Backlight control of display device

Abstract

A display device includes a backlight device and a backlight control circuit. The backlight device includes a plurality of light sources configured to illuminate the display panel. The backlight control circuit is configured to apply a filter to a target portion of an input image to generate a filtered image portion. A target portion of the input image is displayed in a corresponding area of the display panel illuminated by a target light source of the plurality of light sources. The backlight control circuit is further configured to control a brightness level of the target light source based on a maximum pixel brightness level of the filtered image portion and a local average image level (APL) of the filtered image portion.

Description

[0001] Cross-references to related applications This application is a continuation-in-part of U.S. patent application serial number 18 / 473,675 filed on September 25, 2023, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] The present disclosure relates generally to panel display devices, and more particularly to backlight control of display devices. Background Art

[0003] A display device having a light-transmitting display panel (such as a light-transmitting liquid crystal display (LCD) panel) includes a backlight that illuminates the light-transmitting display panel. Modern backlighting systems (e.g., direct-type backlighting, full-array backlighting, etc.) can illuminate the display panel with an array of light sources (e.g., light-emitting diodes (LEDs)) located behind the display panel. The light source can be configured to illuminate corresponding areas of the display panel. The use of a light source array for backlighting promotes local dimming, which provides brighter and / or darker parts of the displayed image to enhance image quality. Summary of the invention

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

[0005] In an exemplary embodiment, the present disclosure provides a display device, which includes a backlight device and a backlight control circuit. The backlight device includes a plurality of light sources configured to illuminate a display panel. The backlight control circuit is configured to apply a filter to a target portion of an input image to generate a filtered image portion. The target portion of the input image is displayed in a corresponding area of ​​the display panel illuminated by a target light source among the plurality of light sources. The backlight control circuit is also configured to control the brightness level of the target light source based on a maximum pixel brightness level of the filtered image portion and a local average picture level (APL) of the filtered image portion.

[0006] In another exemplary embodiment, the present disclosure provides a display driver including a backlight control circuit coupled to a backlight device, the backlight device including a plurality of light sources that illuminate a display panel. The backlight control circuit is configured to apply a filter to a target portion of an input image to generate a filtered image portion. The target portion of the input image is displayed in a corresponding area of ​​the display panel illuminated by a target light source among the plurality of light sources. The backlight control circuit is further configured to control a brightness level of the target light source based on a maximum pixel brightness level of the filtered image portion and a local APL of the filtered image portion.

[0007] In yet another exemplary embodiment, the present disclosure provides a method. The method includes illuminating a display panel with a plurality of light sources of a backlight device. The method further includes applying a filter to a target portion of an input image to generate a filtered image portion. The target portion of the input image is displayed in a corresponding area of ​​the display panel illuminated by a target light source among the plurality of light sources. The method also includes controlling a brightness level of the target light source based on a maximum pixel brightness level of the filtered image portion and a local APL of the filtered image portion.

[0008] Further features and aspects are described in more detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1A Examples of bright foreground objects having the same specified brightness level but different sizes displayed on a dark background are shown in accordance with one or more examples of the present disclosure.

[0010] Figure 1B An example is shown in which a foreground object having a maximum brightness level moves between adjacent areas in a dark background having a minimum brightness level according to one or more examples of the present disclosure.

[0011] Figure 2 An example configuration of a display device according to one or more embodiments is shown.

[0012] Figure 3 is a diagram showing a method according to one or more embodiments Figure 2 A side view of an example configuration of a display device.

[0013] Figure 4 Example arrangements of light sources are shown in accordance with one or more embodiments.

[0014] Figure 5 An example configuration of a display driver according to one or more embodiments is shown.

[0015] Figure 6 An example configuration of a backlight control circuit according to one or more embodiments is shown.

[0016] Fig. 7A An example selection of a target portion of an input image for a light source is shown in accordance with one or more embodiments.

[0017] Figure 7B Examples of filter coefficients defined for pixels of a target portion selected for a light source are shown in accordance with one or more embodiments.

[0018] Figure 8 An overview of image processing performed in an image filtering and analysis circuit is shown in accordance with one or more embodiments.

[0019] Fig. 9A Example mitigation of flicker in accordance with one or more embodiments is shown.

[0020] Fig. 9B is a partial view of a display device showing an example arrangement of regions and corresponding light sources according to one or more embodiments.

[0021] Fig.10 An example relationship between a filtered image local APL and a weight assigned to a maximum pixel brightness level of a target portion is shown in accordance with one or more embodiments.

[0022] Fig.11 An example relationship between a modified local APL and a base brightness level is shown in accordance with one or more embodiments.

[0023] Fig.12 An example relationship between a filtered image local APL and a lifting factor is shown in accordance with one or more embodiments.

[0024] Fig.13A Example operations for displaying a bright foreground object on a dark background are illustrated in accordance with one or more embodiments.

[0025] Fig. 13B Example operations for displaying a grayscale image are shown in accordance with one or more embodiments.

[0026] Fig.14A An example image is shown for which a “boost” function is advantageous in accordance with one or more embodiments.

[0027] Fig. 14B An example image is shown for which a “boost” function is disabled in accordance with one or more embodiments.

[0028] Fig.15 An example configuration of a backlight control circuit according to other embodiments is shown.

[0029] Fig.16 An example relationship between a global APL and a boost factor is shown in accordance with one or more embodiments.

[0030] Fig.17 is an example configuration of a backlight control circuit according to yet some other embodiments.

[0031] Fig.18A An example relationship between ambient light brightness level and display brightness value (DBV) is shown in accordance with one or more embodiments.

[0032] Fig.18BAnother example relationship between ambient light brightness level and DBV is shown in accordance with one or more embodiments.

[0033] Fig.19 An example of controlling a DBV in response to an environment in which a panel display device is used according to one or more embodiments is shown.

[0034] Fig. 20 Example configurations of backlight control circuits according to further embodiments are shown.

[0035] Fig.21 An example relationship between DBV and compensation ratio is shown according to one or more embodiments.

[0036] Fig.22A An example of a relationship between a compensation weight of a maximum pixel brightness level and a filtered image local APL when a panel display device is used in a bright environment according to one or more embodiments is shown.

[0037] Fig. 22B An example of a relationship between a compensation weight of a maximum pixel brightness level and a filtered image local APL when a panel display device is used in a dark environment according to one or more embodiments is shown.

[0038] Fig.23 is a flow chart of an exemplary process for controlling a light source of a backlight device according to one or more embodiments.

[0039] For ease of understanding, the same reference numerals have been used, where possible, to represent elements common to the drawings. It is conceivable that an element disclosed in one embodiment may be used in other embodiments without specific description. Suffixes may be attached to the reference numerals to distinguish elements from each other. Unless otherwise specified, the drawings mentioned herein should not be interpreted as being drawn to scale. In addition, the drawings are generally simplified, and details or components are omitted for clarity of presentation and explanation. The drawings and discussion are used to explain the principles discussed below. DETAILED DESCRIPTION

[0040] The following detailed description is exemplary in nature 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 preceding background, summary and brief description of the drawings or the following detailed description.

[0041] 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 is apparent to one of ordinary skill in the art that the disclosed technology can be practiced without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0042] As used herein, the term "coupled" means directly connected to or connected through one or more intermediate components or circuits. In addition, throughout the application, ordinal numbers (e.g., first, second, third, etc.) can be used as adjectives of elements (i.e., any noun in the application). Unless explicitly disclosed (such as by using the terms "before", "after", "single" and other such terms), the use of ordinal numbers does not imply or create any specific ordering of elements, nor does it limit any element to only a single element. On the contrary, the use of ordinal numbers is to distinguish 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) the second element in the ordering of the element.

