Image display control device, image display system, and image display control method

Abstract

This image display control device having a local dimming function comprises: a brightness control unit that, on the basis of first image information, controls the brightnesses of a plurality of light sources included in a backlight; and a pixel compensation unit that, on the basis of the brightnesses of the plurality of light sources, generates second image information from the first image information. A first statistics acquisition unit acquires first statistical data of pixel values included in the first image information. A second statistics acquisition unit acquires second statistical data of pixel values included in the second image information. Consequently, an abnormality detection unit can detect an abnormality in the brightness control unit or pixel compensation unit for performing local dimming processing on the basis of the amount of deviation of the second statistical data from the first statistical data.

Description

[Technical Field]

[0001] The present invention relates to an image display control device, an image display system, and an image display control method. [Background technology]

[0002] Among display devices that use multiple light sources as backlights, there are known display devices that can quickly report the location of a faulty light source among the multiple light sources. Also, there are known display control devices that can verify whether the data displayed on the display device is normal by performing a cyclic redundancy check on the image data. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-3472 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-35677 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, there has been an increasing demand for local dimming processing in image display control devices that display images on a display device having a backlight. If an abnormality occurs in a processing unit that performs local dimming processing in an image display control device, the brightness or color of the image displayed on the display device may change. However, changes in the brightness or color of the image may not be detectable by a cyclic redundancy check of image data. Furthermore, image display control devices for vehicles may display icons on the display device as images to alert the driver, etc. This type of icon must meet the requirements of ASIL (Automotive Safety Integrity Level), so it is preferable to detect changes in the image due to an abnormality in the local dimming unit.

[0005] The present invention has been made in view of the above-mentioned points, and has an object to provide an image display control device that can determine an abnormality in a processing unit that performs local dimming processing. [Means for solving the problem]

[0006] In one aspect of the present invention, an image display control device is an image display control device having a local dimming function, and includes a brightness control unit that controls the brightness of multiple light sources included in a backlight based on first image information that indicates an image to be displayed on a display unit, a pixel compensation unit that corrects pixel values ​​included in the first image information based on the brightness of the multiple light sources to generate second image information, a first statistical acquisition unit that acquires first statistical data of pixel values ​​included in the first image information, a second statistical acquisition unit that acquires second statistical data of pixel values ​​included in the second image information, and an abnormality detection unit that detects an abnormality in the brightness control unit or the pixel compensation unit based on the amount of deviation of the second statistical data from the first statistical data. [Effects of the Invention]

[0007] According to the disclosed technique, it is possible to provide an image display control device that can determine whether there is an abnormality in a processing unit that performs local dimming processing. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing an example of an image display system according to a first embodiment. [Figure 2] FIG. 2 is a block diagram illustrating an example of a display controller of FIG. 1. [Figure 3] 3 is a block diagram showing an example of a local dimming unit shown in FIG. 2. FIG. [Figure 4] 4 is a diagram showing an example of controlling the luminance of a backlight by the luminance control unit of FIG. 3. FIG. [Figure 5] 4 is a diagram showing an example of generating a luminance distribution by the luminance distribution calculation unit in FIG. 3. FIG. [Figure 6] 4 is a diagram showing an example of correcting the luminance of an image by the RGB correction unit in FIG. 3. FIG. [Figure 7] 4 is a diagram showing an example of statistical information acquired by an input statistics acquisition unit and an output statistics acquisition unit in FIG. 3. FIG. [Figure 8] 4 is a diagram illustrating an example of determining an abnormality in a local dimming unit by the processor in FIG. 3. FIG. [Figure 9] 4 is a flowchart showing an example of a process for determining an abnormality in a local dimming unit by the processor of FIG. 3. [Figure 10] FIG. 10 is a flowchart showing an example of the process of step S80 in FIG. 9. [Figure 11] 10A and 10B are diagrams illustrating an example of the operation of a processor included in a display controller in an image display system according to a second embodiment. [Figure 12] 12 is a flowchart showing an example of processing for determining an abnormality in a local dimming unit by a processor that performs the operation of FIG. 11. FIG. [Figure 13] FIG. 11 is a diagram showing an example of the operation of a processor mounted on a display controller in an image display system according to the third embodiment. [Figure 14] 14 is a flowchart showing an example of processing for determining an abnormality in a local dimming unit by a processor that performs the operation of FIG. 13. [Figure 15] FIG. 15 is a flowchart showing an example of the process of step S14 in FIG. [Figure 16] FIG. 10 is a block diagram showing an example of a display controller installed in an image display system according to a fourth embodiment. [Figure 17] FIG. 17 is a block diagram showing an example of a local dimming unit in FIG. 16. [Figure 18] 18 is a diagram showing an example of statistical data acquired by the internal statistics acquisition unit of FIG. 17. FIG. [Figure 19] 18 is a flowchart showing an example of processing performed by the processor of FIG. 17 to determine whether there is an abnormality in the local dimming unit. [Figure 20] 10A and 10B are diagrams illustrating an example of a frame image used to determine whether or not there is an abnormality in a local dimming unit. [Figure 21]FIG. 11 is a block diagram showing an example of a display controller installed in an image display system according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. In the following description, image data may be simply referred to as an image.

[0010] (First embodiment) Fig. 1 is a block diagram showing an example of an image display system according to the first embodiment. The image display system 1 shown in Fig. 1 includes a head unit 10, a serializer 20, a deserializer 30, a display controller 40, and a display device 70 including a display 50 and a backlight 60.

[0011] The head unit 10 generates an image to be displayed on the display 50. The head unit 10 also outputs image data 10a and control information 10b corresponding to the generated image to the serializer 20. For example, the control information 10b includes information used for controlling the display of the image on the display 50. For example, the image data 10a may include a superimposed image such as an icon superimposed on the original image. An example in which the superimposed image superimposed on the original image is an icon will be described below.

[0012] The serializer 20 converts the image data 10a and control information 10b output from the head unit 10 into serial data 20a. The serializer 20 transmits the serial data 20a obtained by the conversion to the deserializer 30 via a single video link (transmission line). Although not particularly limited, the transmission and reception of the serial data 20a via the video link is performed using an interface such as LVDS (Low Voltage Differential Signaling) or APIX (Automotive Pixel Link: registered trademark).

[0013] The deserializer 30 converts the serial data 20a received via the video link into image data 30a and control information 30b. The image data 30a and control information 30b correspond to the original image data 10a and control information 10b, respectively, output by the head unit 10. The deserializer 30 outputs the image data 30a and control information 30b obtained by the conversion to the display controller 40.

[0014] The display controller 40 outputs information 40a including image data indicating an image to be displayed on the display 50 to the display 50 based on the image data 30a and control information 30b received from the deserializer 30. The display controller 40 also outputs information 40b for controlling the brightness of the backlight 60 to the backlight 60 based on the image data 30a and the control information 30b. The display controller 40 is an example of an image display control device.

[0015] Although not particularly limited, the image data input to the display controller 40 and the image data output from the display controller 40 include pixel values ​​of red (R) pixels, green (G) pixels, and blue (B) pixels, which represent the RGB color space.

[0016] The display 50 is, for example, a liquid crystal display including a liquid crystal shutter that adjusts the transmittance of light emitted from the backlight 60 and a color filter that receives the light that has passed through the liquid crystal shutter. Note that the display 50 may be a display other than a liquid crystal display as long as it is capable of adjusting the transmittance of light emitted from the backlight 60. The display 50 is an example of a display unit.

