LED calibration test method and device based on image processing

Abstract

The present application relates to a kind of LED calibration test method based on image processing, propose using camera combined with image processing instead of LED analyzer and motor system test mode.By studying the relationship between LED luminous image information and actual luminous parameters, model is established to construct mapping from image information to actual luminous parameters, finally using the luminous parameters obtained in combination with related influencing factors to correct the duty cycle of each primary color of target color, so that the luminous parameters of calibrated LED are closer to target value.The present application collects primary color, each time all LED lamp beads on the lamp panel under test are lit at a time for collection, test target color, each time all LED lamp beads on the lamp panel under test are lit at a time for collection, industrial camera replaces professional photometric equipment and motor system, reduces equipment cost, and corrects calibration result according to the nonlinear relationship between LED forward current and luminous intensity, so that the color difference between calibration result and target color is smaller.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED lamp, and particularly to an LED calibration test method and device based on image processing. BACKGROUND

[0002] At present, professional light measurement equipment is used for color LED calibration, and a motor moving mechanism and an upper computer algorithm are used for implementation.

[0003] The test method of moving a light measurement probe by a motor system to collect LED color information to be measured has three problems: first, the test method, single-step serial test can only test a single LED, which is low in efficiency; second, the positioning accuracy problem, the probe depends on the positioning accuracy of the motor moving system, the size of the probe and the LED is relatively low in fault tolerance, and misalignment can easily lead to test failure; third, the algorithm accuracy problem, the calibration algorithm accuracy is not high, and the measured LED after calibration still has a large color difference.

[0004] There is an urgent need in the market to propose an LED calibration test method to improve the limitations of the current test method and test system. SUMMARY

[0005] The present application aims to at least solve one of the problems of the prior art, and provides an LED calibration test method and device based on image processing.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] Specifically, an LED calibration test method based on image processing is proposed, which comprises the following steps:

[0008] Step 110, N images are obtained by acquiring an image of a to-be-tested lamp panel placed under a preset condition when each single-channel is lit, and N is consistent with the number of channels of the to-be-tested lamp panel lamp beads;

[0009] Step 120, LED lamp bead positioning is performed based on the N images to obtain the final coordinates of each LED lamp bead;

[0010] Step 130, image cutting is performed on one of the N images based on the final coordinates of each LED lamp bead to obtain a sub-image of each LED lamp bead;

[0011] Step 140, the chrominance parameters of each LED lamp bead when the current image corresponds to single-channel lighting are obtained based on the sub-image of each LED lamp bead;

[0012] Step 150, steps 130 to 140 are repeated until the N images are processed to obtain the chrominance parameters of each LED lamp bead when different single-channel lighting is performed;

[0013] Step 160, calculating the channel components of each LED lamp bead based on the chrominance parameters when each LED lamp bead is lit at different single-channel points;

[0014] Step 170, correcting the calculated channel components according to the non-linear relationship between the forward current and the luminous intensity of the LED lamp bead to obtain the final channel components, i.e., the channel duty cycles;

[0015] Step 180, performing target color testing of the LED lamp bead on the to-be-tested lamp panel based on the channel duty cycles to obtain the testing result.

[0016] Further, specifically, the preset conditions of the to-be-tested lamp panel when placed include,

[0017] In the optical darkroom, the industrial camera is fixed, the to-be-tested lamp panel is placed parallel to the lens plane of the industrial camera at a position with a focal length from the lens plane, the center point of the to-be-tested lamp panel is coincided with the lens focal point, and the spacing between the LED lamp beads on the to-be-tested lamp panel should not be less than the corresponding side length of the light-emitting surface.

[0018] Further, specifically, when the to-be-tested lamp panel is a three-channel one, N is 3, and at this time, the full red image of the to-be-tested lamp panel, the full green image of the to-be-tested lamp panel, and the full blue image of the to-be-tested lamp panel need to be collected; when the to-be-tested lamp panel is a four-channel one, N is 4, and in addition to the above-mentioned three kinds of images, the full white image of the to-be-tested lamp panel also needs to be collected.

