coordinates into the screen color characteristic fitting equation to calculate the pre-calibrated grayscale. The pre-calibrated CIE color coordinate calculation module is used to substitute the pre-calibrated grayscale into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale. The color difference calculation module is used to calculate the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates. The calibration result output module is used to confirm that the pre-calibrated grayscale has been correctly calibrated when the color difference is not greater than a preset tolerance value, and output the pre-calibrated grayscale as a calibration result.

[0031] In the above scheme, the target CIE color coordinates are first substituted into the screen color feature fitting equation to calculate the pre-calibrated grayscale; then the pre-calibrated grayscale is substituted into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; then the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is calculated, and when the color difference is not greater than the preset tolerance value, it is confirmed that the pre-calibrated grayscale has been correctly calibrated, and the pre-calibrated grayscale is output as the calibration result. During the calibration process, after measuring the screen characteristic parameters and the screen color feature fitting equation, the screen characteristic parameters and the screen color feature fitting equation can be saved, and then different target CIE color coordinates can be set as specifications for different color gamuts, and the specifications for different color gamuts can be calibrated, so that after one measurement, the screen to be calibrated can be calculated and calibrated for multiple color gamuts without the need to measure the screen data again. Compared with the prior art of measuring and calculating the chromaticity of each screen in each color gamut, the number of measurements is reduced, so that the same screen to be calibrated can adapt to different color gamut calibration results, and it can also be performed offline with strong flexibility, so that the screen color can be calibrated quickly and flexibly. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flowchart of a screen color gamut calibration method provided by an embodiment of the present invention;

[0033] Figure 2 A flowchart of another screen color gamut calibration method provided by an embodiment of the present invention;

[0034] Figure 3 A flowchart of another screen color gamut calibration method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In order to facilitate the understanding of the screen color gamut calibration method provided by the embodiment of the present invention, the application scenario of the calibration method provided by the embodiment of the present invention is first explained below. The calibration method is applied to the color gamut calibration process of the screen, and can be specifically applied to image processing chips related to image post-processing and image display. The color gamut calibration (ColorCalibration) refers to the use of technical means to make the color performance of the display device close to the standard color under a certain color gamut standard. For example, under the sRGB color gamut, through color gamut calibration, the Delta-E of the red grayscale (255, 0, 0) and the sRGB standard red CIE XYZ (0.42146, 0.21267, 0.01922) is less than 2.0, and there is almost no difference in perception between the two. The screen color gamut calibration method is described in detail below in conjunction with the accompanying drawings.

[0037] refer to Figure 1 The screen color gamut calibration method provided by the embodiment of the present invention includes:

[0038] Step 10: Measure the screen characteristic parameters of the screen to be calibrated, which include several grayscales and the CIE color coordinates corresponding to each grayscale;

[0039] Step 20: Establish a screen color feature fitting equation based on the screen feature parameters;

[0040] Step 30: Set the target CIE color coordinates for the screen to be calibrated;

[0041] Step 40: Substitute the target CIE color coordinates into the screen color feature fitting equation to calculate the pre-calibrated grayscale;

[0042] Step 50: Substitute the pre-calibrated grayscale into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale;

[0043] Step 60: Calculate the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates;

[0044] Step 70: When the color difference is not greater than a preset tolerance value, confirm that the pre-calibrated grayscale has been correctly calibrated, and output the pre-calibrated grayscale as a calibration result.

[0045] In the above scheme, the target CIE color coordinates are first substituted into the screen color feature fitting equation to calculate the pre-calibrated grayscale; then the pre-calibrated grayscale is substituted into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; then the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is calculated, and when the color difference is not greater than the preset tolerance value, it is confirmed that the pre-calibrated grayscale has been correctly calibrated, and the pre-calibrated grayscale is output as the calibration result. During the calibration process, after measuring the screen characteristic parameters and the screen color feature fitting equation, the screen characteristic parameters and the screen color feature fitting equation can be saved, and then different target CIE color coordinates can be set as specifications for different color gamuts, and the specifications for different color gamuts can be calibrated, so that after one measurement, the screen to be calibrated can be calculated and calibrated for multiple color gamuts without the need to measure the screen data again. Compared with the prior art that measures and calculates the chromaticity of each screen in each color gamut, the number of measurements is reduced, so that the same screen to be calibrated can be adapted to different color gamut calibration results, and it can also be performed offline, which has strong flexibility, so that the screen color can be calibrated quickly and flexibly. The above steps are described in detail below with reference to the accompanying drawings.

