Demra adjustment for 2D backlight systems

Abstract

A method for Demla calibration is provided. The method includes obtaining multiple luminance maps of multiple light sources in a two-dimensional backlight system for multiple test patterns. Each test pattern indicates whether each of the multiple light sources is on or off. Each of the multiple light sources is on in only one of the multiple test patterns. The multiple luminance maps indicate the luminance levels of the multiple light sources for the multiple test patterns. The method further includes generating a cumulative luminance map by summing the multiple luminance maps. The method further includes generating Demla correction coefficients for the multiple light sources based on the cumulative luminance map.

Description

TECHNICAL FIELD

[0001] Cross-reference to Related Applications: This application claims priority to U.S. Patent Application No. 18 / 798,005, filed August 8, 2024, entitled "Demura Adjustment for 2D Backlight Systems", and U.S. Provisional Patent Application No. 63 / 590,868, filed October 17, 2023, entitled "Demura Adjustment for 2D Backlight Systems". These applications are incorporated herein by reference in their entireties.

[0002] The present disclosure relates generally to demura adjustment for two-dimensional (2D) backlight systems.

BACKGROUND ART

[0003] A local dimming function based on a two-dimensional (2D) backlight is one of the techniques for enhancing the contrast of liquid crystal display (LCD) devices. Local dimming technology can achieve high dynamic contrast and low power consumption by individually controlling each light source (e.g., light emitting diode (LED)) of the 2D backlight system according to input image data.

[0004] The image quality of an LCD device with a local dimming function may heavily depend on the characteristics of the light sources of the backlight system. In LCD devices with a local dimming function, one of the major issues is that variations in the optical properties of each light source may lead to reduced luminance uniformity.

[0005] The demura function is a luminance correction technique used to improve the luminance uniformity of LCD devices equipped with a two-dimensional backlight system. The demura function may operate by applying a demura correction factor to the luminance value of each light source, where the demura correction factor is determined based on the characteristics of each light source. The demura correction factor may be stored in the LCD device as demura data used to correct image mura in the LCD device.

[0006] Depending on the embodiment, the demla correction coefficient for each light source may be determined during the adjustment or calibration process of the LCD device. The adjustment process may include operating each light source of the two-dimensional backlight system to illuminate the LCD panel according to a predetermined test pattern and obtaining a luminance map on the LCD panel for each test pattern. The demla correction coefficient for each light source may be determined based on the obtained luminance map.

[0007] This summary is provided to introduce a selection of concepts that will be further detailed below in a simplified form. This summary is not intended to identify any key or essential features of the disclosure. The disclosure may include the following various aspects and embodiments.

[0008] In one embodiment, the present disclosure provides a method which includes obtaining multiple luminance maps of multiple light sources of a two-dimensional backlight system for a plurality of test patterns. Each test pattern indicates whether each of the plurality of light sources is turned on or off. Each of the plurality of light sources is turned on in only one of the plurality of test patterns. The plurality of luminance maps indicate the luminance levels of the plurality of light sources for the plurality of test patterns. The method further includes generating a cumulative luminance map by summing the plurality of luminance maps. The method further includes generating a demla correction coefficient for the plurality of light sources based on the cumulative luminance map.

[0009] In another embodiment, the disclosure provides a calibration system including a processor and a memory device. The memory device is configured to store a computer executable instruction that, at runtime, causes the processor to acquire multiple luminance maps of multiple light sources in a two-dimensional backlight system for a plurality of test patterns. Each test pattern indicates whether each of the multiple light sources is turned on or off. Each of the multiple light sources is turned on in only one of the multiple test patterns. The multiple luminance maps indicate the luminance levels of the multiple light sources for the plurality of test patterns. The computer executable instruction further causes the processor to create a cumulative luminance map by summing the luminance maps and to generate demla correction coefficients for the multiple light sources based on the cumulative luminance map.

[0010] In yet another embodiment, the Disclosure provides a non-temporary tangible computer-readable storage medium for demura calibration of a display device comprising a two-dimensional backlight system. The non-temporary tangible computer-readable storage medium stores computer-executable instructions that cause a processor to acquire multiple luminance maps of multiple light sources of the two-dimensional backlight system for a plurality of test patterns. Each test pattern indicates whether each of the multiple light sources is turned on or off. Each of the multiple light sources is turned on in only one of the multiple test patterns. The multiple luminance maps indicate the luminance levels of the multiple light sources for the plurality of test patterns. The computer-executable instructions further cause the processor to create a cumulative luminance map by summing the luminance maps and generate demura correction coefficients for the multiple light sources based on the cumulative luminance map. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows an example configuration of a display device that supports local dimming functionality according to one or more embodiments.