[0019] Further, specifically, the final coordinates of each LED lamp bead are obtained based on the N images, including,

[0020] The final coordinates of the current LED lamp bead are obtained by averaging the coordinate results of the same LED lamp bead in each of the N images, and the above-mentioned operation is repeatedly executed until the final coordinates of each LED lamp bead are obtained by positioning each LED lamp bead.

[0021] Further, specifically, the sub-image of each LED lamp bead is obtained by image cutting, including,

[0022] For each LED lamp bead, a search is performed along the diagonal line passing through the final coordinates thereof, and the region with a pixel value greater than or equal to half of the pixel value at the final coordinates is cut, and the specific cutting method is as follows,

[0023] Assuming the pixel value at the final coordinate is P, starting from the final coordinate, search for nearby pixels along the upper left (both horizontal and vertical coordinates are reduced by one) and lower right (both horizontal and vertical coordinates are increased by one). After finding the pixel with the closest pixel value to 0.5P, sum the distances of these two pixels from the final coordinate and take the average value l. Cut out a square area with a diagonal length of 2l centered on the final coordinate, which is the sub-image of the LED bead corresponding to the final coordinate.

[0024] Furthermore, the method also includes performing pixel value compensation on the sub-images after cutting out each LED bead, wherein the compensation method is as follows:

[0025] The straight-line distance from the final coordinates to the center point of the light board under test and the vertical distance between the light board under test and the industrial camera are obtained. The straight-line distance is then substituted into the light brightness attenuation model as light travels through the air with distance to obtain an attenuation value. The attenuation value is then used to compensate for the pixel value of each pixel in the sub-image of the LED bead corresponding to the final coordinates.

[0026] Furthermore, the chromaticity parameters of each LED bead when the corresponding single channel is lit in the current image are calculated, including:

[0027] Based on the final coordinates of the LED beads and the actual imaging effect of the testing equipment and environment, the pixel weights in the sub-image of the LED beads cut out when the current channel is lit are preset. The primary color value is obtained by weighted averaging of the pixel values ​​and weights of the pixels in the sub-image of the LED beads. The primary color value is input into the mapping model to calculate the primary color information of the current LED bead in the current channel. Finally, the brightness and color coordinate information are calculated based on the primary color information.

[0028] Furthermore, the calculated channel components are corrected to obtain the final channel components, i.e., the duty cycle of each channel, including...

[0029] The calculated luminous intensity of each channel component is substituted into the nonlinear relationship curve between the forward current and luminous intensity of the LED bead to obtain the forward current value corresponding to each channel component. Finally, the ratio of the forward current value to the drive current value at full output is used as the final duty cycle of each channel.

[0030] Furthermore, specifically, based on the duty cycle of each channel, the target color of the LED chips in the test panel is tested, and the test results are obtained, including...

[0031] The color difference between the LED beads of the test board and the target color when the LEDs are lit is calculated based on the final duty cycle of each channel. If the color difference exceeds the preset maximum allowable color difference, the test board is deemed unqualified; otherwise, it is deemed qualified.

[0032] The application further provides an LED calibration test device based on image processing, which comprises the following:

[0033] A data acquisition module is configured to acquire N images of a to-be-tested lamp panel placed under a preset condition and illuminated at each single-channel point, wherein N is consistent with the number of channels of LED lamp beads of the to-be-tested lamp panel.

[0034] An LED lamp bead positioning module is configured to position LED lamp beads based on the N images to obtain final coordinates of each LED lamp bead.

[0035] An image cutting module is configured to cut an image of the N images based on the final coordinates of each LED lamp bead to obtain a sub-image of each LED lamp bead.

[0036] A chroma parameter calculation module is configured to obtain chroma parameters of each LED lamp bead when the to-be-tested lamp panel is illuminated at a single channel corresponding to the current image based on the sub-image of each LED lamp bead.