[0046] First, refer to Figure 1 , Figure 2 and Figure 3 , measure the screen characteristic parameters of the screen to be calibrated, the screen characteristic parameters include several grayscales, and the CIE color coordinates corresponding to each grayscale. For example, the grayscale can be a red grayscale (255, 0, 0), and the corresponding CIE color coordinates are measured. The number of grayscales can be 5, 10, 20, etc., and correspondingly, the CIE color coordinates corresponding to each grayscale need to be measured. During the specific measurement, a colorimeter can be used to measure the screen characteristic parameters of the screen to be calibrated, so as to facilitate the rapid acquisition of the screen characteristic parameters of the screen to be calibrated. Afterwards, the measured screen characteristic parameters can be stored and used as the screen color grayscale-color coordinate characteristic parameters in subsequent steps.

[0047] It should be explained that the CIE color coordinates may be color coordinates in the CIE 1931 Color space. In the study of color perception, the CIE 1931 XYZ color space (also called the CIE 1931 color space) is one of the first color spaces to be defined mathematically. It was created by the International Commission on Illumination (CIE) in 1931. The CIE XYZ color space was derived from a series of experiments conducted by W. David Wright (Wright 1928) and John Guild (Guild 1931) in the late 1920s.

[0048] Next, if Figure 1 As shown, according to the screen characteristic parameters, a screen color characteristic fitting equation is established, and the corresponding relationship between the grayscale of the screen to be calibrated and the corresponding CIE color coordinates is reflected by the screen color characteristic fitting equation. When the screen color characteristic fitting equation is specifically established, a mathematical method can be used, for example, in the following manner:

[0049] First establish the following characteristic equation:

[0050]

[0051] Among them, X, Y, Z represent CIE color coordinate parameters, R, G, B represent grayscale parameters, and a r～t ~j r～t represents the fitting parameters;

[0052] Then, the grayscales measured in the previous steps and the CIE color coordinates corresponding to each grayscale are substituted into the characteristic equation to calculate a r～t ~j r～t , and obtain the screen color feature fitting equation. That is, through a quadratic polynomial, the inverse mapping equation from the CIE color coordinates of the screen to be calibrated to the grayscale of the screen to be calibrated is fitted, so that any CIE color coordinate can be converted to its corresponding grayscale value. The above fitting method can improve the accuracy of the screen color feature fitting equation, while reducing the amount of calculation and shortening the calibration time.

[0053] It should be noted that the characteristic equation established is not limited to the quadratic polynomial model shown above, and other characteristic equation models may also be used, for example, a linear polynomial model, a cubic polynomial model, etc.

[0054] Next, refer to Figure 1 , Figure 2 and Figure 3 , set the target CIE color coordinates for the screen to be calibrated, that is, set the target color gamut. The target color gamut is usually fixed, and each target CIE color coordinate in the color gamut is CIEXYZtarget The corresponding target grayscale RGB target Specifically, several different target CIE color coordinates can be set at one time as specifications for different color gamuts, and then the specifications for different color gamuts can be calibrated separately without measuring.

[0055] It should be explained that a color gamut is a complete subset of colors defined using a three-dimensional body, usually described by a bounded solid in a uniform color space. The red, green, and blue RGB color space is a standard color space definition that is widely used in the computer industry. At present, the color space in the computer industry all follows the definition of the RGB color space, such as images created in the sRGB color space and high dynamic range videos using the BT.2020 color space.

[0056] Next, refer to Figure 1 and Figure 2 , the target CIE color coordinates CIEXYZ target Substitute into the screen color characteristic fitting equation to calculate the pre-calibrated grayscale RGB pre_correct When a plurality of target CIE color coordinates are set, the pre-calibrated gray scale corresponding to each target CIE color coordinate may be calculated respectively in the manner shown above.