[0017] The backlight 60 includes a plurality of LED (Light Emitting Diode) light sources arranged in a matrix, and is arranged facing the surface of the display 50 opposite to the image display surface. Hereinafter, the light irradiation zones corresponding to the respective LED light sources in the display 50 will be referred to as LED zones. Note that the backlight 60 may have a plurality of light sources other than the LED light sources arranged in a matrix.

[0018] For example, the image display system 1 may be installed in a vehicle. In this case, the display device 70 may be used, for example, to display instruments in an instrument cluster or a center information display (CID). Alternatively, the display device 70 may be used in a head-up display that projects an image onto the windshield.

[0019] The image display system 1 to be mounted on a vehicle is designed to meet the requirements of ASIL (Automotive Safety Integrity Level). Note that the image display system 1 equipped with a backlight and having a local dimming function is not limited to being mounted on a vehicle, and may be used in other image display systems such as digital signage.

[0020] For example, the display controller 40 performs local dimming processing to independently adjust the brightness of multiple LED backlights according to the brightness (e.g., pixel value) of an image to be displayed on the display 50. In the local dimming processing, the display controller 40 controls to prevent light leaking around a position opposite a lit LED backlight from increasing the brightness of the surrounding image. The local dimming processing can improve the reproducibility of black in the image displayed on the display 50 while suppressing the power consumption of the backlight 60.

[0021] Fig. 2 is a block diagram showing an example of the display controller 40 of Fig. 1. The display controller 40 is, for example, a semiconductor integrated circuit, and includes a display engine 200, a memory 300, and a processor 400, which are interconnected via a bus 500.

[0022] The display engine 200 includes an image input unit 210, a memory 220, a warping unit 230, an input statistics acquisition unit 240, a local dimming unit 250, an output statistics acquisition unit 260, an image output unit 270, and a register interface 280. The local dimming unit 250 includes a brightness control unit 251 and a pixel compensation unit 252. For example, each element of the display engine 200 operates under control from the processor 400. Although not particularly limited, the display engine 200 processes image data representing an RGB color space.

[0023] The image input unit 210 receives image data (for example, an input image in units of frames) transmitted from the deserializer 30 of FIG. 1 and stores the received image data in the memory 220. The memory 220 is an example of a storage unit that stores image data VIN to be input to the local dimming unit 250. The warping unit 230 uses the image data stored in the memory 220 to perform distortion correction processing to display an undistorted image on the display 50 of FIG. 1. The warping unit 230 outputs the image data with the distortion corrected to the local dimming unit 250.

[0024] The input statistics acquisition unit 240 acquires statistical data of pixel values ​​of a display area including an icon or the like superimposed on an original image in the image data VIN input from the warping unit 230 to the local dimming unit 250. The statistical data acquired by the input statistics acquisition unit 240 is an example of first statistical data. The image data VIN is an example of first image information, and the input statistics acquisition unit 240 is an example of a first statistics acquisition unit. For example, the input statistics acquisition unit 240 receives information indicating a display area including an icon from the deserializer 30 of FIG. 1 or the processor 400 of FIG. 2. Although not particularly limited, when the image display system 1 is used in a vehicle, the icon is, for example, a warning icon that alerts the driver that the road surface is slippery.

[0025] The input statistics acquisition unit 240 outputs the acquired statistical data to the processor 400 via the register interface 280 and the bus 500. The input statistics acquisition unit 240 may have a storage unit such as a buffer that stores statistical data of pixel values. In this case, the statistical data stored in the storage unit may be read out by the processor 400. The input statistics acquisition unit 240 does not acquire statistical data if the image data VIN does not include an icon.

[0026] The brightness control unit 251 of the local dimming unit 250 generates a backlight control signal BLCNT that adjusts the brightness of the backlight 60 of FIG. 1 based on the image data VIN, and outputs the generated backlight control signal BLCNT to the backlight 60. That is, the display controller 40 has a local dimming function. A method for adjusting the brightness of the backlight 60 by the brightness control unit 251 is described with reference to FIG. 4.

[0027] The pixel compensation unit 252 of the local dimming unit 250 corrects pixel values ​​(e.g., luminance values) of the image data VIN based on the luminance of the backlight 60 adjusted by the luminance control unit 251, and outputs the corrected image data VOUT to the image output unit 270. The image data VOUT is an example of second image information. For example, the pixel compensation unit 252 performs correction to relatively decrease pixel values ​​in areas where the luminance of the backlight 60 is high, and relatively increase pixel values ​​in areas where the luminance of the backlight 60 is low. At this time, the pixel compensation unit 252 corrects the pixel values ​​taking into account light leakage to the periphery of each LED light source. The image correction method by the local dimming unit 250 will be described with reference to FIGS. 5 and 6.

[0028] The output statistics acquisition unit 260 acquires statistical data of pixel values ​​of a display area including an icon or the like superimposed on the original image in the image data VOUT output from the local dimming unit 250 to the image output unit 270. The statistical data acquired by the output statistics acquisition unit 260 is an example of second statistical data. The output statistics acquisition unit 260 is an example of a second statistics acquisition unit. For example, the output statistics acquisition unit 260 receives information indicating a display area including an icon from the deserializer 30 in FIG. 1 or the processor 400 in FIG. 2.

[0029] The output statistics acquisition unit 260 outputs the acquired statistical data to the processor 400 via the register interface 280 and the bus 500. The output statistics acquisition unit 260 may have a storage unit such as a buffer that stores statistical data of pixel values. In this case, the statistical data stored in the storage unit may be read out by the processor 400. The output statistics acquisition unit 260 does not acquire statistical data if the image data VC does not include an icon.

[0030] The image output unit 270 transmits the image data VOUT (for example, an output image in units of frames) received from the local dimming unit 250 to the display 50 of FIG.

[0031] The memory 300 stores, for example, an image display control program executed by the processor 400, data used by the image display control program, etc. The processor 400 is a controller such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). For example, the processor 400 controls the operation of the display controller 40 by executing the image display control program.

[0032] Furthermore, the processor 400 detects an abnormality in the local dimming unit 250 (the brightness control unit 251 or the pixel compensation unit 252) based on statistical data acquired by the input statistics acquisition unit 240 and the output statistics acquisition unit 260, for example, by executing an image display control program. In the processor 400, the functional unit that detects an abnormality in the local dimming unit 250 is an example of an abnormality detection unit. Note that the processor 400 can make the detection of an abnormality easier or more difficult based on a threshold value VT received from outside. The threshold value VT may be supplied from outside the image display system 1.

[0033] If the input statistics acquisition unit 240 and the output statistics acquisition unit 260 have not acquired statistical data, the processor 400 does not determine whether there is an abnormality in the local dimming unit 250. The process of detecting an abnormality in the local dimming unit 250 will be described with reference to FIGS. 7 to 10.

[0034] Fig. 3 is a block diagram showing an example of the local dimming unit 250 in Fig. 2. The register interface 280 and bus 500 in Fig. 2 are omitted from Fig. 3. The pixel compensation unit 252 of the local dimming unit 250 has a luminance distribution calculation unit 253, an RGB correction unit 254, and a saturation processing unit 255.

[0035] The luminance distribution calculation unit 253 receives luminance information LINF indicating the luminance of each LED light source and a lighting spread function (LSF), which is a luminance distribution function when only one LED light source is lit. The luminance information LINF is supplied from the luminance control unit 251 and may include information similar to that contained in the backlight control signal BLCNT, or may be the backlight control signal BLCNT itself. The luminance distribution function LSF is supplied, for example, from the memory 300. Based on the luminance information LINF and the luminance distribution function LSF, the luminance distribution calculation unit 253 generates a luminance distribution of the backlight 60 that takes into account light leakage to the surroundings for each LED light source, and outputs the generated luminance distribution to the RGB correction unit 254. For example, the luminance distribution generated by the luminance distribution calculation unit 253 indicates the distribution of luminance of the backlight 60 for each of all pixels of the display 50 and is expressed as a value greater than 0 and equal to or less than 1. Here, the lower the luminance of the luminance distribution, the closer it is to 0, and the higher the luminance, the closer it is to 1.

