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

Abstract

This image display control device comprises a brightness control unit that generates backlight control information to be used for controlling a plurality of light sources, a pixel compensation unit that corrects an input image on the basis of the backlight control information, and an abnormality detection unit. The abnormality detection unit detects an abnormality of the brightness control unit according to whether or not second statistical data of the brightness values of respective light sources contained in the backlight control information falls within a range between an upper limit value and a lower limit value determined by first statistical data of pixel values contained in first image information representing the input image. This enables detection of an abnormality of the brightness control unit installed in an image display control device having a local dimming feature.

Description

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

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

[0002] Recently, local dimming has become known in image display control devices that display images on a display device with a backlight in which multiple light sources are arranged in an array, and that adjusts the luminance of each light source according to the luminance of the input image. Local dimming makes it possible to reduce power consumption while improving the contrast ratio.

[0003] A backlight unit is known that includes a plurality of LED elements whose light emission amounts can be independently controlled and a plurality of optical sensors that detect the light emission brightness of each LED element. In this type of backlight unit, if one of the optical sensors fails, another optical sensor is used in place of the failed optical sensor to estimate the brightness of the LED element corresponding to the failed optical sensor (see, for example, Patent Document 1).

[0004] When one of the multiple light-emitting areas included in the light source for illuminating the liquid crystal panel fails, a method is known in which the image in the display area corresponding to the failed light-emitting area is moved to the display area corresponding to the normal light-emitting area (see, for example, Patent Document 2).

[0005] JP 2014-182291 A JP 2018-159796 A

[0006] For example, an image display control device that performs local dimming includes a brightness control unit that adjusts the brightness of multiple light sources according to the brightness of an input image, and a pixel compensation unit that adjusts the brightness of the image according to the adjusted brightness of the light sources. If an abnormality occurs in the brightness control unit, the brightness or color of the image displayed on the display device may change.

[0007] For example, some abnormalities in the brightness control unit can be detected by a CRC (Cyclic Redundancy Check) check, which detects abnormalities in communication between the brightness control unit and the driver that drives the light source. However, for example, when an image (video) is displayed with each light source emitting light instead of being turned off, it is difficult to confirm whether the brightness output value from the brightness control unit to the driver is normal. For example, an abnormality in the brightness output value can be determined by implementing identical circuits in parallel and comparing the two outputs. However, this increases the circuit size and the cost of the image display control device.

[0008] The present invention has been made in consideration of the above points, and aims to detect an abnormality in a brightness control unit that controls the brightness of multiple light sources and is installed in an image display control device having a local dimming function.

[0009] 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 generates backlight control information used to control multiple light sources included in a backlight based on first image information representing an input image; 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 representing an output image; 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 the brightness values ​​of each light source included in the backlight control information; and an abnormality detection unit that detects an abnormality in the brightness control unit depending on whether the second statistical data is within a range between an upper limit value and a lower limit value determined by the first statistical data.

[0010] According to the disclosed technology, it is possible to detect an abnormality in a brightness control unit that controls the brightness of a plurality of light sources and is installed in an image display control device having a local dimming function.

[0011] 11 is a block diagram showing an example of an image display system according to a first embodiment. FIG. 12 is a block diagram showing an example of a display controller of FIG. 1. FIG. 13 is a block diagram showing an example of a local dimming unit of FIG. 2. FIG. 14 is a diagram showing an example of controlling the luminance of a backlight by the luminance control unit of FIG. 3. FIG. 15 is a diagram showing an example of generating a luminance distribution by the luminance distribution calculation unit of FIG. 3. FIG. 16 is a diagram showing an example of correcting the luminance of an image by the RGB correction unit of FIG. 3. FIG. 17 is a diagram showing an example of statistical information acquired by the input color statistics acquisition unit and the output luminance statistics acquisition unit of FIG. 3. FIG. 18 is a diagram showing an example of thresholds used to determine an abnormality in the luminance control unit of FIG. 3. FIG. 19 is a flow chart showing an example of processing for determining an abnormality in the luminance control unit by the processor of FIG. 3. FIG. 19 is a flow chart showing an example of processing of step S80 of FIG. 9. FIG. 11 is a block diagram showing an example of a display controller according to a second embodiment. FIG. 12 is a block diagram showing an example of an input color statistics acquisition unit, an output luminance statistics acquisition unit, and an output color statistics acquisition unit connected to the local dimming unit of FIG. 11. FIG. 13 is a diagram showing an example of statistical data acquired by the input color statistics acquisition unit, the output luminance statistics acquisition unit, and the output color statistics acquisition unit of FIG. 12. FIG. 14 is a diagram showing an example of thresholds used to determine an abnormality in the luminance control unit of FIG. 12. FIG. 15 is a flow chart showing an example of processing for determining an abnormality in the luminance control unit by the processor of FIG. 12.

[0012] Hereinafter, embodiments will be described with reference to the drawings. In the following description, image data may be simply referred to as an image.

[0013] 1 is a block diagram showing an example of an image display system according to Embodiment 1. 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.