[0057] Next, if Figure 1 and Figure 2 As shown, the pre-calibrated grayscale RGB pre_correct Substitute into the screen characteristic parameters, and estimate the pre-calibrated CIE color coordinates CIEXYZ corresponding to the pre-calibrated grayscale according to the screen color grayscale-color coordinate characteristic parameters pre_correct When multiple target CIE color coordinates are set and multiple pre-calibrated grayscales are calculated, each pre-calibrated grayscale can be substituted into the screen characteristic parameters respectively, and the pre-calibrated CIE color coordinates corresponding to each pre-calibrated grayscale can be estimated based on the distribution relationship between each grayscale and the corresponding CIE color coordinates in the measured screen characteristic parameters.

[0058] When substituting the pre-calibrated grayscale into the screen characteristic parameters and estimating the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale, the pre-calibrated grayscale can be substituted into the screen characteristic parameters, and the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale can be estimated by using tetrahedral interpolation method, triangular prism method or trilinear method, so as to quickly and accurately estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale according to the screen characteristic parameters. It should be understood that in addition to the above-mentioned method, other estimation methods can also be used.

[0059] Next, if Figure 1 , Figure 2 and Figure 3As shown, calculate the target CIE color coordinates CIEXYZ target and pre-calibrated CIE color coordinates CIEXYZ pre_correct The color difference between the pre-calibrated CIE color coordinates and the target color coordinates can be understood to understand the color difference between the pre-calibrated CIE color coordinates and the target color coordinates, thereby understanding the color accuracy between the pre-calibrated CIE color coordinates and the target color coordinates. If the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is larger, it means that the color accuracy between the target CIE color coordinates and the pre-calibrated CIE color coordinates is lower; if the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is smaller, it means that the color accuracy between the target CIE color coordinates and the pre-calibrated CIE color coordinates is higher.

[0060] When calculating the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates, the Delta-E or / and the just-discrimination difference JNCD between the target CIE color coordinates and the pre-calibrated CIE color coordinates can be calculated, so as to comprehensively reflect the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates. Specifically, only the Delta-E between the target CIE color coordinates and the pre-calibrated CIE color coordinates can be calculated, and the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates can be reflected by Delta-E. It is also possible to only calculate the just-discrimination difference JNCD between the target CIE color coordinates and the pre-calibrated CIE color coordinates, and reflect the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates by the just-discrimination difference JNCD. Of course, it is also possible to simultaneously calculate the Delta-E and the just-discrimination difference JNCD between the target CIE color coordinates and the pre-calibrated CIE color coordinates, and reflect the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates by the two indicators of Delta-E and just-discrimination difference JNCD. It should also be noted that the indicator reflecting the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is not limited to Delta-E and JNCD. In addition, other methods can also be used.

[0061] It should be explained that color difference or color accuracy is the difference between the color performance of a color device in a specified color gamut and the standard color. Generally, the smaller the difference, the more accurate the color performance. The industry usually uses CIE2000Delta-E and JNCD to measure the size of color difference.

[0062] Next, refer to Figure 1 and Figure 3 When the color difference is not greater than the preset tolerance value, it means that the pre-calibration result meets expectations, then the pre-calibration grayscale is confirmed to have been correctly calibrated, and the pre-calibration grayscale is output as the calibration result, that is, the calibrated pre-calibration grayscale value is output as the final calibration result RGB final_correct =RGB pre_correct, get the target grayscale RGB corresponding to different target CIE color coordinates target The tolerance value refers to the color deviation that can be tolerated in the calibration result, and the user can set it according to their own needs. Figure 3 , the size between the calculated color difference and the preset tolerance value can be compared to determine whether the calculated color difference is not greater than the preset tolerance value. If the judgment result is that the calculated color difference is not greater than the preset tolerance value, specifically, the color difference is less than or equal to the preset tolerance value, then it is confirmed that the pre-calibrated grayscale has been correctly calibrated, and the pre-calibrated grayscale is output as the calibration result. Of course, if the judgment result is that the calculated color difference is greater than the preset tolerance value, it means that the pre-calibrated result does not meet expectations, and the pre-calibrated grayscale is confirmed to be unqualified, which is convenient for quickly confirming whether the screen to be calibrated is qualified in each color gamut. It should be explained that in the aforementioned steps, if the Delta-E between the target CIE color coordinates and the pre-calibrated CIE color coordinates is calculated as the color difference, the preset tolerance value needs to be the tolerance value under the Delta-E indicator; if the JNCD between the target CIE color coordinates and the pre-calibrated CIE color coordinates is calculated as the color difference, the preset tolerance value needs to be the tolerance value under the JNCD indicator; and then they are compared respectively.

