Adjustment of local dimming function

Abstract

A method for adjusting a local dimming function includes measuring a first luminance level of a measurement region of a display panel while illuminating the display panel with four light sources of a backlight device, the four light sources being arranged in two rows and two columns. The method further includes measuring a second luminance level of the measurement region while illuminating the display panel with two of the four light sources, the two of the four light sources being arranged in a same row or a same column. The method further includes measuring a third luminance level of the measurement region while illuminating the display panel with one of the four light sources. The method further includes determining a filter coefficient of a directional filter for a local dimming function based on the first, second, and third luminance levels of the measurement region.

Description

Technical Field

[0001] The present disclosure relates generally to panel display devices, and more particularly to adjustment of local dimming functions implemented in panel display devices. Background Art

[0002] The local dimming function is one of the technologies for increasing the contrast of a liquid crystal display (LCD) device. The local dimming technology can achieve high dynamic contrast and low power consumption by individually controlling the corresponding light sources (e.g., light emitting diodes (LEDs)) of the backlight system according to input image data. In one implementation, the brightness level of each light source can be controlled based on the luminance of the portion of the input image displayed in the area of ​​the LCD panel illuminated by the light source.

[0003] The image quality of an LCD device with a local dimming function may depend on the light directivity characteristics (or light distribution characteristics) of the light source of the backlight system. In order to reduce display artifacts such as halo, flicker, and brightness unevenness, the local dimming function is expected to be adjusted based on the light directivity characteristics of the light source. Summary of the invention

[0004] This summary is provided to introduce a selection of concepts that are further described below in a simplified form. This summary is not intended to necessarily identify key features or essential features of the present disclosure. The present disclosure may include the following various aspects and embodiments.

[0005] In an exemplary embodiment, the present disclosure provides a method. The method includes measuring a first luminance level of a measurement area of ​​a display panel when the display panel is illuminated by four light sources of a backlight device, and the four light sources are arranged in two rows and two columns. The method further includes measuring a second luminance level of the measurement area when the display panel is illuminated by two of the four light sources, and the two of the four light sources are arranged in the same row or the same column. The method further includes measuring a third luminance level of the measurement area when the display panel is illuminated by one of the four light sources. The method further includes determining a filter coefficient of a directional filter for a local dimming function implemented in a display device including the display panel based on the first luminance level, the second luminance level, and the third luminance level of the measurement area.

[0006] Further features and aspects are described in additional detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 An example configuration of a display device according to one or more embodiments is shown.

[0008] Figure 2 According to one or more embodiments Figure 1An example side view configuration of a display device shown in .

[0009] Figure 3 An example arrangement of light sources of a backlight device according to one or more embodiments is shown.

[0010] Figure 4 An example configuration of a display driver according to one or more embodiments is shown.

[0011] Figure 5 is a flow diagram illustrating an example process for generating analytical data in accordance with one or more embodiments.

[0012] Figure 6 An example selection of a target portion of an input image of a light source of interest is shown in accordance with one or more embodiments.

[0013] Figure 7 is a three-dimensional (3D) graph showing example filter coefficients defined for pixels of a target portion selected for a light source of interest.

[0014] Figure 8 An overview of image processing performed in an image analysis circuit according to one or more embodiments is shown.

[0015] Fig.9A Example test patterns are shown in accordance with one or more embodiments.

[0016] Fig. 9B An example arrangement of measurement zones is shown in accordance with one or more embodiments.

[0017] Fig.10 An example process for adjusting a directional filter in accordance with one or more embodiments is shown.

[0018] Fig.11 is a diagram explaining technical meanings of vertical / horizontal (V / H) parameters and diagonal (D) parameters according to one or more embodiments.

[0019] Fig.12 is a diagram illustrating example filter coefficients for a directional filter according to one or more embodiments.

[0020] Fig.13 is an illustration according to one or more embodiments Fig.12 3D plot of example filter coefficients for a directional filter.

[0021] Fig.14 An example configuration of a display driver according to one or more embodiments is shown.