[0012] [Figure 2]Figure 2 shows an example of a side view configuration of the display device shown in Figure 1 according to one or more embodiments.

[0013] [Figure 3] Figure 3 shows an example of the arrangement of light sources of a 2D backlight system according to one or more embodiments.

[0014] [Figure 4] Figure 4 shows an example of a test pattern used to measure the light diffusion characteristic of each light source according to one or more embodiments.

[0015] [Figure 5] Figure 5 shows an example of the light diffusion characteristic obtained by a fitting procedure according to one or more embodiments.

[0016] [Figure 6] Figure 6 shows an example of the contribution from surrounding light sources to the total luminance of the zone corresponding to the central light source according to one or more embodiments.

[0017] [Figure 7] Figure 7 shows an example of a test pattern used to illuminate a display panel and measure the luminance level of each light source according to one or more embodiments.

[0018] [Figure 8] Figure 8 shows an example of an image captured using the four test patterns shown in Figure 7 according to one or more embodiments

[0019] [Figure 9] Figure 9 shows an example of a process for creating a cumulative luminance map of the entire light source array according to one or more embodiments.

[0020] [Figure 10] Figure 10 shows an exemplary scheme for generating Demura correction coefficients according to one or more embodiments.

[0021] [Figure 11] FIG. 11 illustrates an exemplary scheme for calculating a corrected luminance map according to one or more embodiments.

[0022] [Figure 12] FIG. 12 illustrates an exemplary configuration of a calibration system according to one or more embodiments.

[0023] [Figure 13] FIG. 13 illustrates an exemplary configuration of a display driver according to one or more embodiments.

[0024] For ease of understanding, the same reference numerals are used, wherever possible, for elements common to the respective drawings. It is assumed that elements disclosed in one embodiment may be utilized in other embodiments without specific recitation. Subscripts may be added to reference numerals to distinguish elements from one another. The drawings referred to in this specification should not be understood as being to scale unless specifically stated otherwise. Further, the drawings are often simplified, with details and components omitted for clarity of presentation and description. The drawings and description are provided to explain the principles discussed below. [Description of Embodiments]

[0025] The following detailed description is inherently exemplary, and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the foregoing background, brief summary of the drawings, or the following detailed description.

[0026] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the disclosed technology. However, it will be apparent to those skilled in the art that the disclosed technology may be practiced without these specific details. In addition, well-known configurations have not been described in detail to avoid unnecessarily complicating the description.

[0027] As used herein, the term “combined” means directly connected or connected via one or more intervening components or circuits. Furthermore, throughout this application, ordinal numbers (e.g., 1st, 2nd, 3rd, etc.) may be used as adjectives for elements (i.e., any noun in this application). The use of ordinal numbers does not imply or establish a particular order of elements, nor does it limit any element to a single element unless explicitly disclosed by terms such as “preceding,” “following,” and “single” and their synonyms. Rather, the use of ordinal numbers is for distinguishing elements. For example, the first element is distinct from the second element, the first element may encompass multiple elements, and in the ordering of elements, it may follow (or precede) the second element.

[0028] Figure 1 shows an example configuration of a display device 1000 configured to support local dimming functionality according to one or more embodiments. The display device 1000 comprises a liquid crystal display (LCD) panel 100, a two-dimensional (2D) backlight system 200, and a display driver 300. The 2D backlight system 200 is configured to illuminate the display panel 100. The 2D backlight system 200 includes an array of light sources 210. In Figure 1, the light sources 210 are shown with dashed lines because, as shown in Figure 2, which shows a side view configuration of the display device 1000, the light sources 210 are located behind the display panel 200. Although 64 light sources 210 are shown in Figure 1, those skilled in the art will understand that the 2D backlight system 200 may have more or fewer light sources 210 than 64. In actual implementations, the 2D backlight system 200 may include hundreds or thousands of light sources 210. In one embodiment, each light source 210 may include an LED or a different type of light source.

[0029] Figure 3 shows an example of the arrangement of light sources 210 in a 2D backlight system 200 according to one or more embodiments. In the illustrated embodiment, the display panel 100 is divided into rectangular (e.g., square) zones 110 arranged in a row, and the light sources 210 are positioned behind each corresponding zone 110. Each light source 210 is positioned such that its projection onto the display panel 100 is located at the center (e.g., the geometric center) of the corresponding zone 110. Here, the "corresponding zone" 110 of a light source 210 refers to the zone 110 that includes the projection of that light source 210 onto the display panel 100. It should be noted that, due to the light diffusion characteristics of the light sources 210, each light source 210 primarily illuminates its corresponding zone 110, but may secondarily illuminate at least a portion of the surrounding (e.g., adjacent) zones 110.