[0063] In addition, refer to Figure 2 and Figure 3 When the color difference calculated in Step 60 is greater than the preset tolerance value, the calibration method may further include a subsequent post-processing step. Figure 2 and Figure 3 , the calibration method may further include:

[0064] Step 21: Pre-calibrated Grayscale RGB pre_correct As the center, select several grayscale RGB neighborhoods around the center neighbor . Specifically select several grayscale RGB neighborhoods around the center neighbor When the center is (1, 0, 0), (0, 1, 0), (0, 0, 1), (-1, 0, 0), (0, -1, 0), (0, 0, -1) in the six directions, several grayscales around can be selected as several neighborhood grayscale RGB neighbor , improving the accuracy of calibration. Of course, several grayscales around the center in other directions can also be selected as several neighborhood grayscales.

[0065] Step 22: Substitute each neighborhood grayscale into the screen characteristic parameters and calculate the neighborhood CIE color coordinates CIEXYZ corresponding to each neighborhood grayscale neighbor ; If the selected neighborhood grayscale RGB neighbor When the number of is 6, 6 neighborhood grayscale RGB can be calculated neighborThe corresponding neighborhood CIE color coordinates CIEXYZ neighbor .

[0066] Step 23: Calculate the color difference between each neighborhood CIE color coordinate and the target CIE color coordinate, and find the minimum color difference therebetween;

[0067] Step 24: When the minimum color difference is not greater than the tolerance value, confirm that the neighborhood grayscale corresponding to the minimum color difference has been correctly calibrated, and output the neighborhood grayscale corresponding to the minimum color difference as the calibration result. Specifically, after finding the minimum color difference in step 23, compare the minimum color difference with the preset tolerance value to determine whether the minimum color difference is greater than the preset tolerance value. If the minimum color difference is not greater than the preset tolerance value, confirm that the neighborhood grayscale corresponding to the minimum color difference has been correctly calibrated, and output the neighborhood grayscale corresponding to the minimum color difference as the calibration result, that is, output the neighborhood grayscale corresponding to the minimum color difference as the final calibration result RGB final_correct =RGB neighbor_min , get the target grayscale RGB corresponding to different target CIE color coordinates target .

[0068] When the color difference is greater than the tolerance value, the pre-calibration data that does not meet the conditions is corrected by adding a post-processing step, and the results are corrected using the existing grayscale-chromaticity data. There is no need to measure the screen data additionally, which effectively improves the accuracy of the calibration results. At the same time, the screen color accuracy can also be calibrated quickly and flexibly.

[0069] Furthermore, reference Figure 2 and Figure 3 When the judgment result is that the minimum color difference found in step 23 is greater than the preset tolerance value, the calibration method may further include the following steps:

[0070] Step 25: Convert the grayscale RGB of the neighborhood corresponding to the minimum color difference neighbor_min As the new center, loop through steps 21 to 25 and continue to select several grayscale RGB neighborhoods around the center. neighbor Search calculations are performed until the calculated minimum color difference is no greater than the tolerance value, confirming that the neighborhood grayscale corresponding to the minimum color difference has been correctly calibrated, and the neighborhood grayscale corresponding to the minimum color difference is output as the calibration result to obtain the target grayscale RGB corresponding to different target CIE color coordinates. target By using the screen characteristic parameters to correct the calibration results, the results are optimized through multiple iterations until the expected color accuracy is achieved, further increasing the accuracy of the calibration results.

[0071] In the various embodiments shown above, the pre-calibrated grayscale is calculated by first substituting the target CIE color coordinates into the screen color feature fitting equation; then the pre-calibrated grayscale is substituted into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; then the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is calculated, and when the color difference is not greater than the preset tolerance value, it is confirmed that the pre-calibrated grayscale has been correctly calibrated, and the pre-calibrated grayscale is output as the calibration result. During the calibration process, after measuring the screen characteristic parameters and the screen color feature fitting equation, the screen characteristic parameters and the screen color feature fitting equation can be saved, and then different target CIE color coordinates are set as specifications for different color gamuts, and the specifications for different color gamuts are calibrated, so that after one measurement, the screen to be calibrated can be calibrated for multiple color gamuts without the need to measure the screen data again. Compared with the prior art of measuring and calculating the chromaticity of each screen in each color gamut, the number of measurements is reduced, so that the same screen to be calibrated can adapt to different color gamut calibration results, and it can also be performed offline with strong flexibility, so that the screen color can be calibrated quickly and flexibly.