[0022] To facilitate understanding, the same reference numerals have been used, where possible, to designate elements common to the accompanying drawings. It is contemplated that elements disclosed in one embodiment may be utilized in other embodiments without specific statements. Suffixes may be attached to the reference numerals to distinguish elements from each other. Unless specifically stated, the drawings referenced herein should not be understood to be drawn to scale. In addition, for clarity of representation and explanation, the drawings are generally simplified and details or components are omitted. The drawings and discussion are used to explain the principles discussed below. DETAILED DESCRIPTION

[0023] The following detailed description is exemplary in nature and is not intended to limit the disclosure or the application and use of the disclosure. In addition, it is not intended to be bound by any express or implied theory presented in the foregoing background technology, summary of the invention and the accompanying drawings or the following detailed description.

[0024] In the following detailed description, many specific details are set forth in order to provide a more thorough understanding of the disclosed technology. However, it will be apparent to one of ordinary skill in the art that the disclosed technology can be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0025] As used herein, the term "coupled" means directly connected to or connected through one or more intermediate components or circuits. In addition, throughout this application, ordinal numbers (e.g., first, second, third, etc.) can be used as adjectives of elements (i.e., any noun in this application). The use of ordinal numbers is not intended to imply or create any particular ordering of elements, nor is it intended to limit any element to only a single element, unless (such as by using the terms "before", "after", "single" and other such terms) is clearly disclosed. On the contrary, the use of ordinal numbers is to distinguish between elements. As an example, a first element is different from a second element, and a first element may include more than one element and be after (or before) a second element in the ordering of elements.

[0026] The local dimming function is one of the technologies for improving the image quality of a liquid crystal display (LCD) device, which can achieve high dynamic contrast and low power consumption by individually controlling the corresponding light sources (e.g., light emitting diodes (LEDs)) of a backlight system. In one implementation, the brightness level of each light source can be controlled based on the brightness of the portion of the input image displayed in the area of ​​the LCD panel illuminated by the light source.

[0027] The image quality of an LCD device with a local dimming function may depend on the light directivity characteristics (or light distribution characteristics) of a light source of a backlight system. In order to mitigate display artifacts such as halo, flicker, and brightness non-uniformity, the local dimming function is adjusted based on the light directivity characteristics of the light source.

[0028] In some implementations, the local dimming function may use a directional filter prepared based on the light directionality characteristics to determine the brightness level of the corresponding light source of the backlight system. The directional filter may be applied to a portion of the input image corresponding to each light source to generate a filtered image portion, and the brightness level of each light source may be controlled based on the average picture level (APL) of the filtered image portion. The use of the directional filter enables the local dimming function to be performed based on the light directionality characteristics of the light source. In order to improve the image quality, the directional filter may be appropriately adjusted. The present disclosure provides various techniques for efficiently adjusting the directional filter to achieve improved image quality using the local dimming function.

[0029] Figure 1 An example configuration of a display device 1000 according to one or more embodiments is shown. In the illustrated embodiment, the display device 1000 includes a display panel 100, a backlight device 200, and a display driver 300. The display panel 100 may be a light-transmitting display panel, such as an LCD panel. The backlight device 200 is configured to illuminate the display panel 100. The display driver 300 is configured to receive input image data and drive the display panel 100 based on the input image data. The input image data may correspond to an input image and include pixel data of pixels of the input image. In one implementation, the pixel data of each pixel includes the grayscale of the corresponding primary color (e.g., red (R), green (G), and blue (B)). In one implementation, each pixel of the display panel 100 may include R, G, and B sub-pixels configured to display red, green, and blue, respectively, and the pixel data of each pixel of the input image may include R, G, and B grayscales that specify the luminance level of the R, G, and B sub-pixels, respectively.