[0037] A chroma parameter statistical module is configured to repeatedly run the image cutting module and the chroma parameter calculation module until the N images are processed to obtain chroma parameters of each LED lamp bead when the to-be-tested lamp panel is illuminated at different single channels.

[0038] A channel component calculation module is configured to calculate channel components of each LED lamp bead based on the chroma parameters of each LED lamp bead when the to-be-tested lamp panel is illuminated at different single channels.

[0039] A correction module is configured to correct the calculated channel components based on a nonlinear relationship between a forward current and luminous intensity of the LED lamp bead to obtain final channel components, i.e., channel duty cycles.

[0040] A test module is configured to perform target color testing of LED lamp beads of the to-be-tested lamp panel based on the channel duty cycles to obtain a test result.

[0041] The application has the following advantages:

[0042] The application provides an LED calibration test method based on image processing, which uses a camera combined with image processing to replace the test mode of an LED analyzer and a motor system. By studying the relationship between LED light-emitting image information and actual light-emitting parameters, a model is established to map the image information to the actual light-emitting parameters, and finally the obtained light-emitting parameters are used in combination with related influencing factors to correct the duty cycles of each primary color of the target color, so that the light-emitting parameters of the calibrated LED are closer to the target value, and the following advantages are achieved:

[0043] 1. When collecting primary colors, all LED beads on the test board are lit up at the same time for each collection. Compared with the traditional method of lighting up LED beads one by one by moving the probe with a motor and collecting data, the test time is significantly shortened and the efficiency is significantly improved.

[0044] 2. When testing the target color, the target color of all LED beads on the test board is collected at the same time. Compared with the traditional method of moving the probe by motor to light up the LED beads one by one and collecting the data, the test time is significantly shortened and the efficiency is significantly improved.

[0045] 3. No motor system is required, thus avoiding the problem of misalignment. It avoids the positioning accuracy problem caused by the reliance on the motor movement system for the probe in traditional methods. The probe and LED size have relatively low fault tolerance and are prone to test failure due to misalignment.

[0046] 4. No motor system is required, so there is no risk of probe collision. This avoids the situation in traditional methods where the probe can perform three-dimensional movement with a motor system, and the probe may collide with the LED if the Z-axis height is not set properly or the LED to be measured is not placed in the fixture.

[0047] 5. Industrial cameras replaced professional light metering equipment and motor systems, reducing equipment costs;

[0048] 6. The calibration results are corrected based on the nonlinear relationship between LED forward current and luminous intensity, so that the color difference between the calibration results and the target color is smaller. Attached Figure Description

[0049] The above and other features of this disclosure will become more apparent from the detailed description of the embodiments shown in conjunction with the accompanying drawings. In the accompanying drawings, the same reference numerals denote the same or similar output voltages. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort. In the drawings:

[0050] Figure 1 The diagram shows a flowchart of an LED calibration test method based on image processing according to the present invention.

[0051] Figure 2 The diagram shows the positions of the industrial camera and the LED board under test in an optical darkroom for an LED calibration test method based on image processing according to the present invention.

[0052] Figure 3-a as well as Figure 3-b The diagram shows the distribution of LED beads on the test board in two different embodiments of the LED calibration test method based on image processing according to the present invention.

[0053] Figure 4 Fig. 1 shows a cutting diagram of a lamp panel image in a LED calibration test method based on image processing according to the present application;

[0054] Figure 5 Fig. 2 shows a graph of the relationship between the luminous intensity and the forward current of an LED lamp used in a LED calibration test method based on image processing according to the present application;

[0055] Figure 6 Fig. 3 shows a test result display diagram of an embodiment of a LED calibration test method based on image processing according to the present application. DETAILED DESCRIPTION

[0056] The concept, specific structure and generated technical effects of the present application will be described clearly and completely in combination with embodiments and the accompanying drawings, so as to fully understand the purpose, scheme and effects of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The same reference signs used in the drawings indicate the same or similar parts.