[0030] Referring to Figure 1, the display driver 300 is configured to receive input image data representing an input image from an external image source (not shown) and to drive the display panel 100 to display the image corresponding to the input image data. The input image data may include pixel data for each pixel of the input image. The pixel data for a certain pixel may include the gradation of each primary color (e.g., red (R), green (G), blue (B)).

[0031] The display driver 300 is further configured to perform a local dimming function by individually controlling each light source 210 of the 2D backlight system 200 according to the input image data. The local dimming function may determine the base luminance value of each light source 210 based on the input image data. The base luminance value of each light source 210 may correspond to a desired luminance level for that light source 210. The base luminance value of a particular light source 210 may be determined based on the pixel data of pixels located in the corresponding zone 110 of that light source 210. In some embodiments, the base luminance value of the particular light source 210 may be further determined based on the pixel data of pixels located in at least a portion of the zone 110 adjacent to the corresponding zone 110 of that light source 210.

[0032] The display driver 300 is further configured to perform a demla function when controlling the light sources 210 of the 2D backlight system 200. In one embodiment, the display driver 300 may be configured to store demla data including a demla correction coefficient, and to apply the stored demla correction coefficient to the base luminance value of each light source 210 to generate a corrected luminance value for each light source 210. The 2D backlight system 200 may be configured so that each light source 210 emits light at a luminance level indicated by the corrected luminance value.

[0033] Demra data may be generated during the adjustment or calibration process of the display device 1000. Various techniques for efficiently determining the demra correction coefficient of the demra data for each light source of the 2D backlight system are disclosed according to various embodiments of this disclosure. Alternatively, the demra data or demra correction coefficient may be generated dynamically during the normal use of the display device 1000.

[0034] In one or more embodiments, the adjustment process for determining the Demla correction coefficient for the light sources of a 2D backlight system may involve evaluating the light diffusion characteristics of each light source 210. Figure 4 shows examples of test patterns used to measure the light diffusion characteristics of each light source 210 according to one or more embodiments. These test patterns are associated with two adjacent light sources and are determined under the assumption that the light sources 210 of the 2D backlight system 200 have identical light diffusion characteristics. The image on the left of Figure 4 shows a first test pattern in which one light source 210 on the left is "lit," the image in the center of Figure 4 shows a second test pattern in which the other light source 210 on the right is "lit," and the image on the right of Figure 4 shows a third test pattern in which both light sources 210 are "lit." White squares in Figure 4 indicate lit light sources 210. The term "lit" may mean that the light source is driven to emit light at a predetermined luminance level (e.g., the maximum allowable luminance level).

[0035] In one or more embodiments, the luminance distributions of single-light source (left and right) and both-light source may be observed using three test patterns, as shown in the left graph of Figure 5. Furthermore, a fitting procedure is performed to estimate the parameters of the distribution function that best fit the light diffusion characteristics of each light source. In one embodiment, a Cauchy distribution fitting procedure may be performed to estimate the parameters of the Cauchy distribution that best fit the light diffusion characteristics of each light source, as shown in the center graph of Figure 5. The right graph of Figure 5 shows an example of the estimated light diffusion characteristics of each light source obtained by the Cauchy distribution fitting procedure.

[0036] Referring to Figure 6, this disclosure recognizes that the total luminance level of a zone corresponding to a given light source (sometimes referred to as a central light source) is the sum of the light outputs of the central light source and its surrounding light sources forming a 3x3 light source array. In the illustrated embodiment, the central light source accounts for approximately 30% of the total luminance level, and the surrounding light sources contribute the remaining approximately 70%. In one or more embodiments, the adjustment process generates a directional filter that represents the light diffusion characteristics of the light sources based on an estimated distribution function (e.g., an estimated Cauchy distribution). This directional filter may represent the respective contributions of the central light source and surrounding light sources of the associated 3x3 light source array to the total luminance level of the zone in question. In one embodiment, the directional filter may include directional coefficients assigned to the central light source and surrounding light sources of the associated 3x3 light source array. An example of a directional filter is shown as a 3x3 matrix in Figure 6. As will be discussed later, the directional filter is used to calculate the luminance correction coefficient for each light source.

[0037] In one or more embodiments, the adjustment process may further involve obtaining a luminance map of the light sources 210. This luminance map may show the luminance level of each light source 210 for the entire light source array. The Demla correction coefficient may be calculated based on this luminance map. One challenge is that, due to the light diffusion characteristics of each light source 210, as described in relation to Figure 6, the measurement results for each light source 210 may be affected by ambient light sources.