[0036] The RGB correction unit calculates the gain of the pixel value to be applied to each pixel of the display 50 based on the luminance distribution (luminance value) using equation (1). From equation (1), the minimum value of the gain is 1, and the maximum value of the gain is infinity. Here, infinity is the maximum value that can be expressed by the number of bits representing the gain. Gain=1 / luminance distribution …(1)

[0037] Furthermore, the RGB correction unit 254 uses equations (2-1), (2-2), and (2-3) to calculate the pixel value for each color component of each pixel included in the image data VIN by multiplying the pixel value for each color component by the gain calculated by equation (1). The symbol R in equation (2-1) indicates the pixel value of a red pixel. The symbol G in equation (2-2) indicates the pixel value of a green pixel. The symbol B in equation (2-3) indicates the pixel value of a blue pixel. R = R × Gain …(2-1) G = G × Gain …(2-2) B = B × Gain … (2-3)

[0038] In Fig. 3, the pixel value for each color component of each pixel of the image data VIN is expressed as a normalized value greater than or equal to 0 and less than or equal to 1. For this reason, when the image input unit 210 in Fig. 2 inputs 8-bit (first bit number) image data (0 to 255) for each pixel, the maximum value 255 becomes 1 in the representation of the image data VIN in Fig. 3. The RGB correction unit 254 outputs the calculated pixel value as image data VC to the saturation processing unit 255. The image data VC is an example of internal image information.

[0039] For example, each pixel value of the image data VC is expressed in 12 bits (a second bit number obtained by extending the first bit number), with a minimum value of 0 and a maximum value of 4095. Note that each pixel value of the image data VC may be expressed in a bit number other than 12 bits (for example, 10 bits or 14 bits). Furthermore, when each pixel value of the image data VIN is expressed in 8 bits (0 to 255), each pixel value of the image data VC may be expressed in 20 bits (0 to 1044225 (= 255 × 4095)).

[0040] The saturation processing unit 255 sets the maximum pixel value of the image data VC to 1, and normalizes the other pixel values ​​to be greater than or equal to 0 and less than 1, thereby generating image data VOUT. The saturation processing unit 255 outputs the generated image data VOUT to the display 50. When 8-bit (first bit number) image data (0 to 255) is output for each pixel, similar to the image data VIN, the maximum value 255 becomes 1 in the representation of the image data VOUT in FIG.

[0041] The input statistics acquisition unit 240 acquires statistical data of image data VIN normalized to a range from 0 to 1. The output statistics acquisition unit 260 acquires statistical data of image data VOUT normalized to a range from 0 to 1. This allows the pixel values ​​of the image data VOUT to correspond to the pixel values ​​of the image data VIN before correction of the pixel values. Note that in the local dimming unit 250 of FIG. 3, the image data VC may be output as image data VOUT without saturation processing of the pixel values ​​by the saturation processing unit 255.

[0042] Fig. 4 is a diagram showing an example of controlling the brightness of the backlight 60 by the brightness control unit 251 of Fig. 3. For example, the brightness control unit 251 calculates a maximum value ZMAX of pixel values ​​and an average value ZAVE of pixel values ​​for each region corresponding to an LED zone of the backlight 60 in image data VIN corresponding to an input image. Here, the maximum value ZMAX and the average value ZAVE are calculated from the pixel values ​​of red pixels, green pixels, and blue pixels corresponding to each LED zone.

[0043] Then, the brightness control unit 251 calculates the brightness for each LED zone using equation (3), outputs a backlight control signal BLCNT indicating the calculated brightness to the backlight 60, and outputs brightness information LINF to the pixel compensation unit 252. In equation (3), the symbol α is a parameter for adjusting the brightness and is set to be equal to or greater than 0 and equal to or less than 1. For example, when the parameter α is 0.5, the maximum value ZMAX and the average value ZAVE are mixed at 50% each. Brightness of each LED zone = α × ZMAX + (1-α) × ZAVE … (3)

[0044] Fig. 5 is a diagram showing an example of generating a luminance distribution by the luminance distribution calculation unit 253 of Fig. 3. The luminance distribution calculation unit 253 obtains the luminance distribution by convolving the luminance information LINF for each LED zone of the backlight 60 with the luminance distribution function LSF.

[0045] In the equation shown in Figure 5, the symbol x indicates the horizontal coordinate that identifies the LED zone, and the symbol y indicates the vertical coordinate that identifies the LED zone. bl(x', y') indicates the luminance of each LED zone, and lsf(x-x', y-y') indicates the luminance distribution function LSF. The brackets in Figure 5 show an image of how the luminance distribution is calculated by convolution integral when two LED light sources are turned on and the other LED light sources are turned off.

[0046] Fig. 6 is a diagram showing an example of correcting the luminance of an image by the RGB correction unit 254 of Fig. 3. When image data VIN of an input image is output as image data VOUT without being corrected in accordance with the luminance distribution, the luminance of the image displayed on the display 50 is the product of the luminance of the input image and the luminance of the backlight, and therefore the image is not displayed with the correct luminance.

[0047] 6, the RGB correction unit 254 calculates a gain for each pixel (each of RGB) of the image data VIN using equation (1), and multiplies the pixel value of the image data VIN by the calculated gain to offset the luminance of the backlight 60. This makes it possible to correctly set the luminance of the image displayed on the display 50 using light from the backlight 60, in which the luminance of the LED light source is individually adjusted according to the luminance of the image.

[0048] In the pixel value saturation process by the saturation processor 255 in FIG. 3, the maximum value Vmax of all pixel values ​​included in the image data VC of the corrected image is set to 1, which is the pixel value of the image data VOUT.

[0049] 7 is a diagram showing an example of statistical data acquired by the input statistics acquisition unit 240 and the output statistics acquisition unit 260 in FIG. 3. The input statistics acquisition unit 240 calculates the maximum value MAXin, average value AVEin, and minimum value MINin of pixel values ​​for each pixel color in the icon area, which is a display area including icons included in the image data VIN for each frame. The icon area is an example of a superimposition area.

[0050] Similarly, the output statistics acquisition unit 260 obtains the maximum value MAXout, average value AVEout, and minimum value MINout of pixel values ​​for each pixel color in the icon area, which is a display area including icons included in the image data VC of each frame.

[0051] For the maximum values ​​MAXin and MAXout, the average values ​​AVEin and AVEout, and the minimum values ​​MINin and MINout, the pixel colors are identified by the suffixes r (red), g (green), and b (blue). Figure 7 shows an example of calculation by the input statistics acquisition unit 240 when the icon is two pixels horizontally and two pixels vertically.

[0052] The input statistics acquiring section 240 may acquire at least one of the maximum value MAXin, the average value AVEin, and the minimum value MINin. In this case, the output statistics acquiring section 260 may acquire at least one of the maximum value MAXout, the average value AVEout, and the minimum value MINout corresponding to the statistical data acquired by the input statistics acquiring section 240.

[0053] Fig. 8 is a diagram showing an example of determining an abnormality in local dimming unit 250 by processor 400 of Fig. 3. Processor 400 determines, for each pixel color, whether the deviation between the maximum pixel value of the icon region acquired by input statistics acquisition unit 240 and the maximum pixel value of the icon region acquired by output statistics acquisition unit 260 is between an upper threshold and a lower threshold.