[0057] First, some terms appearing in the present application are explained as follows:

[0058] The LED is the full name of Light Emitting Diode, which means light emitting diode.

[0059] The industrial camera includes a camera used in the industrial field made of a CCD or CMOS device.

[0060] The CCD is the full name of Charge Coupled Device, which means charge coupled device.

[0061] The CMOS is the full name of Complementary Metal Oxide Semiconductor, which means complementary metal oxide semiconductor device.

[0062] The sRGB color standard is the full name of standard Red Green Blue color standard, which is a general color standard developed by Microsoft.

[0063] The CIE1931-XYZ color space refers to a color space defined by mathematics published by the International Commission on Illumination (CIE) in 1931.

[0064] Referring to Figure 1 , example 1, the present application proposes a LED calibration test method based on image processing, which includes the following:

[0065] Step 110, obtaining N images of the to-be-tested lamp panel placed under preset conditions when each single-channel is lit, N being consistent with the number of channels of the lamp beads of the to-be-tested lamp panel;

[0066] Step 120, performing LED lamp bead positioning based on the N images to obtain the final coordinates of each LED lamp bead;

[0067] Step 130, performing image cutting on one of the N images based on the final coordinates of each LED lamp bead to obtain a sub-image of each LED lamp bead;

[0068] Step 140, obtaining the chrominance parameters of each LED lamp bead when the current image corresponds to single-channel lighting based on the sub-image of each LED lamp bead respectively;

[0069] Step 150, repeating steps 130 to 140 until the N images are processed to obtain the chrominance parameters of each LED lamp bead when different single-channel lighting is performed;

[0070] Step 160, calculating the channel components of each LED lamp bead based on the chrominance parameters of each LED lamp bead when different single-channel lighting is performed;

[0071] In the calculation, the chrominance parameters of full red, full green and full blue are obtained, and then linear equations about the three components of full red, full green and full blue are listed according to the chrominance parameters of the target color based on the superposition principle of color light, and are solved. If the lamp bead is four-channel, the chrominance parameters of full red, full green, full blue and full white are obtained, and then linear equations about the four components of full red, full green, full blue and full white are listed according to the chrominance parameters of the target color based on the superposition principle of color light, and are solved. The specific solving process is a common means for those skilled in the art, and therefore is not described in detail;

[0072] Step 170, correcting the calculated channel components according to the non-linear relationship between the forward current of the LED lamp bead and the luminous intensity to obtain the final channel components, i.e., the channel duty cycles. The non-linear relationship between the forward current of the LED lamp bead and the luminous intensity is obtained by actual measurement in an optical laboratory;

[0073] Step 180, performing target color testing of the LED lamp bead of the to-be-tested lamp panel based on the channel duty cycles to obtain a test result.

[0074] The application proposes to use a camera combined with image processing to replace the LED analyzer and motor system test mode. By studying the relationship between the LED light image information and the actual light parameters, a model is established to map the image information to the actual light parameters. Finally, the obtained light parameters are combined with the related influencing factors to correct the duty cycle of each primary color of the target color, so that the light parameters of the calibrated LED are closer to the target value.

[0075] Reference Figure 2 As a preferred embodiment of the application, specifically, the preset conditions of the to-be-tested lamp panel when placed include,

[0076] In the optical darkroom, the industrial camera is fixed, the to-be-tested lamp panel is placed parallel to the lens plane of the industrial camera at a position with a focal length from the lens plane, the center point of the to-be-tested lamp panel is coincided with the lens focal point, and the spacing between the LED lamp beads on the to-be-tested lamp panel should be greater than or equal to the corresponding side length of the light-emitting surface.