[0030] The backlight device 200 includes an array of light sources 210. It should be noted that since the light sources 210 are arranged as shown in the side view of the display device 1000, Figure 2 As shown in FIG. 2 , the light source 210 is located behind the display panel 200, so the light source 210 is in the form of a phantom. Figure 1 Although Figure 1 64 light sources 210 are shown in the backlight 200, but those skilled in the art will appreciate that the backlight 200 may include more or less than 64 light sources 210. In actual implementations, the backlight 200 may include hundreds to thousands of light sources 210. In one implementation, each light source 210 may include one or more light emitting diodes (LEDs) or different types of light sources.

[0031] Figure 3An example arrangement of the light sources 210 of the backlight device 200 according to one or more embodiments is shown. In the illustrated embodiment, the display panel 100 is divided into square areas 110 arranged in rows and columns, and the light sources 210 are respectively located behind the corresponding areas 110. Each light source 210 is located so that the projection of each light source 210 onto the display panel 100 is positioned at the center (e.g., the geometric center) of one of the corresponding areas 110. As used herein, the "corresponding area" 110 of the light source 210 refers to the area 110 including the projection of the light source 210 onto the display panel 100. It should be noted that due to the light distribution characteristics of the light source 210, each light source 210 mainly illuminates the corresponding area 110, but may secondarily illuminate at least a portion of the area 110 surrounding (e.g., adjacent to) the corresponding area 110.

[0032] Figure 4 An example configuration of a display driver 300 according to one or more embodiments is shown. In the illustrated embodiment, the display driver 300 includes an image processing circuit 310, a driver circuit 320, an image analysis circuit 330, and a backlight control circuit 340. The image processing circuit 310 is configured to perform image processing in the input image data to generate processed image data. The image processing performed by the image processing circuit 310 may include color adjustment, demura correction, deburn correction, image scaling, gamma conversion, or other image processing. The driver circuit 320 is configured to receive the processed image data from the image processing circuit 310 and drive the corresponding pixels of the display panel 100 based at least in part on the processed image data. The image analysis circuit 330 is configured to analyze the input image data to generate analysis data. The analysis data may include information indicating the brightness of the input image around each light source 210. The details of the generation of the analysis data will be described later. The analysis data is provided to the backlight control circuit 340. The backlight control circuit 340 is configured to implement a local dimming function based on the analysis data. More specifically, the backlight control circuit 340 is configured to generate backlight values ​​for the corresponding light sources 210 based on the analysis data to individually control the light sources 210. The backlight values ​​of the light sources 210 may indicate the brightness level to which the light sources 210 are to be controlled. The analysis data may be further provided to the image processing circuit 310. In such implementations, the image processing circuit 310 may process the input image data based on the analysis data.

[0033] Figure 5 is a flow chart illustrating an example process 500 for generating analysis data according to one or more embodiments. In one implementation, the process 500 is implemented by the image analysis circuit 330. It will be appreciated that any of the following steps may be performed in any suitable order.

[0034] In step 502 , the image analysis circuit 330 selects a target portion of the input image for each light source 210 . Figure 6 2 shows an example selection of a target portion of an input image of a light source of interest 210 according to one or more embodiments. Figure 6 , reference numeral "110a" denotes a region 110 corresponding to the light source of interest 210, and reference numeral "110b" denotes eight regions 110 adjacent to the region 110a. The region 110a corresponding to the light source of interest 210 is indicated by shading in FIG. Figure 6 In addition, reference numeral "120a" represents the projection of the light source of interest 210 onto the display panel 100, i.e., the center (e.g., geometric center) of the zone 110a, and reference numeral "120b" represents the projection of the light source 210 surrounding the light source of interest 210 onto the display panel 100, i.e., the center (e.g., geometric center) of the zone 110b surrounding the zone 110a.