[0038] Referring to Figure 7, in order to accurately determine the brightness level of each light source 210, the adjustment process illuminates the display panel using multiple test patterns, each indicating whether to turn on or off one of the multiple light sources. These test patterns are set so that each light source 210 is lit in only one of the test patterns. The adjustment process may take a brightness map of the light source 210 for each of the multiple test patterns and then sum these brightness maps to create a cumulative brightness map. The Demla correction coefficient for each light source is generated based on this cumulative brightness map.

[0039] In one or more embodiments, four test patterns #1, #2, #3, and #4 shown in Figure 7 may be used to illuminate the display panel during the adjustment process. The four test patterns #1, #2, #3, and #4 are determined such that the brightness level of each light source (e.g., LED) does not significantly affect the measurement results of the brightness levels of light sources around it. In one or more embodiments, the four test patterns #1 to #4 may be defined such that each light source is illuminated in only one of the four test patterns #1 to #4. In some embodiments, a first set of light sources 210 may be illuminated in test pattern #1, a second set of light sources 210 may be illuminated in test pattern #2, a third set of light sources 210 may be illuminated in test pattern #3, and a fourth set of light sources 210 may be illuminated in test pattern #4. In such embodiments, the first, second, third, and fourth sets of light sources 210 do not share any light sources, and each light source 210 belongs to only one of the first, second, third, and fourth sets of light sources 210.

[0040] The four test patterns #1 to #4 may be further defined such that each lit light source 210 is surrounded only by or adjacent only to unlit light sources 210. In other words, the four test patterns #1 to #4 may be further defined such that each lit light source 210 is adjacent to unlit light sources 210 in the horizontal, vertical, and diagonal directions. In one embodiment, each lit light source 210 in test pattern #2 is horizontally adjacent to the corresponding lit light source 210 in test pattern #1, each lit light source 210 in test pattern #3 is vertically adjacent to the corresponding lit light source 210 in test pattern #1, and each lit light source 210 in test pattern #4 is diagonally adjacent to the corresponding lit light source 210 in test pattern #1.

[0041] Figure 8 shows examples of images captured using the four test patterns #1, #2, #3, and #4 shown in Figure 7, according to one or more embodiments. These four images may be captured by an imaging device (e.g., a camera) while the display panel 100 is illuminated by the four test patterns #1, #2, #3, and #4. Each captured image shows the luminance level distribution generated by the illuminated light source 210. The upper left image shows an example of the luminance level distribution captured using test pattern #1 shown in Figure 7, and the upper right image shows an example of the luminance level distribution captured using test pattern #2. The lower left image shows an example of the luminance level distribution captured using test pattern #3, and the lower right image shows an example of the luminance level distribution captured using test pattern #4. As shown in Figure 8, the four test patterns #1, #2, #3, and #4 are defined such that the portion of the display panel illuminated by each light source does not overlap with the portion of the display panel illuminated by the other light sources. In one or more embodiments, the captured images are analyzed to generate luminance maps for the four test patterns #1 to #4. Each brightness map shows the brightness level of a lit light source.

[0042] As shown in Figure 9, the cumulative luminance map for the entire light source array is then generated by summing the luminance maps generated for the four test patterns #1 to #4. This cumulative luminance map may show the luminance level of each light source in the entire light source array. The Demla correction coefficient is generated based on the cumulative luminance map thus produced.

[0043] Figure 10 shows an example of a process for generating demura data or demura correction coefficients according to one or more embodiments. This process may include verifying the accuracy of the cumulative luminance map, as shown on the left side of Figure 10. More specifically, a simulated unevenness map may be calculated by applying a directional filter (described in relation to Figure 6) to the cumulative luminance map. This simulated unevenness map simulates the luminance unevenness on the display panel that occurs when the display panel is illuminated by all light sources without the demura function. The simulated unevenness map is compared to an "all-on measurement" luminance map, which is a luminance map generated based on an image taken while the display panel is illuminated by all light sources 210. If the simulated unevenness map is sufficiently similar to the "all-on measurement" luminance map, this indicates that the cumulative luminance map has been successfully generated. In this case, the cumulative luminance map is used to generate demura data, as described below. If there is a significant difference between the simulated unevenness map and the all-light measurement luminance map, the generated cumulative luminance map may be discarded, and the above process of obtaining luminance maps for four test patterns may be repeated to successfully generate the cumulative luminance map.