[0077] In the preferred embodiment, the to-be-tested lamp panel refers to a PCB on which a plurality of to-be-tested LED lamp beads are attached or a test fixture on which a plurality of LEDs are fixed, and the layout is shown in FIG. 3. The spacing between the LED lamp beads on the to-be-tested lamp panel should be greater than or equal to the corresponding side length of the light-emitting surface. For example, if the light-emitting surface of the LED lamp bead is rectangular (for example, Figure 3-a ), the lengths of the x and y sides are a and b respectively, and the lamp beads are arranged in a matrix on the to-be-tested panel, then the spacing Δx of the lamp beads in the direction parallel to the x side of the to-be-tested lamp panel should be greater than or equal to a, and the spacing Δy of the lamp beads in the direction parallel to the y side of the to-be-tested lamp panel should be greater than or equal to b. If the light-emitting surface of the LED lamp bead is circular (for example, Figure 3-b ), then the lengths of the above x and y sides are both the diameter d of the circle, and the spacings Δx and Δy of the lamp beads in the upward direction of the to-be-tested lamp panel should both be greater than or equal to d.

[0078] As a preferred embodiment of the application, specifically, when the to-be-tested lamp panel is a three-channel one, N is 3, at this time, the full red image of the to-be-tested lamp panel, the full green image of the to-be-tested lamp panel and the full blue image of the to-be-tested lamp panel need to be collected; when the to-be-tested lamp panel is a four-channel one, N is 4, in addition to the above three kinds of images, the full white image of the to-be-tested lamp panel also needs to be collected.

[0079] In the preferred embodiment, first, the full red of all the lamp beads on the to-be-tested lamp panel is lit at the same time, and the full red image is collected; then, the full green of all the lamp beads on the to-be-tested lamp panel is lit at the same time, and the full green image is collected; then, the full blue of all the lamp beads on the to-be-tested lamp panel is lit at the same time, and the full blue image is collected; if the lamp bead is a four-channel one, finally, the full white of all the lamp beads on the to-be-tested lamp panel is lit at the same time, and the full white image is collected.

[0080] As a preferred embodiment of the present application, specifically, the LED lamp bead positioning based on N images obtains the final coordinates of each LED lamp bead, including,

[0081] The final coordinates of the current LED lamp bead are obtained by averaging the coordinate results of the same LED lamp bead in each of the N images, and the above operation is repeatedly performed until the final coordinates of each LED lamp bead are obtained by positioning each LED lamp bead.

[0082] In the present preferred embodiment, considering that the LED lamp bead may deviate slightly in multiple images, the average of the LED lamp bead coordinates in multiple images is taken as the actual coordinates to eliminate the deviation to some extent.

[0083] As a preferred embodiment of the present application, specifically, the image cutting obtains the sub-image of each LED lamp bead, including,

[0084] For each LED lamp bead, search along the diagonal line passing through the final coordinates, and cut the region with a pixel value greater than or equal to half of the pixel value at the final coordinates, and the specific cutting method is as follows,

[0085] Suppose the pixel value at the final coordinates is P, search the nearby pixels from the final coordinates along the left-up direction (both horizontal and vertical coordinates are reduced by one) and the right-down direction (both horizontal and vertical coordinates are increased by one), and after searching the pixel with a pixel value closest to 0.5P, sum the distances of the two pixels from the final coordinates and take the average l. Cut the square region with the final coordinates as the center and the diagonal length of 2l, which is the sub-image of the LED lamp bead corresponding to the final coordinates.

[0086] As a preferred embodiment of the present application, the method further includes, after cutting the sub-image of each LED lamp bead, the sub-image is also subjected to pixel value compensation, and the compensation method is,

[0087] Based on the distance from the final coordinates to the center point of the lamp panel to be measured and the vertical distance from the lamp panel to be measured to the industrial camera, the straight-line distance from the final coordinates to the industrial camera is obtained, the attenuation value is obtained by bringing the straight-line distance into the decay model of the light intensity in air, and the attenuation value is compensated to the pixel value of each pixel point in the sub-image of the LED lamp bead corresponding to the final coordinates.