[0043] The present disclosure provides a device and method for backlight control of a panel display device, which includes multiple light sources (e.g., LEDs) to illuminate a display panel (e.g., an LCD panel or other light-transmitting display panel). In various embodiments, a backlight array including multiple light sources can be located behind the display panel, and the light sources can be configured to illuminate corresponding areas of the display panel, respectively. The brightness level of each light source can be individually controlled to achieve local dimming, which provides brighter and / or darker parts of a displayed image to enhance image contrast. In one embodiment, the brightness of each light source can be determined at least in part based on pixel data of a set of pixels located near each light source, wherein the pixel data of a pixel can include the grayscale level of the corresponding color (e.g., red, green, and blue) of the pixel.

[0044] In some embodiments, the brightness level of each light source can be determined based on the average picture level (APL) of the corresponding area of ​​the display panel illuminated by each light source. The APL can be calculated based on the pixel data of the pixels located in the area of ​​the display panel. In a typical embodiment, the brightness level of each light source increases as the APL increases. However, the brightness control based on the APL of the light source may suffer from the following problem: bright but small foreground objects can be displayed at a brightness level lower than the specified brightness level, as described below.

[0045] Figure 1AAn example of bright foreground objects (shown in white) having the same specified brightness level but different sizes displayed on a dark background (shown in black) is shown. Shown in FIG. 1 are four foreground objects 102, 104, 106, 108 having a high specified brightness level (e.g., a maximum brightness level). Foreground object 102 is the largest and foreground object 108 is the smallest. Because the APL of the area in which the largest foreground object 102 is displayed is relatively high, the area is illuminated at a high brightness level, and thus the foreground object 102 can be displayed at a high specified brightness level. In contrast, because the APL of the area in which the smallest foreground object 108 is displayed is relatively low, the area is illuminated only at a low brightness level, and thus the foreground object 108 can be displayed at a brightness level lower than the specified brightness level.

[0046] In other embodiments, the brightness level of each light source can be determined based on the maximum pixel brightness level of the corresponding area of ​​the display panel illuminated by each light source. The maximum pixel brightness level of a certain area referred to herein is the maximum value of the brightness levels of the pixels located in the area. However, when a bright but small foreground object moves between areas illuminated by adjacent light sources, controlling the brightness level of each light source based on the maximum pixel brightness level may cause flickering.

[0047] Figure 1B The foreground object 112 having the maximum brightness level is shown in FIG. Figure 1B ) moves from within region 116 of display panel 110 to region 114 of the background having the lowest brightness level (shown as a solid black line in FIG. Figure 1B An example of an embodiment of the invention is shown as a white square in FIG. Figure 1B The top display panel and graph are at time t1, the middle display panel and graph are at time t2 after time t1, and the bottom display panel and graph are at time t3 after time t2. Figure 1B , three consecutive regions 114, 116, and 118 are illuminated by three consecutive light sources 124, 126, and 128 located behind the regions 114, 116, and 118, respectively. Note that each light source can be configured to partially illuminate the nearby region as well as the region behind which each light is disposed. Light sources 124, 126, and 128 can be configured to illuminate regions 114, 116, and 118, respectively, based on the maximum pixel brightness in regions 114, 116, and 118.

[0048] exist Figure 1BIn the example shown, the movement of foreground object 112 may cause flickering or undesirable changes in the brightness level of the displayed image. In this example, when the entire foreground object 112 is within region 116 (e.g., at time t1), only light source 126 emits light, and when the entire foreground object 112 is within region 114 (e.g., at time t3), only light source 124 emits light. Although foreground object 102 crosses the boundary between regions 114 and 116 (e.g., at time t2), both light sources 124 and 126 emit light, and thus the brightness of the displayed image may increase. The increase in brightness may be perceived by the user as flickering.

[0049] The present disclosure provides various techniques for facilitating display of bright but small foreground objects with desired brightness levels while mitigating or eliminating flicker that can occur when bright but small foreground objects move in a displayed image. The following is a description of embodiments of the present disclosure.

[0050] Figure 2 1 shows an example configuration of a display device 1000 according to one or more embodiments. In the illustrated embodiment, the display device 1000 includes a display panel 200 and is configured to display a desired image on the display panel 200. Figure 2 The display panel 200 is shown to have a rectangular shape with right-angled corners, but the display panel 200 may have a different shape (eg, a rectangular shape with rounded corners). The display panel 200 may be a light-transmitting display panel such as an LCD panel.

[0051] The display device 1000 further includes a display driver 300, a backlight device 400, and a backlight driver 500. The display driver 300 is configured to drive the display panel 200 to display a desired image on the display panel 200. The backlight device 400 is configured to illuminate the display panel 200. The backlight device 400 includes an array of light sources 410. Note that the light sources 410 are arranged in a plurality of arrays. Figure 2 4 is shown in dashed lines because the light source 410 is located behind the display panel 200. Figure 2 64 light sources 410 are shown in the figure, but those skilled in the art will appreciate that the backlight device 400 may include more or less than 64 light sources 410. In actual embodiments, the backlight device 400 may include hundreds to thousands of light sources 410. In one embodiment, each light source 410 may include an LED or a different type of light source. In the illustrated embodiment, the light sources 410 are arranged in an array or matrix. In other embodiments, the light sources 410 may be arranged in an irregular or regular pattern. The backlight device 400 is coupled to a backlight driver 500. The backlight driver 500 is configured to drive the light sources 410 of the backlight device 400 under the control of the display driver 300 so that each light source 420 emits light having a brightness level specified by the display driver 300.

[0052] like Figure 3 As shown, the light source 410 is located behind the display panel 200 and is configured to illuminate a corresponding area of ​​the display panel 200. Note that an area of ​​the display panel 200 illuminated by one light source 410 may partially overlap another area of ​​the display panel 200 illuminated by another light source 410. Thus, a pixel of the display panel 200 may receive light from two or more light sources 410. Although Figure 3 Four light sources 410 are shown, but those skilled in the art will appreciate that the backlight device 400 may include more than four light sources 410 .

[0053] Figure 4 An example arrangement of light sources 410 according to one or more embodiments is shown. In the illustrated embodiment, the display panel 200 is divided into rectangular areas 210 arranged in rows and columns, and the light sources 410 are respectively located behind the corresponding areas 210. In one embodiment, the area 210 is square. In other embodiments, the area 210 can be defined in different shapes so that the area 210 completely covers the display panel 200. Each light source 410 is positioned so that the projection of each light source 410 on the display panel 200 is located at the center (e.g., geometric center) of a corresponding area 210. As used herein, the "corresponding area" 210 of the light source 410 refers to the area 210 including the projection of the light source 410. Each light source 410 mainly illuminates the corresponding area 210, but can also assist in illuminating at least a portion of the area 210 surrounding (e.g., adjacent to) the corresponding area 210.

[0054] Figure 5 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 memory 310, an image processing circuit 320, a driving circuit 330, and a backlight control circuit 340. The image memory 310 is configured to receive an input image to be displayed on the display panel 200 from an external image source (not shown), and store the received input image therein. The input image is transmitted and stored in the image memory 310 in the form of pixel data of pixels of the input image. In one embodiment, 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 embodiment, each pixel of the display panel 200 may include R, G, and B sub-pixels configured to display red, green, and blue, respectively, and the pixel data of each pixel may include R, G, and B grayscales that specify the brightness levels of the R, G, and B sub-pixels, respectively. In an alternative embodiment, the image memory 310 may be omitted, and the pixel data of the input image may be directly provided to the image processing circuit 320 and the backlight control circuit 340.

[0055] Image processing circuit 320 is configured to apply image processing to pixel data of an input image received from image memory 310 to generate processed pixel data. The image processing performed by image processing circuit 320 may include color adjustment, demura correction, deburring correction, image scaling, gamma conversion, or other image processing.