[0054] The processor 400 determines, for each pixel color, whether the deviation between the average pixel value of the icon area acquired by the input statistics acquisition unit 240 and the average pixel value of the icon area acquired by the output statistics acquisition unit 260 is between an upper threshold and a lower threshold.

[0055] The processor 400 determines, for each pixel color, whether the deviation amount between the minimum pixel value of the icon region acquired by the input statistics acquisition unit 240 and the minimum pixel value of the icon region acquired by the output statistics acquisition unit 260 is between an upper threshold and a lower threshold. When the minimum pixel value of the icon region acquired by the input statistics acquisition unit 240 is zero, the processor 400 determines, for each pixel color, whether the minimum pixel value of the icon region acquired by the output statistics acquisition unit 260 is greater than zero.

[0056] Then, when at least one of the deviation amounts is greater than an upper threshold or when at least one of the deviation amounts is smaller than a lower threshold, the processor 400 determines that there is an abnormality in the local dimming unit 250. That is, the processor 400 determines that there is an abnormality in the local dimming unit 250 when the rate of change in the statistical data acquired by the output statistics acquisition unit 260 relative to the statistical data acquired by the input statistics acquisition unit 240 is greater than a predetermined range.

[0057] Furthermore, when the minimum value of the pixel values ​​of the icon region acquired by the input statistics acquisition unit 240 is zero and the minimum value of the pixel values ​​of the icon region acquired by the output statistics acquisition unit 260 is greater than zero, the processor 400 determines that there is an abnormality in the local dimming unit 250. In order to illustrate various deviation amounts, Fig. 8 shows six marks indicating the deviation amounts for each of the maximum value, average value, and minimum value, and two marks indicating the deviation amount when the input statistics acquisition unit 240 acquires a minimum value of 0 for the minimum value.

[0058] The processor 400 determines whether there is an abnormality in the local dimming unit 250 based on the statistical data acquired by the input statistics acquisition unit 240 and the output statistics acquisition unit 260. For this reason, for example, if the input statistics acquisition unit 240 acquires only the maximum value MAXin and the output statistics acquisition unit 260 acquires only the maximum value MAXout, the processor 400 determines whether there is an abnormality in the local dimming unit 250 based only on the maximum value.

[0059] Here, since the image outside the icon area can have various pixel values ​​depending on the content, it may be difficult to set the range for determining an abnormality using the upper and lower thresholds (resulting in a low accuracy of abnormality determination). In contrast, the icons superimposed on the image are known figures to the display controller 40, and the pixel values ​​of the icons themselves are also known. Therefore, by acquiring statistical data from the pixel values ​​of the icon area, it is possible to reduce the content dependency of the pixel values, and it is possible to appropriately set the range for determining an abnormality using the upper and lower thresholds. As a result, it is possible to improve the accuracy of abnormality determination.

[0060] For example, the gain of the icon region is maximum when the pixel values ​​of pixels outside the icon region are minimum (black), so the upper threshold is set in advance to match the maximum value of the gain of the icon region. Also, the gain of the icon region is minimum when the pixel values ​​of pixels outside the icon region are maximum (white), so the lower threshold is set in advance to match the minimum value of the gain. Note that when saturation processing is performed to set the maximum value to 1 after multiplying the pixel value by the gain, the upper threshold becomes the maximum value 1 + the calculation error.

[0061] Furthermore, for example, when the image display system 1 is used for meters on an instrument panel of a vehicle or a center information display, the original image before the icon is superimposed is often a predetermined image. In this case, the upper and lower thresholds may be set according to the actual measured values ​​of the gain using the actual image.

[0062] The input statistics acquisition unit 240 and the output statistics acquisition unit 260 may acquire statistical data using pixel values ​​of an image corresponding to an LED zone including an icon area. The processor 400 may also determine an abnormality in the local dimming unit 250 for each LED zone including an icon area. In this case, the processor 400 may perform an abnormality determination process by treating each LED zone as an icon area.

[0063] Fig. 9 is a flow chart showing an example of processing for determining an abnormality in local dimming unit 250 by processor 400 of Fig. 3. That is, Fig. 9 shows an example of an image display control method by processor 400 and an image display control program executed by processor 400. The flow shown in Fig. 9 starts when image display system 1 or display controller 40 is started. Note that the processing from step S10 to step S70 is performed for each frame.

[0064] First, in step S10, the processor 400 sets an icon area (i.e., an area for acquiring statistical data) which is a display area including an icon superimposed on an original image. The processor 400 may acquire information indicating the icon area from the head unit 10 via the serializer 20 and the deserializer 30 in FIG. 1.

[0065] Next, in step S20, the processor 400 causes the image input unit 210 to acquire frame image data. Next, in step S30, the processor 400 causes the input statistics acquisition unit 240 to acquire statistical data of the icon region included in the image data VIN. Next, in step S40, the processor 400 causes the local dimming unit 250 to perform local dimming processing.

[0066] Next, in step S50, the processor 400 causes the output statistics acquisition unit 260 to acquire statistical data of the icon region included in the image data VOUT. Next, in step S60, the processor 400 determines whether or not there is an abnormality in the local dimming unit 250 based on the statistical data acquired by the input statistics acquisition unit 240 and the statistical data acquired by the output statistics acquisition unit 260. The determination of an abnormality in the local dimming unit 250 is as described with reference to FIG. 8. If the processor 400 determines that there is an abnormality in the local dimming unit 250, the processor 400 proceeds to step S70. If the processor 400 does not determine that there is an abnormality in the local dimming unit 250, the processor 400 returns the process to step S10.

[0067] In step S70, processor 400 determines whether the content of the image displayed on display 50 has been switched. If the content has been switched, processor 400 determines that the content switch has caused the deviation amount of the statistical data to increase, resulting in an abnormality, and returns the process to step S10. If the content has not been switched, processor 400 transitions the process to step S80.

[0068] In step S80, processor 400 performs processing for when an abnormality in local dimming section 250 is detected, and ends the processing shown in Fig. 9. An example of step S80 is shown in Fig. 10.

[0069] When processor 400 determines that content has been switched in step S70, it may return the process to step S10, assuming that local dimming unit 250 is normal, without making the abnormality determination in step S60, for at least one frame period. Furthermore, when image display system 1 or display controller 40 is started up, processor 400 may return the process to step S10, assuming that local dimming unit 250 is normal, without making the abnormality determination in step S60, for at least one frame period. This makes it possible to prevent an abnormality in local dimming unit 250 from being erroneously detected due to image disturbances or the like when content is switched.

[0070] Fig. 10 is a flow diagram showing an example of the processing of step S80 in Fig. 9. First, in step S81, the processor 400 stops the pixel value correction operation by the pixel compensation unit 252. Then, the processor 400 causes the image data VIN to be output to the display 50 as image data VOUT, regardless of the operation of the pixel compensation unit 252.

[0071] Next, in step S82, the processor 400 turns on all the LED light sources of the backlight 60 and sets the backlight 60 to a preset brightness. That is, the processor 400 turns on all the LED light sources at a predetermined brightness, regardless of the operation of the brightness control unit 251.

[0072] This prevents an image with an abnormal pixel value from being displayed on the display 50 due to a malfunction of the pixel compensation unit 252 when an abnormality is determined in the local dimming unit 250. Furthermore, when an abnormality is determined in the local dimming unit 250, it prevents the LED light source from being turned on at an incorrect brightness due to an incorrect backlight control signal BLCNT from the brightness control unit 251. Note that the processor 400 may stop the operation of the input statistics acquisition unit 240 and the output statistics acquisition unit 260 when an abnormality in the local dimming unit 250 is detected.