[0072] In addition, an embodiment of the present invention further provides a calibration device for screen color gamut, the calibration device comprising: a screen characteristic parameter measurement module, a characteristic equation fitting module, a target CIE color coordinate setting module, a pre-calibration grayscale calculation module, a pre-calibration CIE color coordinate calculation module, a color difference calculation module and a calibration result output module. Among them, the screen characteristic parameter measurement module is used to measure the screen characteristic parameters of the screen to be calibrated, and the screen characteristic parameters include a plurality of grayscales and the CIE color coordinates corresponding to each grayscale. The characteristic equation fitting module is used to establish a screen color characteristic fitting equation according to the screen characteristic parameters. The target CIE color coordinate setting module is used to set the target CIE color coordinates for the screen to be calibrated. The pre-calibration grayscale calculation module is used to substitute the target CIE color coordinates into the screen color characteristic fitting equation to calculate the pre-calibration grayscale. The pre-calibration CIE color coordinate calculation module is used to substitute the pre-calibration grayscale into the screen characteristic parameters to estimate the pre-calibration CIE color coordinates corresponding to the pre-calibration grayscale. The color difference calculation module is used to calculate the color difference between the target CIE color coordinates and the pre-calibration CIE color coordinates. The calibration result output module is used to confirm that the pre-calibrated grayscale has been correctly calibrated when the color difference is not greater than a preset tolerance value, and output the pre-calibrated grayscale as a calibration result.

[0073] In the above scheme, the target CIE color coordinates are first substituted into the screen color feature fitting equation to calculate the pre-calibrated grayscale; then the pre-calibrated grayscale is substituted into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; then the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates is calculated, and when the color difference is not greater than the preset tolerance value, it is confirmed that the pre-calibrated grayscale has been correctly calibrated, and the pre-calibrated grayscale is output as the calibration result. During the calibration process, after measuring the screen characteristic parameters and the screen color feature fitting equation, the screen characteristic parameters and the screen color feature fitting equation can be saved, and then different target CIE color coordinates can be set as specifications for different color gamuts, and the specifications for different color gamuts can be calibrated, so that after one measurement, the screen to be calibrated can be calculated and calibrated for multiple color gamuts without the need to measure the screen data again. Compared with the prior art of measuring and calculating the chromaticity of each screen in each color gamut, the number of measurements is reduced, so that the same screen to be calibrated can adapt to different color gamut calibration results, and it can also be performed offline with strong flexibility, so that the screen color can be calibrated quickly and flexibly.

[0074] When applied, the screen color gamut calibration device can be applied to image processing chips related to image post-processing and image display, and the image processing chip can specifically be in the fields of image processing platform and display device. In addition, it should be noted that when the above-mentioned functional modules are specifically calculated, they can be implemented using the detailed steps shown in the above-mentioned screen color gamut calibration method section. It should be additionally noted that in addition to the above-mentioned functional modules, the above-mentioned screen color gamut calibration device can also include other functional modules, and also implement the calibration method additionally shown in the above-mentioned screen color gamut calibration method section. As a way of naming different functional modules, they can be determined accordingly according to the additional steps shown in the above-mentioned screen color gamut calibration method.

[0075] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for calibrating a screen color gamut, characterized in that: include: Measuring screen characteristic parameters of the screen to be calibrated, wherein the screen characteristic parameters include a plurality of grayscales and CIE color coordinates corresponding to each grayscale; According to the screen characteristic parameters, a screen color characteristic fitting equation is established, specifically: a characteristic equation is established, the measured grayscale and the CIE color coordinates corresponding to each grayscale are substituted into the characteristic equation, the fitting parameters are calculated, and the screen color characteristic fitting equation is obtained; Setting target CIE color coordinates for the screen to be calibrated; Substituting the target CIE color coordinates into the screen color characteristic fitting equation to calculate the pre-calibrated grayscale; Substituting the pre-calibrated grayscale into the screen characteristic parameters, and estimating the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; Calculating the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates; When the color difference is not greater than a preset tolerance value, confirming that the pre-calibrated grayscale has been correctly calibrated, and outputting the pre-calibrated grayscale as a calibration result; When the color difference is greater than the tolerance value, it is determined that the pre-calibrated grayscale is unqualified.