[0056] The driving circuit 330 is configured to receive the processed pixel data from the image processing circuit 320, and to drive the corresponding pixels provided in the display panel 200 based at least in part on the processed pixel data. In one embodiment, each pixel in the display panel 200 may include R, G, and B sub-pixels, and the processed pixel data may include the grayscale levels of the R, G, and B sub-pixels of each pixel. The driving circuit 330 may be configured to drive or update the R, G, and B sub-pixels of each pixel based at least in part on the processed pixel data to control the brightness levels of the R, G, and B sub-pixels specified by the processed pixel data.

[0057] The backlight control circuit 340 is configured to generate backlight control instructions based at least in part on the input image and provide the backlight control instructions to the backlight driver 500 to control the corresponding light source 410 of the backlight device 400 (in Figures 2 to 4 The backlight control instruction may include a specified brightness level of the corresponding light source 410. The backlight driver 500 is configured to drive the corresponding light source 410 so that the corresponding light source 410 emits light with the specified brightness level.

[0058] Figure 6 An example configuration of backlight control circuit 340 is shown in accordance with one or more embodiments. In the illustrated embodiment, backlight control circuit 340 includes image filtering and analysis circuit 350, modified local APL calculation circuit 360, base brightness level determination circuit 370, and brightness boost circuit 380.

[0059] The image filtering and analysis circuit 350 is configured to receive an input image and apply filtering and analysis to the input image. The following is a detailed description of the functionality of the image filtering and analysis circuit 350.

[0060] The image filtering and analysis circuit 350 is configured to select a target portion of the input image for each light source 410 such that the target portion selected for each light source 410 is displayed in a corresponding area of ​​the display panel 200 illuminated by each light source 410 . Fig. 7A An example selection of a target portion of an input image for light sources 410a and 410c is shown in accordance with one or more embodiments. Fig. 7A, region 210a is a corresponding region of light source 410a, and region 210c is a corresponding region of light source 410c. Region 210b is a region adjacent to region 210a corresponding to light source 410a, and region 210d is a region adjacent to region 210c corresponding to light source 410c. Light source 410b is eight light sources 410 adjacent to light source 410a, and light source 410d is eight light sources 410 adjacent to light source 410c.

[0061] In one embodiment, the target portion of the input image of the light source 410a is selected so that the target portion is displayed in the corresponding area 420a of the display panel 200, wherein the corresponding area 420a is defined as being illuminated by the light source 410a. In the illustrated embodiment, the corresponding area 420a has a boundary that transfers the projections of eight light sources 410b adjacent to the light source 410a to the display panel 200. The projections of four of the eight light sources 410b are at the four corners of the corresponding area 420a, and the projections of the other four adjacent light sources 410b are on the four edges of the corresponding area 420a. In the illustrated embodiment, the corresponding area 420a is a square.

[0062] Similarly, the target portion of the input image of the light source 410c is selected so that the target portion is displayed in the corresponding area 420c of the display panel 200, wherein the corresponding area 420c is defined as being illuminated by the light source 410c. In the illustrated embodiment, the corresponding area 420c has a boundary that transfers the projections of eight light sources 410d adjacent to the light source 410c to the display panel 200. The projections of four of the eight adjacent light sources 410d are at the four corners of the corresponding area 420c, and the projections of the other four adjacent light sources 410d are on the four edges of the corresponding area 420c. In the illustrated embodiment, the corresponding area 420c is a square.

[0063] The target portion of the input image of the other light sources 410 may be selected in a manner similar to the target portion of the light sources 410a and 410c. The target portion of each light source 410 may be selected differently as long as the area of ​​the display panel 200 in which the target portion of each light source 410 is displayed contains at least the corresponding area 210 of each light source 410.

[0064] It should be noted that target portions of the input images of adjacent light sources 410 may overlap each other. Fig. 7A In the example shown, the height and width of each target portion are twice the height and width of region 210, and the target portion of light source 410a partially overlaps the target portion of its adjacent light source 410b.

[0065] Return to reference Figure 6, the image filtering and analysis circuit 350 is further configured to apply the filter to the target portion of the input image of each light source 410 to generate a filtered image portion. In one or more embodiments, the 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 embodiment, 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.

[0066] Figure 7B An example of filter coefficients defined for pixels of a target portion for light source 410a (shown in FIG. 7 ) is shown in accordance with one or more embodiments. Figure 7B 4 is a portion of an input image including a target portion of light source 410a. Number 430a indicates a corresponding position of light source 410a in the input image, and number 430b indicates a corresponding position of an adjacent light source 410b in the input image. Number 440a indicates an outer boundary of the target portion of light source 410a.

[0067] The filter coefficients defined for pixels of the target portion of the light source 410a depend on the corresponding distances between the pixels of the target portion of the input image and the corresponding positions 430a of the light source 410a in the input image. In one embodiment, the filter coefficients defined for pixels of the target portion of the light source 410 increase as the corresponding distances between the pixels of the target portion of the input image and the corresponding positions 430a of the light source 410a in the input image decrease. In the illustrated embodiment, the filter coefficient for the pixel at the corresponding position 430a of the light source 410a is Wi (e.g., 1.0), which is the maximum filter coefficient, and the filter coefficient for the pixel at the outer boundary 440a of the target portion is zero. The filter coefficients defined for other pixels of the target portion of the light source 410a are values ​​between zero and Wi. The filter coefficients so defined are applied to the pixel data of the corresponding pixels of the target portion to generate a filtered image portion. The filter coefficients for pixels of other target portions of other light sources 410 can be defined in a manner similar to the filter coefficients defined for pixels of the target portion of the light source 410a, such as Figure 7B shown.

[0068] Return to reference Figure 6 The image filtering and analysis circuit 350 is further configured to analyze the filtered image portion of each light source 410 to determine a maximum pixel brightness level PL of the filtered image portion. MAX and the APL of the filtered image portion. This paper deals with the maximum pixel brightness level PL MAXis the maximum value of the brightness levels of the pixels of the filtered image portion. The APL of the filtered image portion (also referred to as the filtered image local APL) is the average value of the brightness levels of the pixels of the filtered image portion. The maximum pixel brightness level PL determined for each light source 410 is MAX The filtered image local APL is provided to the modified local APL calculation circuit 360 .

[0069] Figure 8 FIG. 2 shows an overview of image processing performed in the image filtering and analysis circuit 350 according to one or more embodiments. The image filtering and analysis circuit 350 is configured to first select a target portion of the input image for each light source 410. As discussed above, the target portion of the input image for each light source 410 is selected so that the target portion is displayed in the corresponding area of ​​the display panel 200 illuminated by each light source 410, as described with respect to FIG. Fig. 7A The image filtering and analysis circuit 350 is further configured to apply the filter to the target portion selected for each light source 410 to generate a filtered image portion. The image filtering and analysis circuit 350 is also configured to determine the maximum pixel brightness level PL of the filtered image portion generated for each light source 410. MAX and the filtered image local APL.

[0070] In one or more embodiments, the backlight control circuit 340 is configured to generate a filtered image local APL and a maximum pixel brightness level PL based on the filtered image portion generated for each light source 410. MAX The specified brightness level of each light source 410 is determined. The specified brightness level of each light source 410 is provided to the backlight driver 500, which controls the brightness level of each light source 410 in response to the specified brightness level. Determining the specified brightness level of each light source 410 based on the filtered image local APL effectively provides a local dimming function, while the maximum pixel brightness level PL is determined based on the maximum pixel brightness level PL MAX Determining the specified brightness level also effectively mitigates the undesirable reduction in brightness level of bright but small foreground objects. At the same time, the maximum pixel brightness level PL is determined using the filtered image portion (rather than the object portion). MAX This effectively mitigates flicker that can occur when a bright but small foreground object moves between areas illuminated by adjacent light sources, because the maximum pixel brightness level PL is lower when the bright but small foreground object is located midway between adjacent light sources. MAX reduce.