[0035] In one or more embodiments, a target portion of an input image for a light source 210 of interest is selected so that the target portion is displayed in a corresponding area 130a of the display panel 100, wherein the corresponding area 130a is a substantially square area having a boundary passing through the centers of eight zones 110b surrounding the zone 110a corresponding to the light source 210 of interest. Four of the eight surrounding zones 110b have centers at the four corners of the corresponding area 130a, and the centers of the other four adjacent zones 110b are on the four sides of the corresponding area 130a. Target portions of input images for other light sources 210 may be selected in a similar manner. The target portion of each light source 210 may be selected differently, as long as the area of ​​the display panel 100 in which the target portion selected for each light source 210 is displayed includes at least the zone 110 corresponding to the light source 210. It should be noted that the target portions of the input image selected for adjacent light sources 210 may overlap. Figure 6 In the example shown in , the height and width of each target portion are both twice the height and width of zone 110, and the target portions selected for light sources 210 corresponding to zone 110a partially overlap with the target portions selected for light sources 210 corresponding to zone 110b.

[0036] Back to reference Figure 5In step 504, the image analysis circuit 330 applies a directional filter to the target portion of the input image selected for each light source 210 to generate a filtered image portion for each light source 210. In one or more embodiments, the directional filter includes filter coefficients defined for corresponding pixels of the target portion of the input image, and the filtered image portion is generated by applying the filter coefficients to the pixel data of the corresponding pixels of the target portion. In one implementation, the pixel data of the corresponding pixels of the filtered image portion can be generated by multiplying the pixel data of the corresponding pixels of the target portion by the filter coefficients defined for the corresponding pixels of the target portion.

[0037] Figure 7 1 is a three-dimensional (3D) diagram showing example filter coefficients defined for pixels of a target portion selected for a light source of interest 210 corresponding to region 110a. Reference numeral "140a" denotes the target portion selected for light source of interest 210. Note that the outer boundary of the target portion 140a selected for light source of interest 210 is the same as that for pixels in region 110a. Figure 6 The boundaries of the corresponding area 130a defined by the light source 210 shown in FIG. 2 coincide with each other.

[0038] In the example shown, the filter coefficients defined for the pixels of the target portion 140a increase as the corresponding distance between the pixels of the target portion 140a of the input image and the center of the zone 110a (i.e., the projection of the light source 210 of interest onto the display panel 100) decreases. More specifically, the filter coefficient for the pixel located at the center of the zone 110a is Wmax (e.g., 100% or 1.0), which is the maximum filter coefficient, and the filter coefficient for the pixel located at the boundary of the target portion 140a is zero. The filter coefficients defined for the other pixels of the target portion 140a are values ​​between zero and Wmax. The filter coefficients thus defined are applied to the pixel data of the corresponding pixels of the target portion 140 to generate a filtered image portion. The filter coefficients for the pixels of other target portions of other light sources 210 can be defined in a similar manner.

[0039] Back to reference Figure 5 In step 506, the image analysis circuit 330 analyzes the filtered image portion generated for each light source 210 to generate analysis data. In one implementation, the analysis data may include an average picture level (APL) of the filtered image portion generated for the corresponding light source 210. The APL of the filtered image portion is the average of the pixel luminance levels of the filtered image portion. In implementations in which the analysis data includes the APL of the filtered image portion, the backlight control circuit 340 may be configured to determine a backlight value for the corresponding light source 210 based on the APL of the filtered image portion generated for the corresponding light source 210.

[0040] Figure 8 1 shows an overview of image processing performed in the image analysis circuit 330 according to one or more embodiments. The image analysis circuit 330 is configured to first select a target portion of the input image for each light source 210. As discussed above, the target portion of the input image for each light source 210 is selected so that the target portion is displayed in the corresponding area 130a of the display panel 100, as described with respect to FIG. Figure 6 The image analysis circuit 330 is further configured to apply a directional filter to a target portion selected for each light source 210 to generate a filtered image portion. The image analysis circuit 330 is further configured to generate analysis data based on the filtered image portion generated for the corresponding light source 210. In one implementation, the analysis data includes an APL of the filtered image portion generated for the corresponding light source 210. The APL of the filtered image portion can be used to determine the backlight value of the corresponding light source 210.