2. The calibration method according to claim 1, characterized in that: When the color difference is greater than the tolerance value, the calibration method further includes: Step 21: Taking the pre-calibrated grayscale as the center, select a number of neighborhood grayscales around the center; Step 22: Substitute each neighborhood grayscale into the screen characteristic parameters to calculate the neighborhood CIE color coordinates corresponding to each neighborhood grayscale; Step 23: Calculate the color difference between each neighborhood CIE color coordinate and the target CIE color coordinate, and find the minimum color difference therebetween; Step 24: When the minimum color difference is not greater than the tolerance value, confirm that the neighborhood grayscale corresponding to the minimum color difference has been correctly calibrated, and output the neighborhood grayscale corresponding to the minimum color difference as a calibration result.

3. The calibration method according to claim 2, characterized in that: When the minimum color difference is greater than the tolerance value, the calibration method further includes: Step 25: Taking the neighborhood grayscale corresponding to the minimum color difference as the new center, looping steps 21 to 25 until the calculated minimum color difference is no greater than the tolerance value, and outputting the neighborhood grayscale corresponding to the minimum color difference as the calibration result.

4. The calibration method according to claim 1, characterized in that: The measuring of the screen characteristic parameters of the screen to be calibrated specifically includes: using a colorimeter to measure the screen characteristic parameters of the screen to be calibrated.

5. The calibration method according to claim 1, characterized in that: The establishing of the screen color feature fitting equation according to the screen feature parameters comprises: The following characteristic equation is established: Among them, X, Y, Z represent CIE color coordinate parameters, R, G, B represent grayscale parameters, and a r～t ~j r～t represents the fitting parameters; Substitute the grayscales and the CIE color coordinates corresponding to each grayscale into the characteristic equation to calculate a r～t ~j r～t , and obtain the screen color feature fitting equation.

6. The calibration method according to claim 1, characterized in that: Substituting the pre-calibrated grayscale into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale comprises: The pre-calibrated grayscale is substituted into the screen characteristic parameters, and the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale are estimated by using a tetrahedral interpolation method, a triangular prism method or a trilinear method.

7. The calibration method according to claim 1, characterized in that: Calculating the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates includes: The Delta-E and / or the JNCD between the target CIE color coordinates and the pre-calibrated CIE color coordinates are calculated.

8. The calibration method according to claim 2, characterized in that: The selecting of several neighborhood grayscales around the center comprises: Select several grayscales around the center in six directions of (1, 0, 0), (0, 1, 0), (0, 0, 1), (-1, 0, 0), (0, -1, 0), and (0, 0, -1) as the several neighborhood grayscales.

9. A screen color gamut calibration device, characterized in that: include: A screen characteristic parameter measurement module, used to measure the screen characteristic parameters of the screen to be calibrated, wherein the screen characteristic parameters include a plurality of grayscales and the CIE color coordinates corresponding to each grayscale; A characteristic equation fitting module is used to establish a screen color characteristic fitting equation according to the screen characteristic parameters, specifically: establish a characteristic equation, substitute the measured grayscale and the CIE color coordinates corresponding to each grayscale into the characteristic equation, calculate the fitting parameters, and obtain the screen color characteristic fitting equation; A target CIE color coordinate setting module, used to set the target CIE color coordinates for the screen to be calibrated; A pre-calibrated grayscale calculation module, used for substituting the target CIE color coordinates into the screen color feature fitting equation to calculate the pre-calibrated grayscale; A pre-calibrated CIE color coordinate calculation module, used for substituting the pre-calibrated grayscale into the screen characteristic parameters to estimate the pre-calibrated CIE color coordinates corresponding to the pre-calibrated grayscale; A color difference calculation module, used to calculate the color difference between the target CIE color coordinates and the pre-calibrated CIE color coordinates; A calibration result output module, used for confirming that the pre-calibrated grayscale has been correctly calibrated when the color difference is not greater than a preset tolerance value, and outputting the pre-calibrated grayscale as a calibration result; When the color difference is greater than the tolerance value, it is determined that the pre-calibrated grayscale is unqualified.

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