[0071] In an embodiment where the target portions of the input image selected for adjacent light sources 410 overlap each other, the target portions selected for adjacent light sources 410 share some pixels, and two or more filter coefficients defined for two or more light sources 410 are assigned to each shared pixel. In such an embodiment, the sum of the filter coefficients assigned to each shared pixel can be kept constant. This can effectively reduce flickering that may occur when a bright but small foreground object moves between areas illuminated by adjacent light sources. In an embodiment where the filter coefficient is a value in the range between 0.0 and 1.0 (including 0.0 and 1.0), the sum of the filter coefficients assigned to each shared pixel can be 1.0.

[0072] Fig. 9A An example of mitigating flicker when a foreground object 450 having a maximum brightness level moves from within region 210 - 3 to within region 210 - 2 of display panel 200 is shown according to one or more embodiments. Fig. 9A The top panel and graph show the time t 11 The next top panel and graph show the time t 11 After the time t 12 The bottom panel and graph at time t 12 After the time t 13 and the bottom panel and graph at time t 13 After the time t 14 Place.

[0073] Fig. 9A The left column shows regions 210-1, 210-2, and 210-3 of display panel 200 and a bright but small foreground object 450 that moves from within region 210-3 to within region 210-2 along a trajectory 460 that passes through the centers of regions 210-1, 210-2, and 210-3. Fig. 9A The middle column of 460 shows the filter coefficients assigned to the pixels arranged along the trajectory 460, and the right column shows the brightness levels of the light sources 410-1, 410-2 and 410-3, where the light sources 410-1, 410-2 and 410-3 are located behind the regions 210-1, 210-2 and 210-3, as shown in FIG. Fig. 9B In one embodiment, the projections of the light sources 410 - 1 , 410 - 2 , and 410 - 3 on the display panel are located at the centers of the regions 210 - 1 , 210 - 2 , and 210 - 3 , respectively.

[0074] Return to reference Fig. 9A, trend line 440-2 indicates the filter coefficients assigned to the pixels for generating the filtered image portion of light source 410-2, and trend line 440-3 indicates the filter coefficients assigned to the pixels for generating the filtered image portion of light source 410-3. The filter coefficients assigned to the pixels for generating the filtered image portion of light source 410-2 arranged along trajectory 460 increase toward the center of region 210-2 and take a maximum value of 1.0. Correspondingly, the filter coefficients assigned to the pixels for generating the filtered image portion of light source 410-3 arranged along trajectory 460 increase toward the center of region 210-3 and take a maximum value of 1.0. In the illustrated embodiment, the sum of the filter coefficients assigned to each pixel for generating the filtered image portion of light sources 410-2 and 410-3 remains constant over the pixels arranged along trajectory 460. In the illustrated embodiment, the sum of the filter coefficients assigned to each pixel remains constant at 1.0.

[0075] For example, as shown in the topmost graph in the middle column, a pixel at position 470-1 in region 210-3 is assigned a filter coefficient of 0.2 for generating a filtered image portion of light source 410-2, while being assigned a filter coefficient of 0.8 for generating a filtered image portion of light source 410-3. In addition, as shown in the second graph from the top, a pixel at position 470-2 at the boundary between regions 210-2 and 210-3 is assigned a filter coefficient of 0.5 for generating filtered image portions of both light sources 410-2 and 410-3. In addition, as shown in the second graph from the bottom, a pixel at position 470-3 in region 210-2 is assigned a filter coefficient of 0.66 for generating a filtered image portion of light source 410-2, while being assigned a filter coefficient of 0.34 for generating a filtered image portion of light source 410-3. Finally, as shown in the bottommost graph, pixels at center 470-4 of region 210-2 are assigned a filter coefficient of 1.0 for generating a filtered image portion of light source 410-2 and a filter coefficient of 0.0 for generating a filtered image portion of light source 410-3.

[0076] The illustrated assignment of filter coefficients to corresponding pixels effectively reduces changes in image brightness, thereby reducing or eliminating the occurrence of flicker. In the illustrated example, when the foreground object 450 is at time t 11 At position 470-1, since the filter coefficient used to generate the filtered image portion of light source 410-2 is 0.2 (ie, 20%), the maximum pixel brightness level PL of the filtered image portion generated for light source 410-2 is MAXis approximately 20%, and since the filter coefficient used to generate the filtered image portion of light source 410-3 is 0.8 (ie, 80%), the maximum pixel brightness level PL of the filtered image portion generated for light source 410-3 is MAX is about 80%. Fig. 9A As shown in the uppermost figure of the right column, the light source 410-2 emits light having a brightness level of approximately 20%, and the light source 410-3 emits light having a brightness level of approximately 80%.

[0077] When the foreground object 450 is at time t 12 At position 470-2, since the filter coefficient used to generate the filtered image portion of light sources 410-2 and 410-3 is 0.5 (i.e., 50%), the maximum pixel brightness level PL of the filtered image portion generated for light sources 410-2 and 410-3 is MAX are approximately 50%. Fig. 9A As shown in the second figure from the top of the right column, both light sources 410 - 2 and 410 - 3 emit light having a brightness level of approximately 50%.

[0078] When the foreground object 450 is at time t 13 At position 470-3, since the filter coefficient used to generate the filtered image portion of light source 410-2 is 0.66 (ie, 66%), the maximum pixel brightness level PL of the filtered image portion generated for light source 410-2 is MAX is approximately 66%, and since the filter coefficient used to generate the filtered image portion of light source 410-3 is 0.34 (ie, 34%), the maximum pixel brightness level PL of the filtered image portion generated for light source 410-3 is MAX is about 34%. Fig. 9A As shown in the second figure from the bottom of the right column, the light source 410-2 emits light having a brightness level of approximately 66%, and the light source 410-3 emits light having a brightness level of approximately 34%.

[0079] When the foreground object 450 is at time t 14 When located at the center 470-4 of the region 210-2, since the filter coefficient used to generate the filtered image portion of the light source 410-2 is 1.0 (i.e., 100%), the maximum pixel brightness level PL of the filtered image portion generated for the light source 410-2 is MAX is approximately 100%, and since the filter coefficient used to generate the filtered image portion of light source 410-3 is 0.0 (ie, 0%), the maximum pixel brightness level PL of the filtered image portion generated for light source 410-3 is MAXis approximately 0%. Fig. 9A As shown in the bottommost figure of the right column of , light source 410-2 emits light having a brightness level of approximately 100%, and light source 410-3 emits light having a brightness level of approximately 0%. Therefore, the sum of the brightness levels of light sources 410-2 and 410-3 remains approximately constant at 100%.

[0080] Return to reference Figure 6 The modified local APL calculation circuit 360, the base brightness level determination circuit 370 and the brightness boost circuit 380 together form a circuit configured to generate a maximum pixel brightness level PL of the filtered image portion for each light source 410 based on the maximum pixel brightness level PL MAX and the filtered image local APL to determine a specified brightness level for each light source 410. The operations of the modified local APL calculation circuit 360, the base brightness level determination circuit 370, and the brightness boost circuit 380 are described in detail below.

[0081] The modified local APL calculation circuit 360 is configured to calculate the maximum pixel brightness level PL of the filtered image portion generated for each light source 410 based on the maximum pixel brightness level PL MAX and the filtered image local APL to determine a modified local APL for each light source 410. In one embodiment, the modified local APL for each light source 410 may be the maximum pixel brightness level PL of the filtered image portion generated for each light source 410. MAX The weighted average of the local APL of the filtered image and the maximum pixel brightness level PL is determined based on the local APL of the filtered image. MAX and the weight of the local APL of the filtered image.