[0044] The right side of Figure 10 shows an example of a process for generating Demla data or Demla correction coefficients using a cumulative luminance map according to one or more embodiments. The Demla correction coefficients may be determined by the following recursive process: First, an initial set of Demla correction coefficients is determined, and then the corrected luminance map is calculated by applying the initial Demla correction coefficients and a directional filter to the cumulative luminance map. Figure 11 shows an exemplary scheme for calculating the corrected luminance map according to one or more embodiments. In the illustrated embodiment, the luminance level of the light source (x,y) in the corrected luminance map may be calculated according to the following equation (1).

number

[0045] Figure 12 shows an example configuration of a calibration system 2000 configured to perform an adjustment or calibration process to generate demura data and provide it to a display driver 300, according to one or more embodiments. The demura data may include a demura correction coefficient for each light source 210. As described above, the display driver 300 may be configured to perform a local dimming function that determines the base luminance value of each light source 210 based on the input image data. Furthermore, the display driver 300 may be configured to perform a demura function that applies a demura correction coefficient to the base luminance value of each light source 210 to generate a corrected luminance value for each light source 210. The 2D backlight system 200 may be configured such that each light source 210 emits light at a luminance level indicated by the corrected luminance value.

[0046] In one or more embodiments, the calibration system 2000 comprises an imaging device 2100 (e.g., a camera) and a main unit 2200. The imaging device 2100 may be configured to capture an image of the display panel 100 and, based on the captured image, measure the luminance distribution on the display panel 100 for a test pattern. In one or more embodiments, the imaging device 2100 may be configured to (1) measure a first luminance distribution on the display panel 100 while the "left" light source of two related light sources is lit, as shown in the left image of Figure 4; (2) measure a second luminance distribution on the display panel 100 while the "right" light source is lit, as shown in the center image of Figure 4; and (3) measure a third luminance distribution on the display panel 100 while both related light sources are lit, as shown in the right image of Figure 4. As described in relation to Figures 4 to 6, these three luminance distributions are used to estimate the light diffusion characteristics of the light source 210 and to generate a directional filter that represents the light diffusion characteristics of the light source 210.

[0047] The imaging device 2100 may be further configured to capture images of the display panel 100 for test patterns #1 to #4 shown in Figure 7. In some embodiments, the imaging device 2100 may be configured to (1) capture a first image of the display panel 100 while the 2D backlight system 200 illuminates the display panel 100 with test pattern #1, (2) capture a second image of the display panel 100 while the 2D backlight system 200 illuminates the display panel 100 with test pattern #2, (3) capture a third image of the display panel 100 while the 2D backlight system 200 illuminates the display panel 100 with test pattern #3, and (4) capture a fourth image of the display panel 100 while the 2D backlight system 200 illuminates the display panel 100 with test pattern #4. The images captured for test patterns #1 to #4 are used to generate demra data used for the demra function described in relation to Figures 7 to 10. Here, the Demra data includes the Demra correction coefficient for each light source 210.

[0048] In one or more embodiments, the main unit 2200 includes an interface (I / F) circuit 2210, a storage device 2220, a processor 2230, and an interface circuit 2240. In one or more embodiments, the interface circuit 2210 is configured to connect the main unit 2200 to the imaging device 2100, and the interface circuit 2240 is configured to connect the main unit 2200 to the display driver 300.

[0049] The storage device 2220 is configured as a non-temporary tangible computer-readable storage medium for storing calibration software 2250. The calibration software 2250 includes computer-executable instructions for performing adjustment or calibration processes of the display device 1000. More specifically, the calibration software 2250 may include computer-executable instructions that, at runtime, cause the processor 2230 to generate pattern generation commands that instruct the display driver 300 to illuminate the display panel 100 with desired test patterns, including the test patterns shown in Figure 4 and test patterns #1 to #4 shown in Figure 7. The pattern generation commands are provided to the display driver 300 via the interface circuit 2240.

[0050] The calibration software 2250 may also include, at runtime, computer executable instructions that cause the processor 2230 to generate control commands instructing the imaging device 2100 to capture an image of the display panel 100 while the display panel 100 is illuminated with a desired test pattern (which may include the three test patterns shown in Figure 4 or the four test patterns #1 to #4 shown in Figure 7). The control commands may be provided to the imaging device 2100 via the interface circuit 2210.

[0051] The calibration software 2250 may further include, at runtime, a computer-executable instruction that causes the processor 2230 to determine the luminance distribution of the display panel 100 for the three test patterns shown in Figure 4, based on images of the display panel 100 taken by the imaging device 2100 for those test patterns. At runtime, this computer-executable instruction further causes the processor 2230 to generate a directional filter based on the determined luminance distribution. As described above, the directional filter may represent the proportion that the target light source (sometimes called the central light source) and its surrounding light sources, which form a 3x3 light source array, each contribute to the total luminance level of the zone corresponding to the target light source. The directional filter may include directional coefficients assigned to the central light source and surrounding light sources of the 3x3 light source array.