[0014] 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 control when displaying 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.

[0015] 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, 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).

[0016] 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.

[0017] 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.

[0018] 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 representing the RGB color space.

[0019] 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.

[0020] 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 other light sources with adjustable brightness instead of the plurality of LED light sources arranged in a matrix.

[0021] For example, the image display system 1 may be mounted on 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.

[0022] The image display system 1 to be mounted on a vehicle is designed to satisfy 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.

[0023] For example, the display controller 40 performs local dimming processing to independently adjust the brightness of the multiple LED backlights according to the brightness (e.g., pixel values) of the image displayed on the display 50. During the local dimming processing, the display controller 40 performs compensation control to prevent the brightness of the surrounding image from increasing due to light leaking around the position opposite the lit LED backlight. 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.

[0024] 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.

[0025] The display engine 200 includes an image input unit 210, a memory 220, a warping unit 230, an input color statistics acquisition unit 240, a local dimming unit 250, an output brightness 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.

[0026] The image input unit 210 receives image data (e.g., 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 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 input image data VIN after the distortion correction to the local dimming unit 250.

[0027] The input color statistics acquisition unit 240 sequentially acquires an average input video luminance AIVB, which is the average of pixel values ​​for one screen (one frame) included in the input image data VIN input from the warping unit 230 to the local dimming unit 250. For example, the input color statistics acquisition unit 240 acquires the average input video luminance AIVB by calculation. The average input video luminance AIVB is an example of first statistical data. The input image data VIN is an example of first image information, and the input color statistics acquisition unit 240 is an example of a first statistics acquisition unit.

[0028] Input color statistics acquisition unit 240 outputs the acquired average input video luminance AIVB to processor 400 via register interface 280 and bus 500. Note that input color statistics acquisition unit 240 may have a storage unit such as a buffer that holds average input video luminance AIVB. In this case, the average input video luminance AIVB held in the storage unit may be read out by processor 400.

[0029] The display controller 40 has a local dimming function. That is, a brightness control unit 251 of the local dimming unit 250 generates a backlight control signal BLCNT that adjusts the brightness of the backlight 60 in FIG. 1 based on the input image data VIN, and outputs the generated backlight control signal BLCNT to the backlight 60.

[0030] Furthermore, the luminance control unit 251 outputs luminance information LINF indicating the luminance of each of the plurality of LED light sources of the backlight 60 to the output luminance statistics acquisition unit 260. For example, the luminance information LINF may include the same information as the information included in the backlight control signal BLCNT indicating the luminance of each of the plurality of LED light sources, or may be the backlight control signal BLCNT itself. A method for adjusting the luminance of the backlight 60 by the luminance control unit 251 is described in FIG. 4. The luminance information LINF and the backlight control signal BLCNT are examples of backlight control information.

[0031] The pixel compensation unit 252 of the local dimming unit 250 corrects pixel values ​​(e.g., luminance values) of the input image data VIN based on the luminance of the backlight 60 adjusted by the luminance control unit 251, and outputs the corrected pixel values ​​as output image data VOUT to the image output unit 270. The output image data VOUT is an example of second image information. For example, the pixel compensation unit 252 performs correction such that pixel values ​​in areas where the luminance of the backlight 60 is high are relatively small, and pixel values ​​in areas where the luminance of the backlight 60 is low are relatively large. At this time, the pixel compensation unit 252 performs correction of the pixel values ​​taking into account light leakage to the periphery of each LED light source. The method of image correction by the local dimming unit 250 is described with reference to FIGS. 5 and 6.

[0032] The output brightness statistics acquisition unit 260 sequentially acquires the brightness information LINF output from the local dimming unit 250 for each screen (each frame). The output brightness statistics acquisition unit 260 acquires the average backlight brightness ABB, which is the average brightness of each LED light source included in the brightness information LINF. For example, the output brightness statistics acquisition unit 260 acquires the average backlight brightness ABB by calculation. The average backlight brightness ABB is an example of second statistical data. The output color statistics acquisition unit 290 is an example of a second statistics acquisition unit.

[0033] The output brightness statistics acquisition unit 260 outputs the acquired average backlight brightness ABB to the processor 400 via the register interface 280 and the bus 500. The output brightness statistics acquisition unit 260 may have a storage unit such as a buffer that stores the average backlight brightness ABB. In this case, the average backlight brightness stored in the storage unit may be read out by the processor 400.

[0034] The image output unit 270 transmits the output 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. 1, causing the display 50 to display an image.

[0035] The memory 300 stores, for example, an image display control program executed by the processor 400, data used in 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.

[0036] Furthermore, the processor 400, for example, executes an image display control program to detect an abnormality in the brightness control unit 251 based on the average input video luminance AIVB acquired by the input color statistics acquisition unit 240 and the average backlight luminance ABB acquired by the output luminance statistics acquisition unit 260. In the processor 400, the functional unit that detects an abnormality in the luminance control unit 251 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 threshold information received from outside the processor 400. The threshold information may be supplied from outside the image display system 1.