[0041] The present disclosure recognizes that in order to achieve improved image quality based on local dimming functionality, it would be advantageous for the directional filter to be appropriately adjusted. Adjustment of the directional filter may be performed during an adjustment or calibration process of the display device. Alternatively, the directional filter may be adjusted during normal use of the display device. In various embodiments, the directional filter may be adjusted based on measurements of optical properties of the light source of the backlight device. For example, the luminance distribution on the display panel may be measured using various test modes (or evaluation modes) of the light source to evaluate the light directional properties of the light source, and the directional filter may be adjusted based on the measured luminance distribution.

[0042] One method of accurately evaluating the light directional characteristics of a light source may be to use an increased number of test patterns to measure the optical characteristics of the light source. However, using an increased number of test patterns may increase the turnaround time (TAT) for adjustment of the directional filter. Therefore, in some embodiments, the directional filter may be appropriately adjusted using a reduced number of test patterns. The following is a detailed description of an embodiment of appropriately adjusting the directional filter using a reduced number of test patterns to achieve improved image quality.

[0043] In one or more embodiments, the directional filter may be based on the use of Fig.9A The light source is adjusted based on the measurements of the test modes #1, #2, and #3 shown in FIG. Test mode #1 is a mode in which one of the light sources is "turned on." The term "turned on" may mean that the light source is driven to emit light at a predetermined brightness level (e.g., a maximum allowed brightness level). Test mode #2 is a mode in which two light sources in a row or column are turned on. Note that Fig.9A2 is shown where two light sources in a row are turned on. Test pattern #3 is a pattern where all four light sources are turned on. These test patterns are consistent with four light sources arranged in two rows and two columns (e.g., Figures 1 to 3 The adjustment process involves illuminating the display panel 100 with test patterns #1, #2, and #3, respectively, and measuring the luminance levels of the measurement areas of the test patterns #1, #2, and #3, respectively.

[0044] Fig. 9B An example arrangement of a measurement zone, denoted by reference numeral 900, is shown according to one or more embodiments. The measurement zone 900 is defined to surround four zones 110 corresponding to four light sources 210 associated with adjustment of a directional filter. It should be noted that the projections of the four light sources 210 onto the display panel 100 are located at the centers of the four zones 110. In the illustrated embodiment, the measurement zone 900 is defined to have a circular shape surrounding the four zones 110. In order to evaluate the light directivity characteristics of the light source 210, the measurement zone 900 is defined to be as small as possible while surrounding the four zones 110, so that part of the light emitted from the light source 210 leaks out of the measurement zone 900. In some embodiments, the measurement zone 900 is defined so that the boundary of the measurement zone 900 just circumscribes the four zones 110.

[0045] Fig.10 An example process 1000 for adjusting a directional filter according to one or more embodiments is shown. It will be appreciated that any of the following steps may be performed in any suitable order, except that the order shown therein is necessary as will be apparent to one skilled in the art. In step 1002, one of the four light sources 210 associated with the adjustment is turned on to illuminate the display panel using test pattern #1. This is followed by measuring the luminance level in measurement area 900 when the display panel is illuminated using test pattern #1 in step 1004. The luminance level measured in step 1004 is referred to as luminance level L. 1LS .

[0046] In step 1006, two light sources 210 in a row (or column) are turned on to illuminate the display panel using test pattern #2. This is followed by measuring the luminance level in measurement area 900 when the display panel is illuminated using test pattern #2 in step 1008. The luminance level measured in step 1008 is referred to as luminance level L. 2LS .

[0047] In step 1010, all of the four light sources 210 associated with the adjustment are turned on to illuminate the display panel using test pattern #3. This is followed by measuring the luminance level in the measurement area 900 when the display panel is illuminated using test pattern #3 in step 1012. The luminance level measured in step 1012 is referred to as luminance level L. 4LS .