[0088] In the present preferred embodiment, considering the influence of light attenuation, the pixel value is compensated based on this. Since the light intensity in air propagation follows the inverse square decay, the square of the straight-line distance is taken as the compensation coefficient, and the value obtained by multiplying the attenuation coefficient by the pixel value of each pixel point in the sub-image of the LED lamp bead corresponding to the final coordinates and performing normalization processing is taken as the compensated sub-image pixel value.

[0089] As a preferred embodiment of the present application, the chrominance parameters of each LED lamp bead when a single channel is lit in the current image are calculated, including,

[0090] According to the final coordinates of the LED lamp bead, the actual imaging effect of the test equipment and the test environment is combined to pre-set the pixel point weight in the cut-out LED lamp bead sub-image when the current channel is lit, the primary color value is obtained by weighted average of the pixel value and the weight of the pixel point in the LED lamp bead sub-image, the base color information of the current LED lamp bead in the current channel is calculated by inputting the base color value into the mapping model, and finally the brightness and color coordinate information are calculated according to the base color information.

[0091] In the preferred embodiment, the mapping model refers to a model for mapping the base color value to the corresponding component in the sRGB color standard.

[0092] As a preferred embodiment of the present application, the calculated channel components are corrected to obtain the final channel components, i.e., the duty cycles of each channel, including,

[0093] The calculated channel components, i.e., the required luminous intensity of each channel, are brought into the non-linear relationship curve between the forward current and the luminous intensity of the LED lamp bead to obtain the forward current value corresponding to each channel component, and finally the ratio of the forward current value to the driving current value at full output is taken as the final duty cycle of each channel.

[0094] In the preferred embodiment, it is considered that there is a premise assumption in step 160 for calculating the channel components: the forward current and the luminous intensity of the LED are in linear relationship when the LED is in the working zone, but this assumption does not hold true in the actual calibration test process, so the non-linear relationship between the forward current and the luminous intensity of the LED lamp bead used is considered to correct the calculated channel components. Figure 5

[0095] As a preferred embodiment of the present application, specifically, the target color test of the LED lamp bead is performed on the to-be-tested lamp panel based on the duty cycle of each channel, and the test result is obtained, including,

[0096] The color difference between the LED lamp bead of the to-be-tested lamp panel and the target color when lit is calculated based on the final duty cycle of each channel, and if it exceeds the pre-set maximum allowable color difference, it is determined as unqualified, otherwise it is determined as qualified.

[0097] In the preferred embodiment, considering the visualization of the determination result, the test results of each LED on the lamp panel are marked and displayed through an image, as shown in Figure 6 The white color represents no test (not shown in the figure because there is no test), the red color represents test failure (the red color in the figure represents the test failure), and the green color represents test success (the green color in the figure represents the test success). Figure 6 ​Green represents the test is qualified (the second point from the left in the lower row is darker in color) Figure 6 Yellow represents the test is abnormal (the second point from the right in the lower row is lighter in color). Figure 6 Yellow represents the test is abnormal (the second point from the right in the lower row is lighter in color).

[0098] The application further provides an LED calibration test device based on image processing, comprising the following:

[0099] A data acquisition module is configured to acquire N images of a to-be-tested lamp panel placed under a preset condition when each single-channel point is lighted, wherein N is consistent with the number of channels of lamp beads of the to-be-tested lamp panel.

[0100] An LED lamp bead positioning module is configured to position the LED lamp beads based on the N images to obtain final coordinates of each LED lamp bead.

[0101] An image cutting module is configured to cut an image of the N images based on the final coordinates of each LED lamp bead to obtain a sub-image of each LED lamp bead.

[0102] A chroma parameter calculation module is configured to obtain chroma parameters of each LED lamp bead when the current image corresponds to single-channel lightening based on the sub-image of each LED lamp bead.

[0103] A chroma parameter statistical module is configured to repeatedly run the image cutting module and the chroma parameter calculation module until the N images are processed to obtain the chroma parameters of each LED lamp bead when different single-channel lightening.