[0073] Next, in step S83, processor 400 determines whether or not display of an icon indicating an abnormality in local dimming unit 250 is permitted. If display of an icon indicating an abnormality is permitted, processor 400 proceeds to step S84. If display of an icon indicating an abnormality is not permitted, processor 400 ends the process shown in FIG.

[0074] In step S84, the processor 400 causes an icon indicating an abnormality to be displayed on the display 50, and ends the processing shown in Fig. 10. In step S84, the processor 400 may directly control the display 50 and cause the icon indicating an abnormality to be displayed using an OSD (On Screen Display) of the display 50. Alternatively, the processor 400 may cause the icon indicating an abnormality to be displayed on the display 50 by inputting image data indicating the icon to the image input unit 210, or by overwriting the icon data in an area of ​​the memory 220 that stores image data.

[0075] As described above, in this embodiment, it is possible to determine an abnormality in the local dimming unit 250 that has not been detected in the past, based on the amount of deviation in statistical data between image data VIN input to the pixel compensation unit 252 and image data VOUT output from the pixel compensation unit 252. By acquiring statistical data from pixel values ​​of superimposed images such as icons whose pixel values ​​are known, it is possible to reduce the content dependency of pixel values ​​and appropriately set the criteria for determining an abnormality. For example, it is possible to appropriately set the range for determining an abnormality using an upper threshold and a lower threshold. As a result, it is possible to improve the accuracy of determining an abnormality in the local dimming unit 250.

[0076] By acquiring multiple types of statistical data such as the maximum, average, and minimum pixel values, the criteria for determining whether the local dimming unit 250 is abnormal can be made stricter, and the reliability of the display controller 40 can be improved.

[0077] When switching content or starting up the display controller 40, etc., the determination of an abnormality in the local dimming unit 250 is not performed for at least one frame period. This makes it possible to prevent an abnormality in the local dimming unit 250 from being mistakenly detected due to image disturbances or the like when switching content or starting up.

[0078] When an abnormality in the local dimming unit 250 is detected, the pixel value correction operation by the pixel compensation unit 252 is stopped, thereby preventing an image with abnormal pixel values ​​from being displayed on the display 50 due to a malfunction of the pixel compensation unit 252. Furthermore, when an abnormality in the local dimming unit 250 is detected, all of the LED light sources of the backlight 60 are turned on, thereby preventing the LED light sources from being turned on due to an erroneous backlight control signal BLCNT from the brightness control unit 251.

[0079] (Second embodiment) Fig. 11 is a diagram showing an example of the operation of the processor 400 included in the display controller 40 in the image display system of the second embodiment. The image display system equipped with the display controller 40 including the processor 400 that performs the operation shown in Fig. 11 has the same configuration and functions as the image display system 1 shown in Fig. 1. Elements similar to those described in Figs. 1 to 10 are given the same reference numerals, and detailed description thereof will be omitted.

[0080] The statistical data acquired by the input statistics acquisition unit 240 and the output statistics acquisition unit 260 is the same as that in Fig. 7. The method by which the processor 400 determines whether or not there is an abnormality in the local dimming unit 250 is the same as that in Fig. 8. The processing performed when an abnormality in the local dimming unit 250 is determined is the same as that in Fig. 10.

[0081] For simplicity of explanation, Fig. 11 shows an example in which the icon area and the LED zone coincide with each other and the backlight 60 has six LED light sources. Fig. 11(a) shows a case in which the image (background) displayed on the display 50 of Fig. 1 is dark. Fig. 11(b) shows a case in which the image (background) displayed on the display 50 is bright.

[0082] 3 decreases the brightness of the backlight 60 as the image becomes darker, and increases the brightness of the backlight 60 as the image becomes brighter. Therefore, the brightness of the LED zone corresponding to the icon area when the background is dark is lower than the brightness of the LED zone corresponding to the icon area when the background is bright.

[0083] Therefore, depending on the brightness of the background, the gain calculated by the RGB correction unit 254 in Fig. 3 changes, and the brightness of the icon changes. In this case, it is necessary to narrow the area between the upper and lower thresholds shown in Fig. 8 and widen the range in which an abnormality in the local dimming unit 250 is determined. If the area between the upper and lower thresholds is narrowed, there is a possibility that the local dimming unit 250 may be determined to be abnormal even when it is not abnormal.

[0084] Therefore, processor 400 fixes the brightness of the LED zone including the icon. This allows the brightness distribution of the icon area corresponding to the icon to be the same regardless of the brightness of the background. As a result, it is not necessary to narrow the area between the upper and lower thresholds, and therefore it is possible to correctly determine whether local dimming unit 250 is malfunctioning.

[0085] Fig. 12 is a flow chart showing an example of processing by the processor 400 that performs the operation of Fig. 11 to determine an abnormality in the local dimming unit 250. The configuration and function of the display controller 40 that performs the processing of Fig. 12 are similar to the configuration and function of the display controller 40 shown in Figs. 2 and 3, respectively, except that the processing executed by the processor 400 is different.

[0086] In this embodiment, processor 400 performs the process of step S12 between steps S10 and S20 in Fig. 9 in the process of determining an abnormality in local dimming unit 250. The processes of step S10 and steps S20 to S80 are the same as those in Fig. 9. In step S12, processor 400 causes brightness control unit 251 in Fig. 3 to fix the brightness of the LED zone corresponding to the icon area including the icon, and then performs the process of step S20. This makes it possible to make the brightness distribution of the icon area corresponding to the icon the same regardless of the brightness of the background, as described in Fig. 11.

[0087] Processor 400 may not need to determine whether there is an abnormality in step S60 for at least one frame period when switching content, starting up image display system 1, or starting up display controller 40. In this case, local dimming unit 250 is determined to be normal, and the process returns to step S10.

[0088] As described above, this embodiment can also achieve the same effects as the above-described embodiments. For example, an abnormality in the local dimming unit 250 can be determined based on the amount of deviation in statistical data between the image data VIN and the image data VOUT. In this case, by acquiring statistical data from pixel values ​​of an overlaid image such as an icon, the content dependency of pixel values ​​can be reduced, and the criteria for determining an abnormality can be set appropriately. As a result, the accuracy of determining an abnormality in the local dimming unit 250 can be improved. When an abnormality in the local dimming unit 250 is detected, an image with abnormal pixel values ​​can be prevented from being displayed on the display 50, and the LED light source can be prevented from being turned on by an erroneous backlight control signal BLCNT.

[0089] Furthermore, in this embodiment, by fixing the brightness of the LED zone including the icon, the brightness distribution of the icon area corresponding to the icon can be made the same regardless of the brightness of the background. As a result, the area between the upper and lower thresholds does not need to be narrowed, and an abnormality in the local dimming unit 250 can be correctly determined.

[0090] (Third embodiment) Fig. 13 is a diagram showing an example of the operation of the processor 400 mounted on the display controller 40 in the image display system of the third embodiment. The image display system mounted with the display controller 40 including the processor 400 that performs the operation shown in Fig. 13 has the same configuration and functions as the image display system 1 shown in Fig. 1. Elements similar to those described in Figs. 1 to 10 are given the same reference numerals, and detailed description thereof will be omitted.

[0091] The statistical data acquired by the input statistics acquisition unit 240 and the output statistics acquisition unit 260 is the same as that in Fig. 7. The method by which the processor 400 determines whether or not there is an abnormality in the local dimming unit 250 is the same as that in Fig. 8. The processing performed when an abnormality in the local dimming unit 250 is determined is the same as that in Fig. 10.