[0052] The calibration software 2250 may further include computer-executable instructions that, at runtime, cause the processor 2230 to acquire images captured by the imaging device 2100 for test patterns #1 to #4 shown in Figure 7 via the interface circuit 2210, and to generate demra data, which may include demra correction coefficients for each light source 210, based on the captured images. The demra data may be generated using a directional filter by the process described above in relation to Figure 10. The demra data is provided to the display driver 300 via the interface circuit 2240.

[0053] The calibration software 2250 may be installed on the storage device 2220 using a non-temporary tangible computer-readable recording medium 2300 on which the calibration software 2250 is recorded. Alternatively, the calibration software 2250 may be provided to the calibration system 2000 as a computer program product that can be downloaded from a server.

[0054] In some embodiments, a non-volatile memory (NVM) 400 may be coupled to a display driver 300, and the display driver 300 may be configured to store Demra data in the NVM 400. In such embodiments, the display driver 300 may be configured to read Demra data from the NVM 400 and execute Demra functions using the read Demra data.

[0055] Figure 13 shows an example configuration of a display driver 300 configured to perform the local dimming function and demra function described above, according to one or more embodiments. In the illustrated embodiment, the display driver 300 includes an image processing circuit 310, a driver circuit 320, an image analysis circuit 330, an interface (I / F) circuit 340, a demra data memory 350, and a backlight control circuit 360.

[0056] The image processing circuit 310 is configured to perform image processing on input image data to generate processed image data. The image processing performed by the image processing circuit 310 may include color adjustment, demla correction, deburn correction, image scaling, gamma conversion, or other image processing. The driver circuit 320 receives the processed image data from the image processing circuit 310 and is configured to drive each pixel of the display panel 100 based at least partially on the processed image data.

[0057] The image analysis circuit 330 is configured to analyze input image data and generate analysis data. The analysis data may include information indicating the brightness of the input image around each light source 210. In some embodiments, the analysis data may include the average pixel level (APL) of each zone 110 (shown in Figure 3) calculated from the input image data. In other embodiments, the image analysis circuit 330 may be configured to (1) select a target image portion of the input image so as to include the zone 110 corresponding to each light source 210, (2) apply filtering to the target image portion to generate a filtered image portion for each light source 210, and (3) calculate the APL of the filtered image portion generated for each light source 210. In such embodiments, the analysis data may include the APL of the filtered image portion generated for each light source 210. The analysis data is provided to the backlight control circuit 360 and used to perform a local dimming function that individually controls the brightness levels of the light sources 210 of the 2D backlight system 200. The analysis data may also be provided to the image processing circuit 310. In such embodiments, the image processing circuit 310 may process the input image data based on the analysis data.

[0058] The interface circuit 340 is configured to receive Demra data from the calibration system 2000 and store the Demra data in the NVM 400. The interface circuit 340 is further configured to read Demra data from the NVM 400 at startup or power-on reset and store the read Demra data in the Demra data memory 350. The Demra data memory 350 is configured to provide Demra data to the backlight control circuit 360 in order to implement the Demra function.

[0059] The backlight control circuit 360 is configured to perform a local dimming function based on analysis data. More specifically, the backlight control circuit 360 is configured to generate a base backlight value for each light source 210 based on the analysis data. In some embodiments, the base backlight value for each light source 210 may be determined based on the APL of the zone 110 corresponding to that light source 210. In other embodiments, the base backlight value for each light source 210 may be determined based on the APL of the filtered image portion generated for that light source 210, as described above. The backlight control circuit 360 is further configured to receive demra data from the demra data memory 350 and to perform a demra function based on the received demra data. In one embodiment, the demra data may include a demra correction coefficient for each light source 210 of the 2D backlight system 200, and the backlight control circuit 360 may be configured to apply the demra correction coefficient for each light source 210 to the base backlight value to generate a corrected backlight value. The corrected backlight value is provided to the backlight system 200 to control the brightness level of the light source 210.

[0060] In some embodiments, the backlight control circuit 360 may include a test pattern generator 370 configured to control the brightness level of the light sources 210 of the 2D backlight system 200 in response to pattern generation commands received from a calibration system 2000 (shown in Figure 12) via an interface circuit 340. The test pattern generator 370 may be configured to generate backlight values ​​for each light source 210 in response to pattern generation commands so that the display panel 100 is illuminated with the desired test patterns. More specifically, the test pattern generator 370 may be configured to generate backlight values ​​such that the 2D backlight system 200 illuminates the display panel 100 with the test patterns when the calibration system 2000 acquires the brightness distribution on the display panel 100 for three test patterns shown in Figure 4 and generates a directional filter based on the acquired brightness distribution. Furthermore, the test pattern generator 370 may be configured to generate backlight values ​​such that the 2D backlight system 2000 illuminates the display panel 100 with test patterns #1 to #4 when the calibration system 2000 captures images of the display panel 100 for the four test patterns #1 to #4 shown in Figure 7 and generates demra data based on the captured images.