[0082] In some embodiments, the modified local APL calculation circuit 360 may include a maximum APL ratio lookup table (LUT) 365 that stores a ratio indicating the local APL of the filtered image and the maximum pixel brightness level assigned to it. MAX In such an embodiment, the modified local APL calculation circuit 360 may be configured to determine the weight assigned to the maximum pixel brightness level PL with reference to the maximum APL ratio LUT 365. MAX and the weights of the filtered image local APL, and the modified local APL is calculated as the maximum pixel brightness level PL using the determined weights MAX and the weighted average of the local APL of the filtered image.

[0083] Fig.10 FIG. 2 shows the local APL of a filtered image and the value assigned to the maximum pixel brightness level PL according to one or more embodiments. MAXNote that in the illustrated embodiment, the weights assigned to the maximum pixel brightness level PL MAX The sum of the weights of the local APL of the filtered image is 1.0. In summary, in the illustrated embodiment, the maximum pixel brightness level PL MAX The weight of decreases monotonically as the local APL of the filtered image increases. The following describes the relationship between the local APL of the filtered image and the value assigned to the maximum pixel brightness level PL MAX Details of example relationships between the weights of .

[0084] In the illustrated embodiment, when the filtered image local APL is zero, the maximum pixel brightness level PL MAX The weight of is p, where p is a number between 0.0 (or 0%) and 1.0 (or 100%). TH1 When the range is between MAX The weight of decreases monotonically as the local APL of the filtered image increases. Fig.10 shows the maximum pixel brightness level PL assigned to MAX The weight of α decreases linearly with the increase of the local APL of the filtered image, but the weight assigned to the maximum pixel brightness level PL MAX The weight of can be reduced nonlinearly as the local APL of the filtered image increases. When the local APL of the filtered image is greater than or equal to the threshold value X TH1 When the maximum pixel brightness level PL is assigned MAX The weight of is 0.0. In this case, the weight assigned to the filtered image-local APL is 1.0.

[0085] In the illustrated embodiment, when the filtered image local APL is X1 (which is zero and the threshold value X TH1 ) is assigned to the maximum pixel brightness level PL MAX The weight assigned to the local APL of the filtered image is 0.75 (or 75%) and the weight assigned to the local APL of the filtered image is 0.25 (or 25%). In this case, the modified local APL is the maximum pixel brightness level PL MAX The sum of 75% of the local APL of the filtered image and 25% of the local APL of the filtered image. When the local APL of the filtered image is X2 (which is greater than the threshold value X TH1 ), is assigned to the maximum pixel brightness level PL MAXThe weight assigned to the filtered image local APL is 0 (or 0%) and the weight assigned to the filtered image local APL is 1.0 (or 100%). In this case, the modified local APL is equal to the filtered image local APL. As described above, the modified local APL is calculated as the maximum pixel brightness level PL using the corresponding weight determined depending on the filtered image local APL. MAX The weighted average of the local APL of the filtered image.

[0086] Return to reference Figure 6 , the basic brightness level determination circuit 370 is configured to determine the basic brightness level of each light source 410 based on the modified local APL determined for each light source 410. In some embodiments, the basic brightness level determination circuit 370 may include a basic brightness LUT 375 that stores information indicating the relationship between the basic brightness level and the modified local APL of each light source 410. In such an embodiment, the basic brightness level determination circuit 370 may be configured to refer to the basic brightness LUT 375 to determine the basic brightness level of each light source 410 based on the modified local APL determined for each light source 410.

[0087] Fig.11 An example relationship between a base brightness level and a modified local APL for each light source 410 according to one or more embodiments is shown. The base brightness level for each light source 410 increases monotonically as the modified local APL determined for each light source 410 increases. In the illustrated embodiment, the base brightness level increases non-linearly as the modified local APL increases. In other embodiments, the base brightness level may increase linearly as the modified local APL increases. In embodiments where the base brightness level determination circuit 370 includes a base brightness LUT 375, the base brightness LUT 375 may store values ​​of the base brightness level for corresponding values ​​of the modified local APL.

[0088] Return to reference Figure 6 , the brightness boost circuit 380 is configured to determine the specified brightness level of each light source 410 based on the base brightness level of each light source 410 and the filtered image local APL of the filtered image portion generated for each light source 410. In one or more embodiments, determining the specified brightness level of each light source 410 includes determining a boost factor based on the filtered image local APL of each light source 410, and applying the boost factor to the base brightness level of each light source 410. The boost factor determines whether to perform "boosting" when determining the specified brightness level. "Boosting" mentioned herein is used to determine that the specified brightness level is higher than the base brightness level. In the illustrated embodiment, the boost factor is determined so that when the filtered image local APL is less than the threshold value XTH2 A "boost" is performed when the specified brightness level is higher than the base brightness level. TH2 , the boost factor is determined so that "boost" is not performed. In this case, the specified brightness level is equal to the base brightness level. In one embodiment, the specified brightness level of each light source 410 can be determined by multiplying the base brightness level by the boost factor.

[0089] The brightness boost circuit 380 may include a boost LUT 385 storing information indicating a relationship between a boost factor and a filtered image local APL. In such an embodiment, the brightness boost circuit 380 may be configured to reference the boost LUT 385 to determine the boost factor.

[0090] Fig.12 An example relationship between a lifting factor and a filtered image local APL is shown in accordance with one or more embodiments. Fig.12 The relationship shown in can be used in embodiments where the specified brightness level of each light source 410 is determined by multiplying the base brightness level of each light source 410 by the boost factor. In the illustrated embodiment, when the filtered image local APL is greater than or equal to the threshold value X TH2 (i.e., no “boosting” is performed), the boosting factor is 1.0 (or 100%), and when the filtered image local APL is less than the threshold X TH2 (i.e., performing "boosting"), the boosting factor is greater than 1.0 (or greater than 100%). More specifically, when the filtered image local APL is less than or equal to the threshold value X TH3 (where q is greater than 1.0), the boost factor is the maximum value q (or 100 q%). In one embodiment, the maximum value q may be 3.0 (or 300%). In other embodiments, the maximum value q may be a different value greater than 1.0. When the filtered image local APL is below the threshold value X TH3 With X TH2 In the range between , the lift factor decreases from q to 1.0 as the local APL of the filtered image increases. Fig.12 The boost factor is shown to decrease linearly from q to 1.0, but the boost factor may decrease non-linearly.

[0091] The boost factor is determined to allow the specified brightness level of the light source 410 to exceed the full white brightness level of a portion of the allowed range of the filtered image local APL for the filtered image portion generated by the light source 410. The full white brightness level referred to herein is the brightness level of the light source 410 where the pixel brightness levels of all pixels of the target portion selected for the light source 410 have the maximum pixel brightness. In the illustrated embodiment, at least when the filtered image local APL is less than or equal to the threshold value XTH3 When , the maximum value q of the boost factor is determined to allow the specified brightness level of the light source 410 to exceed the full white brightness level. This means that when a bright but small foreground object is displayed in the target portion selected for the light source, the specified brightness level of the light source 410 is "boosted" to allow the foreground object to be displayed at the desired high brightness level.

[0092] The designated brightness level of each light source 410 determined based on the base brightness level and the boost factor is provided to the backlight driver 500 ( Figure 5 The backlight driver 500 drives each light source 410 to allow each light source 410 to emit light having a designated brightness level determined for each light source 410 .

[0093] Fig.13A Example operations for displaying bright foreground objects represented by numerals 602, 604, 606, and 608, respectively, on a dark background are shown in accordance with one or more embodiments. Dashed lines 612 and 614 indicate example relationships between base brightness levels and modified local APLs, and solid lines 622, 624, 626, and 628 indicate example relationships between specified brightness levels and modified local APLs. Bright foreground objects 602, 604, 606, and 608 are of different sizes. Foreground object 602 is the smallest, and foreground object 604 is the second smallest.