[0092] In this embodiment, the input statistics acquisition unit 240 and the output statistics acquisition unit 260 acquire statistical data using pixel values ​​of images corresponding to LED zones including the icon area, and the processor 400 determines whether there is an abnormality in the local dimming unit 250 for each LED zone including the icon area.

[0093] For simplicity of explanation, FIG. 13 also shows an example in which the backlight 60 has six LED light sources. FIG. 13(a) shows a case in which the size of an icon in an image received by the image input unit 210 is equal to or smaller than the size of an LED zone. In this case, the processor 400 places the icon in a position that does not cross an LED zone and is closest to the original icon position. The processor 400 also sets the LED zone including the icon to the icon area. As a result, the input statistics acquisition unit 240 and the output statistics acquisition unit 260 acquire statistical data using pixel values ​​of the image corresponding to the LED zone including the icon. In the processor 400, the functional unit that places the icon in a position that does not cross an LED zone and sets the LED zone including the icon to the icon area is an example of an overlap area setting unit.

[0094] 13(b) shows a case where the size of the icon is larger than the size of the LED zone in the image received by the image input unit 210. In this case, the processor 400 sets, for example, the LED zone that includes the most pixels of the icon as the icon area. In the processor 400, the functional unit that sets the LED zone that includes the most pixels of the icon as the icon area is an example of a superimposition area setting unit.

[0095] When statistical data is acquired for each LED zone and an abnormality in the local dimming unit 250 is determined, the proportion of icons included in the icon area corresponding to the LED zone decreases depending on the position of the icon. As a result, if the statistical data becomes more susceptible to the influence of the background image, the accuracy of determining an abnormality in the local dimming unit 250 decreases. In this embodiment, for example, the proportion of icons included in the icon area can be increased by moving the icons. As a result, the statistical data can be made less susceptible to the influence of the background image, and a decrease in the accuracy of determining an abnormality in the local dimming unit 250 can be suppressed.

[0096] Fig. 14 is a flow chart showing an example of processing by processor 400 performing the operation of Fig. 13 to determine an abnormality in local dimming unit 250. The configuration and function of display controller 40 performing the processing of Fig. 14 are similar to the configuration and function of display controller 40 shown in Fig. 2 and Fig. 3, respectively, except that the processing executed by processor 400 is different.

[0097] In this embodiment, the processor 400 performs the process of step S14 instead of step S10 in Fig. 9 in the process of determining an abnormality in the local dimming unit 250. As in Fig. 9, the processes of steps S14 and S20 to S70 are performed for each frame. The processes of steps S20 to S80 are the same as those in Fig. 9. In step S14, the processor 400 sets an icon region for acquiring statistical data, and proceeds to step S20. An example of the process of step S14 is shown in Fig. 15.

[0098] It should be noted that processor 400 may not need to determine whether there is an abnormality in step S60 for at least one frame period when switching content, starting up image display system 1, or starting up display controller 40. In this case, it is determined that local dimming unit 250 is normal, and the process returns to step S14.

[0099] Fig. 15 is a flow diagram showing an example of the process of step S14 in Fig. 14. First, in step S141, the processor 400 determines whether or not the icon is located at a position that straddles LED zones. If the icon is located at a position that straddles LED zones, the processor 400 shifts the process to step S142. If the icon is not located at a position that straddles LED zones, that is, if the icon is included in only one LED zone, the processor 400 ends the process shown in Fig. 15.

[0100] In step S142, the processor 400 determines whether the size of the icon is equal to or smaller than the size of the LED zone. If the size of the icon is equal to or smaller than the size of the LED zone, the processor 400 shifts the process to step S143. If the size of the icon is larger than the size of the LED zone, the processor 400 shifts the process to step S144.

[0101] In step S143, the processor 400 moves the icon to a position that does not straddle an LED zone, and ends the processing shown in Fig. 15. For example, the processor 400 may move the icon to an LED zone that includes the most pixels of the icon, or may move the icon to an LED zone that includes the center of the icon.

[0102] At step S144, the processor 400 sets, for example, the LED zone that includes the most pixels of the icon as the icon region that includes the icon, and ends the process shown in FIG.

[0103] As described above, this embodiment can also achieve the same effects as the above-described embodiments. For example, an abnormality in the local dimming unit 250 can be determined based on the amount of deviation in statistical data between the image data VIN and the image data VOUT. In this case, by acquiring statistical data from pixel values ​​of an overlaid image such as an icon, the content dependency of pixel values ​​can be reduced, and the criteria for determining an abnormality can be set appropriately. As a result, the accuracy of determining an abnormality in the local dimming unit 250 can be improved. When an abnormality in the local dimming unit 250 is detected, an image with abnormal pixel values ​​can be prevented from being displayed on the display 50, and the LED light source can be prevented from being turned on by an erroneous backlight control signal BLCNT.

[0104] Furthermore, in this embodiment, by increasing the proportion of icons included in the icon area, the statistical data can be made less susceptible to the influence of the background image, which can prevent a decrease in the accuracy of determining abnormalities in the local dimming unit 250.

[0105] (Fourth embodiment) Fig. 16 is a block diagram showing an example of a display controller 40A mounted on an image display system according to the fourth embodiment. The image display system mounted with the display controller 40A shown in Fig. 16 has the same configuration and functions as the image display system 1 shown in Fig. 1. Elements similar to those described in Figs. 1 to 10 are given the same reference numerals, and detailed description thereof will be omitted. The processing performed when an abnormality in the local dimming unit 250 is determined is the same as that in Fig. 10.

[0106] A display controller 40A shown in Fig. 16 has a display engine 200A instead of the display engine 200 in Fig. 2. In Fig. 16, the display engine 200A has a local dimming section 250A instead of the local dimming section 250 in Fig. 2.

[0107] Local dimming unit 250A has a pixel compensation unit 252A instead of pixel compensation unit 252 in Fig. 2. Other configurations and functions of display controller 40A and display engine 200A are similar to those of display controller 40 and display engine 200 in Fig. 2. Pixel compensation unit 252A has the same configuration and function as pixel compensation unit 252 in Fig. 3, except that an internal statistics acquisition unit 256A is added.

[0108] FIG. 17 is a block diagram showing an example of the local dimming unit 250A of FIG. 16. Elements similar to those of the local dimming unit 250 of FIG. 3 are assigned the same reference numerals, and detailed description thereof will be omitted. In the pixel compensation unit 252A, the internal statistics acquisition unit 256A acquires statistical data of pixel values ​​of all pixels for one frame included in the image data VC output from the RGB correction unit 254. That is, the internal statistics acquisition unit 256 acquires statistical data of pixel values ​​included in the image data VC generated by the pixel compensation unit 252A in the process of generating image data VOUT from the image data VIN. The statistical data acquired by the internal statistics acquisition unit 256 is an example of internal statistical data. A method for acquiring statistical data by the internal statistics acquisition unit 256 will be described with reference to FIG. 18.

[0109] FIG. 18 is a diagram showing an example of statistical data acquired by the internal statistics acquisition unit 256A of FIG. 17. The internal statistics acquisition unit 256A acquires statistical data of pixel values ​​of all pixels of each frame included in the image data VC. For example, the internal statistics acquisition unit 256A calculates the maximum value MAX of the pixel values ​​of all pixels, the average value AVE1 of pixel values ​​greater than 1 for all pixels, and the ratio RT1 of pixels greater than 1 to all pixels. Note that, as shown in FIG. 17, each pixel value of the image data VC has a minimum value of 0 and a maximum value of 4095. A pixel value of 1 in the image data VC is an example of a first pixel value.