[0048] In step 1014, the vertical / horizontal (V / H) parameters are based on the luminance level L measured in step 1004. 1LS and the luminance level L measured in step 1008 2LS The V / H parameter indicates the light directivity characteristics (or light distribution characteristics) of the light source 210 in the vertical and horizontal directions. In one or more embodiments, the V / H parameter is calculated according to the following expression (1):

[0049] In step 1016, the diagonal (D) parameter is based on the luminance level L measured in step 1004. 1LS and the luminance level L measured in step 1012 4LS The D parameter indicates the light directivity characteristic (or light distribution characteristic) of the light source 210 in the diagonal direction. In one or more embodiments, the D parameter is calculated according to the following expression (2):

[0050] Fig.11 is a diagram explaining the technical meaning of the V / H and D parameters calculated by expressions (1) and (2) according to one or more embodiments. Fig.11 1 is shown in four images displayed in four zones arranged in two rows and two columns. The leftmost image contains an object 1102 located at the center of the upper right zone, and the second image from the left contains an object 1104 located at the boundary between the upper left zone and the upper right zone. The second image from the right contains an object 1106 located at the boundary between the upper right zone and the lower right zone, and the rightmost image contains an object 1108 located at a common corner of the four zones.

[0051] In one or more embodiments, the V / H and D parameters calculated according to expressions (1) and (2) are such that the luminance levels listed below are substantially the same: (a) The luminance of object 1102 for the case when one light source illuminates the upper right region with a luminance level of 100%. (b) The luminance of object 1102 for the case when two light sources illuminate the upper right region with luminance levels equal to the V / H parameter (e.g. Fig.11 52% of the luminance of object 1104 when illuminating the area in the upper row). (c) When two light sources use luminance levels equal to the V / H parameter (e.g. Fig.11 52% of the luminance of object 1106 when the area in the right column is illuminated. (d) When four light sources are illuminated with luminance levels equal to the D parameter (e.g. Fig.11 The luminance of object 1108 when four zones are illuminated (27% of the luminance). The light directivity characteristics (or light distribution characteristics) of the light source are well expressed by the V / H and D parameters calculated in this way.

[0052] Back to reference Fig.10 , in step 1018, filter coefficients of the directional filter are determined based on the V / H parameter and the D parameter thus calculated. Fig.12 is a diagram showing example filter coefficients for a directional filter according to one or more embodiments, and Fig.13 is an illustrative diagram showing example filter coefficients in the form of a 3D graph. Fig.12 and 13 , reference numeral 110a denotes a zone 110 corresponding to a light source 210 of interest, and reference numeral 110b denotes eight zones 110 surrounding zone 110a. Reference numeral 120a denotes the center of zone 110a, and reference numeral 120b denotes the corresponding center surrounding zone 110b. Note that the projection of each light source 210 onto the display panel 100 is positioned at the center of the zone 110 corresponding to the light source 210. Reference numeral 140a denotes a target portion of the input image selected for the light source 210 of interest.

[0053] refer to Fig.12 In one or more embodiments, the filter coefficient of the pixel located at the center 120a of the area 110a corresponding to the light source of interest 210 is determined to be the maximum filter coefficient Wmax, which can be 1.0 or 100%. At the same time, the filter coefficient of the pixel located at the boundary of the target portion 140a selected for the light source of interest 210 is determined to be 0% or zero.

[0054] The filter coefficients for pixels located at the midpoint 150a of the horizontal side of the region 110a corresponding to the light source of interest 210 are determined based on the V / H parameter. In one implementation, the filter coefficients for pixels located at the midpoint 150a are determined to be equal to the V / H parameter. Fig.11 In the example shown in , the filter coefficient for the pixel at the midpoint 150a is 52% or 0.52.

[0055] The filter coefficient for a pixel located at the midpoint 160a of the vertical side of the region 110a corresponding to the light source of interest 210 is determined based on the V / H parameter. In one implementation, the filter coefficient for a pixel located at the midpoint 160a is determined to be equal to the V / H parameter. Fig.11 In the example shown in , the filter coefficient for the pixel at the midpoint 160a is 52% or 0.52.

[0056] The filter coefficients for pixels located at corner 170a of region 110a corresponding to light source of interest 210 are determined based on the D parameter. In one implementation, the filter coefficients for pixels located at corner 170a are determined to be equal to the D parameter. Fig.11 In the example shown in , the filter coefficient for the pixel located at corner 170a is 27% or 0.27.