[0094] In the illustrated embodiment, bright foreground objects 602 and 604 result in larger values ​​of the modified local APL because the maximum pixel brightness level PL MAX is large. In addition, "boosting" is performed to display bright foreground objects 602 and 604 because the local APL of the filtered image is low. Performing "boosting" facilitates displaying bright foreground objects 602 and 604 of small size at high brightness levels as needed. Fig.13A In the embodiment shown in , the boost factor for bright foreground object 602 is 120% (or 1.2), and the boost factor for bright foreground object 604 is 105% (or 1.05). At the same time, when displaying bright foreground objects 606 and 608 with large sizes, the "boost" function is disabled because the filtered image local APL is high. Therefore, the specified brightness levels of bright foreground objects 606 and 608 are equal to the base brightness levels of bright foreground objects 606 and 608, respectively.

[0095] Fig. 13BAn example operation for displaying grayscale images represented by numerals 632, 634, 636, and 638, respectively, is shown in accordance with one or more embodiments. Dashed lines 642 and 644 indicate an example relationship between a base brightness level and a modified local APL, and solid lines 652, 654, 656, and 658 indicate an example relationship between a specified brightness level and a modified local APL. Grayscale images 632, 634, 636, and 638 have different brightness levels. Grayscale image 632 is the darkest, and grayscale image 634 is the second darkest.

[0096] In the illustrated embodiment, the grayscale images 632 and 634 result in smaller values ​​of the modified local APL because the maximum pixel brightness level PL MAX and the filtered image local APL are both low. Although "boost" is performed on grayscale images 632 and 634, the specified brightness level is low due to the smaller value of the modified local APL. Therefore, grayscale images 632 and 634 are displayed at a low brightness level as required. At the same time, when grayscale images 636 and 638 are displayed, the "boost" function is disabled because the filtered image local APL is high. Therefore, the specified brightness levels of grayscale images 636 and 638 are equal to the base brightness levels of grayscale images 636 and 638, respectively.

[0097] Fig.14A An example image is shown for which the "boost" function is advantageous in accordance with one or more embodiments. The "boost" function is advantageous in displaying an image in which a bright but small foreground object is displayed, such as an image of fireworks as shown. The "boost" function allows the bright but small foreground object to be displayed at a desired high brightness level.

[0098] Fig. 14B An example image is shown for which the "boost" function is disabled in accordance with one or more embodiments. The "boost" function does not work when an image is displayed with reduced brightness level variations, such as a landscape image. When the "boost" function is disabled, local dimming is performed based on the filtered image local APL to enhance image contrast.

[0099] Fig.15 FIG. 1 shows an example configuration of a backlight control circuit 1340 according to other embodiments. Figure 6The backlight control circuit 340 shown is similarly configured, except that the backlight control circuit 1340 includes a brightness boost circuit 1380 instead of the brightness boost circuit 380, and additionally includes a global APL calculation circuit 1390. The global APL calculation circuit 1390 is configured to calculate a global APL, which is the APL (or average value of pixel brightness levels) of the entire input image. The global APL calculation circuit 1390 is also configured to provide the global APL to the brightness boost circuit 1380.

[0100] The brightness boost circuit 1380 is configured similar to Figure 6 The brightness boost circuit 1380 shown in determines the specified brightness level of each light source 410, except that the brightness boost circuit 1380 uses the global APL instead of the filtered image local APL. In one or more embodiments, the brightness boost circuit 1380 is configured to determine the boost factor based on the global APL, and apply the boost factor to the base brightness level of each light source 410. In one embodiment, the specified brightness level of each light source 410 can be determined by multiplying the base brightness level by the boost factor. The brightness boost circuit 1380 may include a boost LUT 1385 storing information indicating the relationship between the boost factor and the global APL. In such an embodiment, the brightness boost circuit 1380 may be configured to refer to the boost LUT 1385 to determine the boost factor. Using the global APL to determine the boost factor, rather than the filtered image local APL, will facilitate appropriately determining the boost factor when a bright foreground image having a size greater than the target portion of the input image of each light source 410 is displayed on the display panel 200.

[0101] Fig.16 An example relationship between a boost factor and a global APL is shown in accordance with one or more embodiments. Fig.16 The relationship shown in can be used in embodiments where the specified brightness level of each light source 410 is determined by multiplying the base brightness level of each light source 410 by the boost factor. In the illustrated embodiment, when the global APL is greater than or equal to the threshold value X TH4 (i.e., no “boosting” is performed), the boost factor is 1.0 (or 100%), and when the global APL is less than the threshold X TH4 (i.e., performing "boosting"), the boost factor is greater than 1.0 (or greater than 100%). More specifically, when the global APL is less than or equal to the threshold value X TH5 When the global APL is below the threshold value X, the boost factor is the maximum value q (or 100q%), where q is a value greater than 1.0. In one embodiment, the maximum value q may be 3.0 (or 300%). In other embodiments, the maximum value q may be a different value greater than 1.0. TH5 and X TH4In the range between , the boost factor decreases from q to 1.0 as the global APL increases. Fig.16 The boost factor is shown to decrease linearly from q to 1.0, but the boost factor may decrease non-linearly.

[0102] Fig.17 is an example configuration of the backlight control circuit 2340 according to still other embodiments. Figure 6 The backlight control circuit 340 shown is similarly configured, except that the backlight control circuit 2340 also includes a brightness adjustment circuit 2310, which is configured to adjust the specified brightness level of each light source 410 based on a display brightness value (DBV). The DBV referred to herein is a value that specifies the desired display brightness level of the display device 1000, wherein the display brightness level referred to herein is the overall brightness level of the display image displayed on the display panel 200. In the illustrated embodiment, the backlight control circuit 2340 also includes a DBV generation circuit 2320, which is configured to determine the DBV based on the ambient light brightness level LUX measured by the ambient light sensor 2330. In other embodiments, the DBV can be generated by a controller external to the display driver 300. The DBV can be generated based on a user operation other than the ambient light brightness level LUX. For example, when an instruction to adjust the display brightness level of the display device 1000 is manually input to an input device, a DBV can be generated based on the instruction.

[0103] Fig.18A 2 shows an example relationship between the ambient light brightness level LUX and DBV according to one or more embodiments. In the illustrated embodiment, as the ambient light brightness level LUX increases, DBV increases monotonically. Fig.18A It is shown that the DBV increases linearly as the ambient light brightness level LUX increases, but the DBV may increase nonlinearly as the ambient light brightness level LUX increases.

[0104] Fig.18B 1 shows another example relationship between the ambient light brightness level LUX and DBV according to one or more embodiments. In one or more embodiments, as the ambient light brightness level LUX increases, DBV increases stepwise. In the illustrated embodiment, DBV has a hysteresis dependency on the ambient light brightness level LUX. More specifically, at the ambient light brightness level LUX, DBV increases stepwise. 1U Under this condition, DBV increases from VL1 to VL2, and when the brightness level is lower than the ambient light level L 1U The ambient light level L 1D Similarly, for j between 2 and 5 (including the end values), at the ambient light brightness level L jU Next, DBV from VLj Increase to VL j+1 , and below the ambient light level L jU The ambient light level L jD Next, DBV from VL j+1 Reduce to VL j .