[0061] In the context describing the present invention (particularly in the context of the following claims), the use of “a,” “an,” “the,” “at least one,” and similar reference terms should be interpreted as covering both singular and plural forms unless otherwise indicated herein or unless clearly inconsistent with the context. The use of a list of one or more items following the term “at least one” (e.g., “at least one of A and B”) should be interpreted as meaning one item selected from the enumerated items (A or B), or any combination of two or more enumerated items (A and B), unless otherwise stated herein or unless clearly inconsistent with the context. The terms “equip,” “have,” “include,” and “incorporate” should be interpreted as open-ended terms (i.e., “include, but not limited to”) unless otherwise noted herein. Unless otherwise stated herein, the descriptions of value ranges are intended to serve merely as abbreviations for individually referring to each individual value that falls within the range, and each individual value is incorporated herein as if it were individually described herein. All methods described herein may be carried out in any suitable order unless otherwise indicated herein or unless it is clearly inconsistent with the context. Any examples or exemplary expressions provided herein (e.g., "like...") are intended solely to better illustrate the invention and, unless otherwise requested, do not limit the scope of the invention. Nothing in this specification should be construed as indicating that any unrequested element is essential to carrying out the invention.

[0062] Exemplary embodiments are described herein. Variations of these exemplary embodiments will become apparent to those skilled in the art by reading the foregoing description. The inventors expect that those skilled in the art will appropriately adopt such variations, and the inventors intend that the invention may be carried out in ways other than those specifically described herein. Accordingly, the invention includes all variations and equivalents of the subject matter described in the claims appended herein, as permitted by applicable law. Furthermore, any combination of the elements described above in all possible variations is incorporated herein unless otherwise specifically indicated herein or unless it is clearly inconsistent with the context.

Claims

1. Obtaining multiple brightness maps of multiple light sources in a 2D backlight system for multiple test patterns, A cumulative brightness map is generated by summing the aforementioned multiple brightness maps, Based on the cumulative brightness map, a demla correction coefficient is generated for the multiple light sources, Includes, Each test pattern indicates whether to turn on or turn off each of the multiple light sources. Each of the aforementioned multiple light sources is illuminated in only one of the multiple test patterns. The plurality of brightness maps indicate the brightness levels of the plurality of light sources for the plurality of test patterns. method.

2. The plurality of test patterns include a first test pattern in which the light sources of a first set of the plurality of light sources are turned on and the light sources of the remaining first set of the plurality of light sources are turned off. Each light source in the first set is adjacent only to the light sources in the remaining set of the first set. The method according to claim 1.

3. The aforementioned multiple test patterns further, A second test pattern in which the light sources of a second set of the aforementioned multiple light sources are turned on, A third test pattern in which the light sources of a third set of the aforementioned multiple light sources are lit, A fourth test pattern in which the light sources of the fourth set of the aforementioned plurality of light sources are lit, Includes, The light sources of the first, second, third, and fourth sets described above do not have a common light source. The method according to claim 2.

4. Each of the aforementioned plurality of light sources belongs to one of the first, second, third, and fourth sets. The method according to claim 3.

5. The first set of light sources includes a first light source, The second set of light sources includes a second light source that is horizontally adjacent to the first light source. The third set of light sources includes a third light source adjacent to the first light source in a direction perpendicular to it. The fourth set of light sources includes a fourth light source that is diagonally adjacent to the first light source, The method according to claim 3.

6. Obtaining multiple luminance maps of the multiple light sources is The process involves capturing multiple images of the display panel while the display panel is illuminated by the multiple light sources with the multiple test patterns, The process involves generating multiple brightness maps of the multiple light sources based on the multiple images, including, The method according to claim 1.

7. The method further includes generating a directional filter that represents the light diffusion characteristics of the plurality of light sources, The generation of the Demura correction coefficient for the aforementioned multiple light sources is further based on the directional filter. The method according to claim 1.

8. To generate the aforementioned directional filter, The first luminance distribution is obtained for a fifth test pattern in which two adjacent light sources among the aforementioned plurality of light sources are lit, The second luminance distribution is obtained for the sixth test pattern in which one of the two adjacent light sources is lit, The third luminance distribution is obtained for the seventh test pattern in which the other of the two adjacent light sources is lit, The directional filter is generated based on the first, second, and third luminance distributions, including, The method according to claim 7.