[0110] 17, as in Fig. 3, the pixel values ​​for each color component of each pixel of the image data VIN and image data VOUT are expressed as values ​​normalized to be greater than or equal to 0 and less than 1. For this reason, when the image input unit 210 in Fig. 16 inputs 8-bit (first bit number) image data (0 to 255) for each pixel, the maximum value 255 becomes 1 in the representation of the image data VIN in Fig. 17. Also, when 8-bit (first bit number) image data (0 to 255) for each pixel is output, the maximum value 255 becomes 1 in the representation of the image data VOUT in Fig. 17.

[0111] Fig. 18 shows an example of calculations by the internal statistics acquisition unit 256A when the display 50 has two pixels horizontally and two pixels vertically. In the example shown in Fig. 18, the internal statistics acquisition unit 256A acquires a maximum value MAX=1.4, an average value AVE1=1.3, and a ratio RT1=50%.

[0112] The processor 400 compares the maximum value MAX, average value AVE1, and ratio RT1 acquired by the internal statistics acquisition unit 256A with a first threshold value VT1, a second threshold value VT2, and a third threshold value VT3, respectively. Then, if at least one of (Condition 1), (Condition 2), and (Condition 3) is met, the processor 400 determines that an abnormality has occurred in the local dimming unit 250. (Condition 1) Maximum value MAX > First threshold value VT1 (Condition 2) Average value AVE1 > second threshold VT2 (Condition 3) Ratio RT1 > Third Threshold VT3

[0113] The pixel value obtained from the gain calculated by the RGB correction unit 254 is usually in a predetermined range of 0 or more, which is narrower than the range of 0 to 4095 that can be expressed as image data VC. For this reason, if the maximum value MAX is larger than the first threshold value VT1 that corresponds to the predetermined range, it is considered that there is some kind of abnormality in the local dimming unit 250.

[0114] Similarly, the average pixel value of all pixels calculated from the gain calculated by the RGB correction unit 254 is usually 1 or less. Therefore, if the average value AVE1 is greater than the second threshold value VT2, it is considered that there is some kind of abnormality in the local dimming unit 250. Furthermore, the proportion RT1 of pixels with pixel values ​​greater than 1 to all pixels is usually less than a predetermined third threshold value VT3. Therefore, if the proportion RT1 is greater than the third threshold value VT3, it is considered that there is some kind of abnormality in the local dimming unit 250.

[0115] In this embodiment, the processor 400 determines whether there is an abnormality in the local dimming unit 250 based on statistical data acquired from the pixel values ​​of all pixels in the image data VC. Therefore, the processor 400 can determine whether there is an abnormality in the local dimming unit 250 based not only on the pixel values ​​of areas where there are icons but also on the pixel values ​​of areas where there are no icons. Note that, for example, the processor 400 may determine whether there is an abnormality in the local dimming unit 250 on an LED zone basis.

[0116] Fig. 19 is a flow chart showing an example of processing for determining an abnormality in local dimming unit 250A by processor 400 of Fig. 17. That is, Fig. 19 shows an example of an image display control method by processor 400 and an image display control program executed by processor 400. The flow shown in Fig. 19 starts when image display system 1 or display controller 40 is started.

[0117] As in Fig. 9, the processes of steps S10 to S70 are performed for each frame. The processes of steps S10, S20, S40, S70, and S80 are the same as the processes of steps S10, S20, S40, S70, and S80 in Fig. 9. After step S20, processor 400 performs step S40, and after step S40, performs step S52 instead of step S50 in Fig. 9.

[0118] In step S52, the internal statistics acquisition unit 256A acquires statistical data of pixel values ​​of all pixels in one frame of image data VC. Next, in step S62, the processor 400 determines whether or not there is an abnormal value in the statistical data based on the above-mentioned (Condition 1), (Condition 2), and (Condition 3). If there is an abnormal value in the statistical data, the processor 400 shifts the process to step S70. If there is no abnormal value in the statistical data, the processor 400 returns the process to step S10.

[0119] Processor 400 may not need to determine whether there is an abnormality in step S62 for at least one frame period when switching content, starting up image display system 1, or starting up display controller 40. In this case, local dimming unit 250 is determined to be normal, and the process returns to step S10.

[0120] 20 is a diagram showing an example of a frame image used to determine whether there is an abnormality in the local dimming unit 250. As described above, the processor 400 determines whether there is an abnormality in the local dimming unit 250 based on statistical data acquired from the pixel values ​​of all pixels of the image data VC. Therefore, the processor 400 can determine whether there is an abnormality in the local dimming unit 250 not only for LED zones with icons but also for LED zones without icons.

[0121] As described above, this embodiment can also achieve the same effects as the above-described embodiments. Furthermore, in this embodiment, an abnormality in the local dimming unit 250 can be determined based on statistical data (an example of internal statistical data) acquired from pixel values ​​of image data VC generated inside the pixel compensation unit 252A. In this case, an abnormality in the local dimming unit 250 can be determined based not only on pixel values ​​in areas where icons are present, but also on pixel values ​​in areas where no icons are present. As a result, an abnormality in the local dimming unit 250 can be determined based on statistical data of pixel values ​​of images corresponding to all LED zones.

[0122] The internal statistics acquisition unit 256A acquires multiple types of statistical data, such as the maximum pixel value MAX, the average pixel value AVE1 greater than 1, and the ratio RT1 of pixels greater than 1 to all pixels. The processor 400 compares the maximum pixel value MAX, the average pixel value AVE1, and the ratio RT1 with a first threshold value VT1, a second threshold value VT2, and a third threshold value VT3, respectively. This makes it possible to tighten the criteria for determining whether the local dimming unit 250 is abnormal, thereby improving the reliability of the display controller 40.

[0123] (Fifth embodiment) Fig. 21 is a block diagram showing an example of a display controller 40B mounted on an image display system according to the fifth embodiment. The image display system mounted with the display controller 40B shown in Fig. 21 has the same configuration and functions as the image display system 1 shown in Fig. 1. Elements similar to those described in Figs. 1 to 10 are given the same reference numerals, and detailed description thereof will be omitted. Elements similar to those in the display controller 40 of Fig. 2 are given the same reference numerals as those in Fig. 2.

[0124] A display controller 40B shown in FIG. 21 has a display engine 200B instead of the display engine 200 of FIG. 2. The display engine 200B has a local dimming unit 250A of FIG. 17 instead of the local dimming unit 250 of FIG. 2. That is, the display engine 200B has an internal statistics acquisition unit 256A in addition to the input statistics acquisition unit 240 and the output statistics acquisition unit 260 of FIG. 2. Other configurations and functions of the display controller 40A and the display engine 200A are similar to those of the display controller 40 and the display engine 200 of FIG. 2, respectively.

[0125] For example, the processor 400 determines whether there is an abnormality in the local dimming unit 250A based on statistical data acquired by the input statistics acquisition unit 240, the output statistics acquisition unit 260, and the internal statistics acquisition unit 256A. Note that the processor 400 may determine whether there is an abnormality in the local dimming unit 250A based on either the statistical data acquired by the input statistics acquisition unit 240 and the output statistics acquisition unit 260, or the statistical data acquired by the internal statistics acquisition unit 256A, depending on the operation mode.

[0126] When the statistical data falls outside any of the reference values ​​(the range for determining an abnormality based on the upper and lower thresholds, the first threshold VT1, the second threshold VT2, or the third threshold VT3 described above), the processor 400 determines that an abnormality exists in the local dimming unit 250. This makes it possible to further tighten the criteria for determining an abnormality in the local dimming unit 250, thereby further improving the reliability of the display controller 40.

[0127] As described above, this embodiment can also achieve the same effects as the above-described embodiment. Furthermore, this embodiment can further tighten the criteria for determining whether or not an abnormality has occurred in the local dimming unit 250, thereby further improving the reliability of the display controller 40. Furthermore, by switching the operating mode, an appropriate determination method can be selected from among multiple types of abnormality determination methods.