[0057] The filter coefficients for the other pixels of the target portion 140a selected for the light source of interest 210 are determined by interpolating the pixel filter coefficients determined as described above. In one implementation, the filter coefficients for the other pixels of the target portion 140a are determined according to Fig.13 The 3D diagram shown in is determined.

[0058] It should be noted that the above adjustment process described with respect to Figures 9 to 13 uses only three test patterns (test patterns #1, #2 and #3) to adjust the directional filter. The adjustment process of the present disclosure enables a reduction in the TAT of adjustment of the directional filter.

[0059] In one or more embodiments, the filter coefficients for the directional filter generated by the adjustment process may be stored in the display driver 300. In other embodiments, the V / H and D parameters generated as described above may be stored in the display driver 300, and the display driver 300 may be configured to generate the filter coefficients for the directional filter based on the stored V / H and D parameters. Of course, it will be appreciated that the filter coefficients or the V / H and D parameters may be stored outside the display driver in a separate memory.

[0060] In one or more embodiments, the display driver may be configured to control the light source 210 of the backlight device 200 to illuminate the display panel 100 using the test patterns #1, #2, and #3 during adjustment of the directional filter. Fig.14 FIG. 1 shows an example configuration of a display driver 1300 configured thus according to one or more embodiments. In the illustrated embodiment, the display driver 1300 is similarly configured as Figure 4The display driver 300 shown in FIG. 1 includes a test pattern generator 350 in addition to the backlight control circuit 340. During adjustment of the directional filter, the test pattern generator 350 generates backlight values ​​for the corresponding light sources 210 so that the display panel 100 is illuminated using test patterns #1, #2, and #3. The test pattern generator 350 may be configured to generate the backlight values ​​in response to a command received from an external controller.

[0061] The use of the terms "a", "an", "the", "at least one", and similar indicators in the context of describing the present invention (especially in the context of the following claims) is to be interpreted as covering both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context. The use of the term "at least one" followed by a listing of one or more items (e.g., "at least one of A and B") is to be interpreted as meaning one item (A or B) selected from the listed items or any combination of two or more items (A and B) of the listed items, unless otherwise indicated herein or clearly contradicted by the context. Unless otherwise stated, the terms "comprising", "including", "having", "comprising" are to be interpreted as open-ended terms (i.e., meaning "including but not limited to"). Unless otherwise indicated herein, the listing of ranges of values ​​herein is intended merely to be used as a shorthand method of individually referring to each individual value falling within the range, and each individual value is incorporated into the specification as if it were individually recited herein. Unless otherwise indicated herein or otherwise clearly contradicted with the context, all methods described herein can be performed in any suitable order. Unless otherwise claimed, the use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the present invention and does not limit the scope of the present invention. Any language in the specification should not be interpreted as indicating any unclaimed element as essential to the practice of the present invention.

[0062] Exemplary embodiments are described herein. After reading the foregoing description, variations of those exemplary embodiments may become apparent to those of ordinary skill in the art. The inventors expect that those skilled in the art will adopt such variations where appropriate, and the inventors intend to practice the invention in a manner different from that specifically described herein. Accordingly, the present invention includes all modifications and equivalents of the subject matter recited in the claims appended thereto, as permitted by applicable law. In addition, unless otherwise indicated herein or otherwise explicitly contradicted with the context, any combination of the above-described originals in all their possible variations is encompassed by the present invention.

Claims

1. A method comprising: measuring a first luminance level of a measurement area of ​​the display panel while illuminating the display panel using four light sources of a backlight device, the four light sources being arranged in two rows and two columns; measuring a second luminance level of the measurement area when illuminating the display panel with two of the four light sources, the two of the four light sources being arranged in the same row or the same column; When illuminating the display panel with one of the four light sources, measuring a third luminance level of the measurement area; as well as Based on the first, second, and third luminance levels of the measurement area, filter coefficients of a directional filter for a local dimming function implemented in a display device including the display panel are determined.

Images