9. To generate the Demura correction coefficient for the aforementioned multiple light sources, Applying the aforementioned Demla correction coefficient and the aforementioned directional filter to the cumulative luminance map generates a corrected luminance map, The demla correction coefficient is modified based on the corrected luminance map, including, The method according to claim 7.

10. Processor and During execution, the processor will For multiple test patterns, multiple brightness maps of multiple light sources in a 2D backlight system are obtained. A cumulative luminance map is generated by summing the aforementioned multiple luminance maps. A storage device configured to store computer executable instructions for generating demura correction coefficients for the plurality of light sources based on the cumulative luminance map, Equipped with, Each test pattern indicates whether to turn on or turn off each of the multiple light sources. Each of the aforementioned multiple light sources is illuminated in only one of the multiple test patterns. The plurality of brightness maps indicate the brightness levels of the plurality of light sources for the plurality of test patterns. Calibration system.

11. The plurality of test patterns include a first test pattern in which the light sources of a first set of the plurality of light sources are turned on and the light sources of the remaining first set of the plurality of light sources are turned off. Each light source in the first set is adjacent only to the light sources in the remaining set of the first set. The calibration system according to claim 10.

12. The aforementioned multiple test patterns further, A second test pattern in which the light sources of a second set of the aforementioned multiple light sources are turned on, A third test pattern in which the light sources of a third set of the aforementioned multiple light sources are lit, A fourth test pattern in which the light sources of the fourth set of the aforementioned plurality of light sources are lit, Includes, The light sources of the first, second, third, and fourth sets described above do not have a common light source. The calibration system according to claim 11.

13. The first set of light sources includes a first light source, The second set of light sources includes a second light source that is horizontally adjacent to the first light source. The third set of light sources includes a third light source adjacent to the first light source in a direction perpendicular to it. The fourth set of light sources includes a fourth light source that is diagonally adjacent to the first light source, The calibration system according to claim 12.

14. The imaging device further comprises an imaging device configured to capture multiple images of the display panel while the display panel is illuminated by the multiple light sources with the multiple test patterns, Obtaining the plurality of brightness maps of the plurality of light sources includes generating the plurality of brightness maps of the plurality of light sources based on the plurality of images. The calibration system according to claim 10.

15. The aforementioned computer executable instruction causes the processor to generate a directional filter representing the light diffusion characteristics of the multiple light sources during execution. The generation of the Demura correction coefficient for the aforementioned multiple light sources is further based on the directional filter. The calibration system according to claim 10.

16. At runtime, the processor, For multiple test patterns, multiple brightness maps of multiple light sources in a 2D backlight system are obtained. A cumulative luminance map is generated by summing the aforementioned multiple luminance maps. The system stores a computer executable instruction that generates a demla correction coefficient for the multiple light sources based on the cumulative luminance map. Each test pattern indicates whether to turn on or turn off each of the multiple light sources. Each of the aforementioned multiple light sources is illuminated in only one of the multiple test patterns. The plurality of brightness maps indicate the brightness levels of the plurality of light sources for the plurality of test patterns. Non-temporary tangible computer-readable storage medium.

17. The plurality of test patterns include a first test pattern in which the light sources of a first set of the plurality of light sources are turned on and the light sources of the remaining first set of the plurality of light sources are turned off. Each light source in the first set is adjacent only to the light sources in the remaining set of the first set. The non-temporary tangible computer-readable storage medium according to claim 16.

18. The aforementioned multiple test patterns further, A second test pattern in which the light sources of a second set of the aforementioned multiple light sources are turned on, A third test pattern in which the light sources of a third set of the aforementioned multiple light sources are lit, A fourth test pattern in which the light sources of the fourth set of the aforementioned plurality of light sources are lit, Includes, The light sources of the first, second, third, and fourth sets described above do not have a common light source. The method described in claim 17.

19. The first set of light sources includes a first light source, The second set of light sources includes a second light source that is horizontally adjacent to the first light source. The third set of light sources includes a third light source adjacent to the first light source in a direction perpendicular to it. The fourth set of light sources includes a fourth light source that is diagonally adjacent to the first light source, The non-temporary tangible computer-readable storage medium according to claim 18.

20. The aforementioned computer executable instruction causes the processor to generate a directional filter representing the light diffusion characteristics of the multiple light sources during execution. The generation of the Demura correction coefficient for the aforementioned multiple light sources is further based on the directional filter. The non-temporary tangible computer-readable storage medium according to claim 16.

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