[0105] Return to reference Fig.17 , the backlight control circuit 2340 can be configured to generate a specified backlight value for each light source 410 by modifying the base brightness level of each light source 410 by the brightness boost circuit 380 and the brightness adjustment circuit 2310. In one or more embodiments, the brightness boost circuit 380 can be configured to determine the boost factor based on the filtered image local APL of each light source 410, and the brightness adjustment circuit 2310 can be configured to determine the brightness adjustment factor based on the DBV. Figure 6 and Fig.12 The boost LUT 385 described above determines the boost factor. The brightness adjustment factor can be determined so that the brightness adjustment factor increases as the DBV increases. The backlight control circuit 2340 can be configured to generate a specified backlight value for each light source 410 by applying the boost factor and the brightness adjustment factor to the base brightness level of each light source 410. In one embodiment, the backlight control circuit 2340 can be configured to generate a specified backlight value for each light source 410 by multiplying the base brightness level of each light source 410 by the boost factor and further multiplying the result by the brightness adjustment factor. Using the boost factor to determine the specified backlight value implements the above-mentioned Figure 6 and Fig.12 The "boost" function discussed. Using the brightness adjustment factor to determine the specified backlight value allows the display brightness level of the panel display device to be adjusted to improve the visibility of the image displayed on the display panel 200. In particular, in an embodiment in which DBV is determined based on the ambient light brightness level LUX, using the brightness adjustment factor determined based on DBV allows the display brightness level of the panel display device to be appropriately adjusted according to the ambient light brightness level LUX.

[0106] Fig.19 An example of controlling DBV in response to an environment in which a panel display device is used according to one or more embodiments is shown. In a bright environment (e.g., a clear environment), in response to the ambient light brightness level LUX being high, DBV is determined to be a "high" value. In a medium brightness environment (e.g., a cloudy environment), in response to the ambient light brightness level LUX being medium, DBV is determined to be a "medium" value lower than the "high" value. In a dark environment (e.g., a night environment), in response to the ambient light brightness level LUX being low, DBV is determined to be a "low" value lower than the "medium" value.

[0107] The specified brightness level of the corresponding light source 410 is adjusted depending on DBV to adjust the display brightness level of the panel display device depending on the ambient light brightness level LUX. In a bright environment, the specified brightness level of the corresponding light source 410 increases in response to an increase in DBV to display an image at an increased display brightness level. In a dark environment, the specified brightness level of the corresponding light source 410 decreases in response to a decrease in DBV to display an image at a decreased display brightness level.

[0108] In addition, when a small bright foreground object is displayed on a dark background image, the specified brightness level of the one or more light sources 410 that illuminate the area of ​​the display panel 200 where the small bright foreground object is displayed is increased. However, when the display device is used in a dark environment, this may cause a halo effect (or halo) because light emitted from the one or more light sources 410 may bleed into the surrounding area of ​​the small bright foreground object, and human vision is sensitive to bleeding light in a dark environment.

[0109] The halo effect may be undesirably enhanced when performing the "boost" function, which helps to display small bright foreground objects at a desired high brightness level, such as Fig.14A The boost function increases the brightness level of one or more light sources illuminating an area in which a small bright object is displayed, which can increase the bleeding of light to areas surrounding the small bright foreground object to enhance the halo effect. The following describes an embodiment for mitigating the halo effect that may occur when a small bright object is displayed on a dark background image in a dark environment.

[0110] Fig. 20 FIG. 3 shows an example configuration of a backlight control circuit 3340 according to some further embodiments. Fig.17 The illustrated backlight control circuit 2340 is similarly configured, except that the backlight control circuit 3340 includes a compensation ratio determination circuit 3350 and a modified local APL calculation circuit 3360 instead of the modified local APL calculation circuit 360 .

[0111] The compensation ratio determination circuit 3350 is configured to determine the compensation ratio based on the DBV received from the DBV generation circuit 2320. As discussed in more detail later, the compensation ratio is used to suppress the brightness level of one or more light sources 410 that illuminate an area of ​​the display panel 200, where a small bright foreground object is displayed in the area when the display device is used in a dark environment. In one embodiment, the compensation ratio determination circuit 3350 may include a compensation ratio LUT 3355 that contains information indicating the relationship between the DBV and the compensation ratio and is configured to refer to the compensation ratio LUT 3355 to determine the compensation ratio based on the DBV. The compensation ratio is provided to the modified local APL calculation circuit 3360.

[0112] Fig.21 An example relationship between DBV and compensation ratio according to one or more embodiments is shown. In the illustrated embodiment, when DBV is less than a threshold DBV TH The compensation ratio increases as DBV increases, and when DBV is greater than or equal to the threshold DBV TH The compensation ratio is fixed to 1.0. Fig.21 When DBV is less than the threshold DBV TH The compensation ratio increases linearly with the increase of DBV, but the compensation ratio may increase nonlinearly. Of course, the disclosed embodiments contemplate that when DBV is greater than or equal to the threshold DBV TH , the compensation ratio can be fixed at a value other than 1.0.

[0113] Return to reference Fig. 20 The modified local APL calculation circuit 3360 is configured to receive the compensation ratio from the compensation ratio determination circuit 3350 and determine the modified local APL as the maximum pixel brightness level PL of the filtered image portion generated for each light source 410. MAX and a weighted average of the local APL of the filtered image, while using the compensation ratio to modify the value assigned to the maximum pixel brightness level PL in determining the modified local APL MAX In some embodiments, the modified local APL calculation circuit 3360 may be configured to use the weights of Fig.10 The depicted maximum APL ratio LUT 365 determines the maximum pixel brightness level PL assigned to it based on the filtered image local APL. MAX The weight of , and based on the compensation ratio, modify the maximum pixel brightness level PL MAX Determine the weight. Maximum pixel brightness level PL MAX The resulting weight may be referred to as the maximum pixel brightness level PL in the following text. MAXIn one embodiment, the modified local APL calculation circuit 3360 may be configured to compensate the initial maximum pixel brightness level PL by MAX The maximum pixel brightness level PL is calculated by multiplying the compensation ratio by the weight MAX The modified local APL calculation circuit 3360 may be further configured to calculate the maximum pixel brightness level PL by subtracting it from 1.0. MAX The modified local APL calculation circuit 3360 may also be configured to calculate the compensation weight of the local APL of the filtered image based on the maximum pixel brightness level PL MAX and the compensation weight determined by the filtered image local APL, and the modified local APL is determined as the maximum pixel brightness level PL MAX and the weighted average of the local APL of the filtered image.

[0114] Fig.22A FIG. 4 shows a maximum pixel brightness level PL when a panel display device is used in a bright environment according to one or more embodiments. MAX An example of the relationship between the compensation weight and the filtered image local APL. In an embodiment where DBV is determined based on the ambient light brightness level LUX, when the display device is used in a bright environment, DBV may be greater than the threshold DBV TH In this case, the compensation ratio can be determined as 1.0 (see Fig.21 ), and for the maximum pixel brightness level PL MAX The determined compensation weight may be determined to be equal to the value initially assigned to the maximum pixel brightness level PL MAX The weight of .

[0115] Fig. 22B FIG. 4 shows a maximum pixel brightness level PL when a panel display device is used in a dark environment according to one or more embodiments. MAX An example of the relationship between the compensation weight of and the filtered image local APL. In an embodiment where DBV is determined based on the ambient light brightness level LUX, when the display device is used in a dark environment, DBV may be less than the threshold DBV TH In this case, the value initially assigned to the maximum pixel brightness level PL is modified based on the compensation ratio MAX The weights are used to determine the maximum pixel brightness level PL MAX The determined compensation weight is less than the value initially assigned to the maximum pixel brightness level PL MAX This effectively suppresses the halo effect that may occur when displaying small bright foreground objects on a dark background image, because the maximum pixel brightness level PL MAXis a parameter that determines the brightness level of one or more light sources 410 that illuminate an area of ​​the display panel 200 where a small bright foreground object is displayed.