[0104] A channel component calculation module is configured to calculate channel components of each LED lamp bead based on the chroma parameters of each LED lamp bead when different single-channel lightening.

[0105] A correction module is configured to correct the calculated channel components based on a nonlinear relationship between the forward current and the luminous intensity of the LED lamp bead to obtain final channel components, i.e., channel duty cycles.

[0106] A test module is configured to perform target color testing of the LED lamp beads of the to-be-tested lamp panel based on the channel duty cycles to obtain a test result.

[0107] The modules described as separate components can or can not be physically separated, and the components displayed as modules can or can not be physical modules, i.e., can be located in one place or distributed on multiple network modules. According to actual needs, some or all of the modules can be selected to achieve the purpose of the scheme in the embodiment.

[0108] In addition, each function module in each embodiment of the present application can be integrated in one processing module, or each module can be physically present alone, or two or more modules can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software function module.

[0109] When the integrated module is realized in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer-readable storage medium. When the processor executes the computer program, the steps of each method embodiment described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer-readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0110] Although the description of the present application has been quite detailed and particularly described with respect to several embodiments, it is not intended to be limited to any of these details or embodiments or any special embodiment, but should be considered to be a broad interpretation of the prior art by reference to the appended claims, so as to effectively cover the intended scope of the present application. In addition, the present application is described above in embodiments that the inventor can foresee, and the purpose is to provide a useful description, and non-essential modifications to the present application that have not yet been foreseen can still represent equivalent modifications of the present application.

[0111] The above is only a preferred embodiment of the present application, and the present application is not limited to the above-described embodiments, but any technical solution and / or implementation within the scope of the present application should be within the scope of the present application. The technical solution and / or implementation can have various modifications and changes.

Claims

1. An LED calibration test method based on image processing, characterized in that, Including the following: Step 110: Obtain an image of the test panel placed under preset conditions when each single channel is lit, resulting in a total of N images, where N is the same as the number of channels of the test panel's LED beads. Step 120: Based on the N images, locate the LED beads to obtain the final coordinates of each LED bead; Step 130: Based on the final coordinates of each LED bead, perform image segmentation on one of the N images to obtain a sub-image of each LED bead; Step 140: Obtain the chromaticity parameters of each LED when the single channel is lit in the current image based on the sub-image of each LED. Step 150: Repeat steps 130 to 140 until all N images have been processed to obtain the chromaticity parameters of each LED bead when lit in different single channels. Step 160: Calculate the chromaticity parameters of each LED bead when it is lit in different single channels; Step 170: Correct the calculated channel components based on the nonlinear relationship between the forward current and luminous intensity of the LED beads to obtain the final channel components, i.e., the duty cycle of each channel. Step 180: Based on the duty cycle of each channel, perform target color testing on the LED beads of the test board to obtain the test results; Specifically, the calculated channel components are corrected to obtain the final channel components, i.e., the duty cycle of each channel, including... The calculated luminous intensity of each channel component is substituted into the nonlinear relationship curve between the forward current and luminous intensity of the LED bead to obtain the forward current value corresponding to each channel component. Finally, the ratio of the forward current value to the drive current value at full output is used as the final duty cycle of each channel.

2. The LED calibration test method based on image processing according to claim 1, characterized in that, Specifically, the preset conditions for placing the lamp board under test include: Fix the industrial camera in the optical darkroom, and place the lamp board to be tested parallel to the lens plane of the industrial camera at a position at a distance of the focal length from the lens plane, so that the center point of the lamp board to be tested coincides with the focal point of the lens, and ensure that the spacing between the LED beads on the lamp board to be tested is not less than the corresponding side length of the light-emitting surface.

3. The LED calibration test method based on image processing according to claim 1, characterized in that, Specifically, when the light board under test has three channels, N is 3. At this time, it is necessary to collect images of the light board under test as full red, full green, and full blue. When the light board under test has four channels, N is 4. In addition to the above three types of images, it is also necessary to collect images of the light board under test as full white.