[0128] Although the present invention has been described above based on the embodiments, the present invention is not limited to the requirements shown in the above embodiments. These requirements can be changed without departing from the spirit of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0129] 1 Image display system 10 Head Unit 20 Serializers 30 Deserializer 40, 40A, 40B Display Controller 50 displays 60 Backlight 200, 200A, 200B Display Engine 210 Image input unit 220 memory 230 Warping Section 240 Input statistics acquisition unit 250, 250A local dimming unit 251 Brightness control section 252, 252A pixel compensation unit 253 Luminance distribution calculation unit 254 RGB correction section 255 saturation processor 256A Internal statistics acquisition section 260 Output statistics acquisition unit 270 Image output unit 280 Register Interface 300 memory 400 processors 500 Bus BLCNT Backlight control signal LINF luminance information LSF Luminance Distribution Function VC, VIN, VOUT image data

Claims

1. An image display control device having a local dimming function, a brightness control unit that controls brightness of a plurality of light sources included in the backlight based on first image information that indicates an image to be displayed on the display unit; a pixel compensation unit that corrects pixel values ​​included in the first image information based on the luminance of the plurality of light sources to generate second image information; a first statistics acquisition unit that acquires first statistical data of pixel values ​​included in the first image information; a second statistics acquisition unit that acquires second statistical data of pixel values ​​included in the second image information; an abnormality detection unit that detects an abnormality in the luminance control unit or the pixel compensation unit based on a deviation amount of the second statistical data from the first statistical data; An image display control device having the above configuration.

2. the image to be displayed on the display unit includes an original image and a superimposed image to be superimposed on the original image, the first statistics acquisition unit acquires the first statistical data of a superimposed area including the superimposed image from the first image information; The second statistics acquisition unit acquires the second statistical data of a superimposed area including the superimposed image from the second image information. The image display control device according to claim 1 .

3. The luminance control unit fixes the luminance of a light source corresponding to the overlapping region among the plurality of light sources. The image display control device according to claim 2 .

4. and a superimposition area setting unit that, when the superimposed image is smaller than the illumination zone of each of the plurality of light sources, arranges the superimposed image at a position that does not straddle the illumination zone, and sets the illumination zone including the superimposed image as the superimposed area. The image display control device according to claim 2 .

5. and a superimposition area setting unit that sets the irradiation zone that includes the most pixels of the superimposition image as the superimposition area when the superimposition image is larger than the irradiation zone of each of the plurality of light sources. The image display control device according to claim 2 .

6. the first statistical data is at least one of a maximum value, an average value, and a minimum value of pixel values ​​included in the first image information, The second statistical data is at least one of a maximum value, an average value, and a minimum value of pixel values ​​included in the second image information, which corresponds to the first statistical data.

5. The image display control device according to claim 1.

7. The abnormality detection unit detects an abnormality in the brightness control unit or the pixel compensation unit when a rate of change in the second statistical data relative to the first statistical data is greater than a predetermined range. The image display control device according to any one of claims 1 to 6.

8. An image display control device having a local dimming function, a brightness control unit that controls brightness of a plurality of light sources included in the backlight based on first image information that indicates an image to be displayed on the display unit; a pixel compensation unit that corrects pixel values ​​included in the first image information based on the luminance of the plurality of light sources to generate second image information; an internal statistics acquisition unit that acquires internal statistical data of pixel values ​​included in internal image information generated by the pixel compensation unit in the process of generating the second image information from the first image information; an abnormality detection unit that detects an abnormality in the luminance control unit or the pixel compensation unit based on the internal statistical data; An image display control device having the above configuration.

9. the pixel compensation unit corrects pixel values ​​included in the first image information based on the luminance of the plurality of light sources, and generates the internal image information expressed by a second bit number obtained by expanding a first bit number representing the first image information; The internal statistical data is at least one of the maximum value of pixel values ​​included in the internal image information, the average value of pixel values ​​included in the internal image information that are greater than a first pixel value, and the ratio of pixels whose pixel values ​​are greater than the first pixel value to all pixels. The image display control device according to claim 8.

10. The abnormality detection unit detects an abnormality in the brightness control unit or the pixel compensation unit when the maximum value is greater than a first threshold value, when the average value is greater than a second threshold value, or when the ratio is greater than a third threshold value. The image display control device according to claim 9.

11. The abnormality detection unit inhibits the abnormality detection process for at least one frame period when the content of the image to be displayed on the display unit is switched or when the image display control device is started. The image display control device according to any one of claims 1 to 10.

12. When the abnormality detection unit detects the abnormality, the first image information is output as the second image information regardless of the operation of the pixel compensation unit, and the plurality of light sources are turned on regardless of the operation of the brightness control unit. The image display control device according to any one of claims 1 to 11.

13. An image display control device having a display engine that performs local dimming processing and a processor that controls the operation of the display engine, The display engine includes: inputting first image information indicating an image to be displayed on the display unit; holding the first image information; controlling the luminance of a plurality of light sources included in the backlight based on the first image information; correcting pixel values ​​included in the first image information based on the luminance of the plurality of light sources to generate second image information; obtaining first statistical data of pixel values ​​included in the first image information; obtaining second statistical data of pixel values ​​included in the second image information; outputting the second image information to the display unit; The processor detects an abnormality in the local dimming process based on a deviation amount of the second statistical data from the first statistical data. Image display control device.

14. An image display control device having a display engine that performs local dimming processing and a processor that controls the operation of the display engine, The display engine includes: inputting first image information indicating an image to be displayed on the display unit; holding the first image information; controlling the luminance of a plurality of light sources included in the backlight based on the first image information; correcting pixel values ​​included in the first image information based on the luminance of the plurality of light sources to generate second image information; acquiring internal statistical data of pixel values ​​included in internal image information generated in the process of generating the second image information from the first image information; outputting the second image information to the display unit; The processor detects an abnormality in the local dimming process based on the internal statistical data. Image display control device.

15. The image display control device according to any one of claims 1 to 14, The display unit; the backlight disposed opposite the display unit; a head unit that generates the image and outputs the first image information indicating the generated image to the image display control device; An image display system having:

16. An image display control method using an image display control device having a local dimming function, comprising: a brightness control unit included in the image display control device, which controls brightness of a plurality of light sources included in the backlight based on first image information indicating an image to be displayed on a display unit; a pixel compensation unit included in the image display control device corrects pixel values ​​included in the first image information based on the luminance of the plurality of light sources to generate second image information; a first statistical acquisition unit included in the image display control device acquires first statistical data of pixel values ​​included in the first image information; a second statistical acquisition unit included in the image display control device acquires second statistical data of pixel values ​​included in the second image information; An abnormality detection unit included in the image display control device detects an abnormality in the brightness control unit or the pixel compensation unit based on the amount of deviation of the second statistical data from the first statistical data. Image display control method.

17. An image display control method using an image display control device having a local dimming function, comprising: a brightness control unit included in the image display control device, which controls brightness of a plurality of light sources included in the backlight based on first image information indicating an image to be displayed on a display unit; a pixel compensation unit included in the image display control device corrects pixel values ​​included in the first image information based on the luminance of the plurality of light sources to generate second image information; an internal statistics acquisition unit of the image display control device acquires internal statistical data of pixel values ​​included in internal image information generated by the pixel compensation unit in the process of generating the second image information from the first image information; An abnormality detection unit included in the image display control device detects an abnormality in the brightness control unit or the pixel compensation unit based on the internal statistical data. Image display control method.

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