[0116] Fig.23 is a flow chart of an exemplary process 1700 for controlling a light source of a backlight device according to one or more embodiments. Process 1700 may be performed by Figure 2 and 3 The display device 1000 shown in FIG. Figure 5 However, it will be appreciated that the display driver 300 shown in FIG. Figure 2 and Figure 3 A display device with additional and / or fewer components as shown in FIG. 17 may be used to perform process 1700 , any of the following steps may be performed in any suitable order, and process 1700 may be performed in any suitable environment.

[0117] In one or more embodiments, process 1700 includes updating a display panel (eg, Figure 2 , Figure 3 and Figure 5 The process also includes, at step 1704, using a backlight device (e.g., Figure 2 , Figure 3 and Figure 5 The backlight device 400 shown in FIG. Figure 2 and Figure 3 The process 1700 further comprises applying the filter to the target portion of the input image to generate a filtered image portion at step 1706. The target portion of the input image is displayed in a corresponding area of ​​the display panel illuminated by the target light source among the plurality of light sources (e.g., areas 420a and 420c shown in FIG. 7). The process 1700 further comprises controlling the brightness level of the target light source based on the maximum pixel brightness level of the filtered image portion and the local average picture level (APL) of the filtered image portion at step 1708.

[0118] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0119] The use of the terms "one" and "an" and "the" and "at least one" and similar indicators (especially in the context of the following claims) in the context of describing the present invention should be interpreted as covering the singular and plural, unless otherwise specified herein or clearly contradicted by the context. The use of the term "at least one" followed by the enumeration of one or more items (e.g., "at least one of A and B") should be interpreted as meaning an item (A or B) selected from the listed items or any combination of two or more items in the listed items (A and B), unless otherwise specified herein or clearly contradicted by the context. Unless otherwise specified, the terms "comprising", "having", "including" and "containing" should be interpreted as open terms (i.e., meaning "including but not limited to"). Unless otherwise specified herein, the enumeration of the value ranges herein is intended only to be used as a shorthand method for individually referring to each individual value falling within the range, and each individual value is incorporated into the specification as if it were individually narrated herein. All methods described herein can be performed in any suitable order, unless otherwise specified herein or otherwise clearly contradicted by the context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0120] 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 those skilled in the art to adopt these variations where appropriate, and the inventors intend to practice the present invention in a manner other than as specifically described herein. Therefore, the present invention includes all modifications and equivalents of the subject matter recorded in the appended claims as permitted by applicable law. In addition, unless otherwise specified herein or otherwise clearly contradictory to the context, any combination of the above elements in all possible variations thereof is encompassed by the present invention.

Claims

1. A display device, comprising: a backlight device comprising a plurality of light sources configured to illuminate the display panel; as well as A backlight control circuit is configured to: applying a filter to a target portion of an input image to generate a filtered image portion, wherein the target portion of the input image is displayed in a corresponding area of ​​the display panel illuminated by a target light source from among the plurality of light sources; as well as The brightness level of the target light source is controlled based on a maximum pixel brightness level of the filtered image portion and a local average picture level APL of the filtered image portion.

2. The display device according to claim 1, wherein the filter comprises filter coefficients assigned to corresponding pixels of the target portion of the input image, wherein applying the filter to the target portion of the input image comprises applying the filter coefficients to pixel brightness levels of the pixels of the target portion of the input image, and The filter coefficients are defined depending on respective distances between the pixels of the target portion of the input image and corresponding positions of the target light source in the input image.

3. The display device according to claim 1, wherein determining the brightness level of the target light source comprises: calculating a modified local APL as a weighted average of the maximum pixel brightness level of the filtered image portion and the local APL of the filtered image portion; as well as The brightness level of the target light source is determined based on the modified local APL.

4. The display device of claim 3 , wherein calculating the modified local APL comprises: determining a weight assigned to the maximum pixel brightness level; as well as The weighted average is calculated using the determined weights.

5. The display device of claim 4, wherein determining the weight assigned to the maximum pixel brightness level is based on the local APL of the filtered image portion. 6 . The display device of claim 4 , wherein determining the weight assigned to the maximum pixel brightness level is further based on a display brightness level DBV of the display device.

7. The display device of claim 5, further comprising an ambient light sensor configured to measure a brightness level of ambient light, The determination of DBV is based on the ambient light brightness level.

8. The display device of claim 3 , wherein determining the brightness level of the target light source based on the modified local APL comprises: determining a base brightness level based on the modified local APL; determining a lifting factor, the lifting factor being determined based on the local APL of the filtered image portion; as well as Based on the base brightness level and the boost factor, the brightness level of the target light source is determined such that when the local APL of the filtered image portion is less than a threshold, the brightness level of the target light source is higher than the base brightness level.

9. The display device of claim 8, wherein calculating the modified local APL comprises: determining a weight assigned to the maximum pixel brightness level based on the local APL of the filtered image portion; as well as The weighted average is calculated using the determined weights.

10. The display device of claim 8, wherein determining the brightness level of the target light source comprises multiplying the base brightness level by the boost factor, and Wherein determining the lifting factor comprises determining that the lifting factor is greater than one when the local APL of the filtered image portion is less than the threshold.

11. The display device of claim 8, wherein the boost factor is determined based on pixel brightness levels of all pixels of the target portion of the input image having maximum pixel brightness to allow the brightness level of the target light source to exceed a full white brightness level that is the brightness level of the target light source.

12. The display device of claim 3 , wherein determining the brightness level of the target light source based on the modified local APL comprises: determining a base brightness level based on the modified local APL; determining a lifting factor, the lifting factor being determined based on the overall global APL of the input image; as well as Based on the basic brightness level and the boost factor, the brightness level of the target light source is determined such that when the global APL of the input image is less than a threshold, the brightness level of the target light source is higher than the basic brightness level.

13. The display device of claim 12, wherein determining the brightness level of the target light source comprises multiplying the base brightness level by the boost factor, and Wherein determining the lifting factor comprises determining that the lifting factor is greater than one when the global APL of the input image is less than the threshold.

14. A display driver comprising: a backlight control circuit coupled to a backlight device including a plurality of light sources for illuminating a display panel, wherein the backlight control circuit is configured to: applying a filter to a target portion of an input image to generate a filtered image portion, wherein the target portion of the input image is displayed in a corresponding area of ​​the display panel illuminated by a target light source from among the plurality of light sources; as well as The brightness level of the target light source is controlled based on a maximum pixel brightness level of the filtered image portion and a local average picture level APL of the filtered image portion.

15. The display driver of claim 14, wherein the filter comprises filter coefficients assigned to corresponding pixels in the target portion of the input image, wherein applying the filter to the target portion of the input image comprises applying the filter coefficients to pixel brightness levels of the pixels of the target portion of the input image, and The filter coefficients are defined depending on respective distances between the pixels of the target portion of the input image and corresponding positions of the target light source in the input image.

16. The display driver of claim 15, wherein determining the brightness level of the target light source comprises: calculating a modified local APL as a weighted average of the maximum pixel brightness level and the local APL for the filtered image portion; as well as The brightness level of the target light source is determined based on the modified local APL.

17. The display driver of claim 16, wherein calculating the modified local APL comprises: determining a weight assigned to the maximum pixel brightness level; as well as The weighted average is calculated using the determined weights.

18. The display driver of claim 17, wherein determining the weight assigned to the maximum pixel brightness level is based on the local APL of the filtered image portion.

19. The display driver of claim 17, wherein determining the weight assigned to the maximum pixel brightness level is further based on a DBV of a display device including the display driver.

20. A method comprising: illuminating the display panel using a plurality of light sources of a backlight device; applying a filter to a target portion of an input image to generate a filtered image portion, wherein the target portion of the input image is displayed in a corresponding area of ​​the display panel illuminated by a target light source from among the plurality of light sources; as well as The brightness level of the target light source is controlled based on a maximum pixel brightness level of the filtered image portion and a local average picture level APL of the filtered image portion.

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