4. The LED calibration test method based on image processing according to claim 1, characterized in that, Specifically, based on the N images, the LED beads are located to obtain the final coordinates of each LED bead, including: The average of the coordinates of the same LED bead in each of the N images is used to obtain the final coordinates of the current LED bead. This operation is repeated until each LED bead is located and its final coordinates are obtained.

5. The LED calibration test method based on image processing according to claim 4, characterized in that, Specifically, image segmentation is performed to obtain sub-images for each LED bead, including: For each LED bead, a search is performed along a diagonal line passing through its final coordinates. Regions with pixel values ​​greater than or equal to half the pixel value at those final coordinates are then segmented. The specific segmentation method is as follows. Assuming the pixel value at the final coordinate is P, starting from the final coordinate, search for nearby pixels along the upper left (both horizontal and vertical coordinates are reduced by one) and lower right (both horizontal and vertical coordinates are increased by one). After finding the pixel with the closest pixel value to 0.5P, sum the distances of these two pixels from the final coordinate and take the average value l. Cut out a square area centered at the final coordinate with a diagonal length of 2l, which is the sub-image of the LED bead corresponding to the final coordinate.

6. The LED calibration test method based on image processing according to claim 5, characterized in that, The method further includes, after obtaining the sub-image of each LED bead, performing pixel value compensation on the sub-image, wherein the compensation method is as follows: The straight-line distance from the final coordinates to the center point of the light board under test and the vertical distance between the light board under test and the industrial camera are obtained. The straight-line distance is then substituted into the light brightness attenuation model as light travels through the air with distance to obtain an attenuation value. The attenuation value is then used to compensate for the pixel value of each pixel in the sub-image of the LED bead corresponding to the final coordinates.

7. The LED calibration test method based on image processing according to claim 1, characterized in that, Calculate the chromaticity parameters of each LED when its corresponding single channel is lit in the current image, including: The primary color value is obtained by weighted averaging of the pixels in the sub-image of the LED bead when the current channel is lit. The primary color value is then input into the mapping model to calculate the primary color information of the current LED bead in the current channel. Finally, the brightness and color coordinate information are calculated based on the primary color information.

8. The LED calibration test method based on image processing according to claim 1, characterized in that, Specifically, based on the duty cycle of each channel, the target color of the LED chips in the test panel is tested, and the test results are obtained, including... The color difference between the LED beads of the test board and the target color when the LEDs are lit is calculated based on the final duty cycle of each channel. If the color difference exceeds the preset maximum allowable color difference, the test board is deemed unqualified; otherwise, it is deemed qualified.

9. An LED calibration and testing device based on image processing, characterized in that, The apparatus comprising the steps of the method according to any one of claims 1-8, wherein the apparatus includes the following: The data acquisition module is used to acquire one image of the test lamp board placed under preset conditions when each single channel is lit, for a total of N images, where N is the same as the number of channels of the lamp beads in the test lamp board. The LED bead positioning module is used to locate the LED beads based on N images to obtain the final coordinates of each LED bead. The image segmentation module is used to segment one of the N images based on the final coordinates of each LED bead to obtain a sub-image of each LED bead; The chromaticity parameter calculation module is used to obtain the chromaticity parameters of each LED when the single channel is lit in the current image based on the sub-image of each LED. The chromaticity parameter statistics module is used to repeatedly run the image cutting module and the chromaticity parameter calculation module until the N images are processed to obtain the chromaticity parameters of each LED bead when it is lit in different single channels. The channel component calculation module is used to calculate the channel components of each LED based on the chromaticity parameters of each LED when it is lit in different single channels. The correction module is used to correct the calculated channel components based on the nonlinear relationship between the forward current and luminous intensity of the LED beads to obtain the final channel components, i.e., the duty cycle of each channel. The testing module is used to test the target color of LED beads on the test board based on the duty cycle of each channel, and obtain the test results.

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