[0037] When processor 400 does not acquire either or both of average input video luminance AIVB from input color statistics acquisition unit 240 and average backlight luminance ABB from output luminance statistics acquisition unit 260, processor 400 suppresses the process of detecting an abnormality in luminance control unit 251. The process of detecting an abnormality in luminance control unit 251 is described with reference to FIGS. 7 to 10.

[0038] Fig. 3 is a block diagram showing an example of the local dimming unit 250 in Fig. 2. The register interface 280 and the 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.

[0039] The luminance distribution calculation unit 253 receives from the luminance control unit 251 luminance information LINF indicating the luminance of each LED light source and an LSF (Lighting Spread Function), which is a luminance distribution function when only one LED light source is lit. 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 leakage of light to the surroundings for each LED light source, and outputs information indicating 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 values ​​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 value of the luminance distribution, the closer it is to 0, and the higher the luminance value, the closer it is to 1.

[0040] 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)

[0041] Furthermore, the RGB correction unit 254 uses equations (2-1), (2-2), and (2-3) to multiply the pixel value of each color component of each pixel included in the input image data VIN by the gain calculated by equation (1) to calculate a correction value for the pixel value of each color component. The symbol R in equation (2-1) indicates the pixel value of a red pixel. The symbol G in equation (3-2) 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)

[0042] For example, the pixel value for each color component of each pixel in the input image data VIN is normalized to be greater than or equal to 0 and less than or equal to 1. Therefore, when the image input unit 210 in Fig. 2 inputs 8-bit image data (0 to 255) for each pixel, the maximum value of 255 becomes 1 in the input image data VIN. The RGB correction unit 254 outputs the calculated corrected pixel value to the saturation processing unit 255 as image data VC.

[0043] For example, each pixel value of the image data VC is expressed in 12 bits, with the minimum value being 0 and the maximum value being 4095. Note that each pixel value of the image data VC may be expressed in a number of bits other than 12 bits (for example, 10 bits or 14 bits). Furthermore, when each pixel value of the input 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 1048576).

[0044] The saturation processing unit 255 generates output image data VOUT by setting the maximum pixel value of the image data VC to 1 and normalizing the other pixel values ​​to be greater than or equal to 0 and less than 1. The saturation processing unit 255 outputs the generated output image data VOUT to the display 50.

[0045] 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 the input image data VIN corresponding to the input image. Here, the maximum value ZMAX and the average value ZAVE are calculated from the pixel values ​​of the red pixels, green pixels, and blue pixels corresponding to each LED zone, with the maximum value being "1" and the minimum value being "0."

[0046] 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 and the output brightness statistics acquisition unit 260. In equation (3), the symbol α is a parameter for adjusting the brightness, and is set, for example, between 0 and 1. For example, when the brightness adjustment parameter α is 0.5, the maximum value ZMAX and the average value ZAVE are mixed 50% each. For example, the brightness adjustment parameter α may be set by the user who uses the image display system 1, or may be set externally. Brightness of each LED zone=α×ZMAX+(1−α)×ZAVE (3)

[0047] 5 is a diagram showing an example of a luminance distribution generated by the luminance distribution calculation unit 253 of FIG. 3. Because light emitted from each LED light source spreads to adjacent LED zones, the luminance distribution is calculated taking into account the spread (bleeding) of light. The luminance distribution calculation unit 253 calculates the luminance distribution by convolving the luminance information LINF for each LED zone of the backlight 60 with the luminance distribution function LSF.

[0048] In the equation shown in Figure 5, the symbol x represents the horizontal coordinate that identifies the LED zone, and the symbol y represents the vertical coordinate that identifies the LED zone. bl(x', y') represents the luminance of each LED zone, and lsf(x-x', y-y') represents 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.

[0049] Fig. 6 is a diagram showing an example of correcting the luminance of an image by the RGB correction unit 254 in Fig. 3. When the input image data VIN is output as the output 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 will not be displayed with the correct luminance.

[0050] For this reason, the RGB correction unit 254 uses equation (1) to calculate the gain for each pixel (for each of RGB) of the input image data VIN, and multiplies the pixel value of the input image data VIN by the calculated gain to correct the pixel value, thereby offsetting the luminance of the backlight 60. This makes it possible to correctly set the luminance of an image displayed on the display 50 using light from the backlight 60, the luminance of whose LED light source is individually adjusted according to the luminance of the image.

[0051] 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 is set to 1, which is the pixel value of the output image data VOUT.

[0052] FIG. 7 is a diagram showing an example of statistical information acquired by the input color statistics acquisition unit 240 and the output luminance statistics acquisition unit 260 in FIG.

[0053] The input color statistics acquisition unit 240 calculates the maximum pixel value MAX (the maximum value among the pixel values ​​of the red pixels, the green pixels, and the blue pixels) for each pixel in the input image data VIN for each frame.The input color statistics acquisition unit 240 then calculates the average input video luminance AIVB by dividing the total of the maximum pixel values ​​MAX by the total number of pixels. Figure 7 shows an example of calculations by the input color statistics acquisition unit 240 when the number of pixels is "4" (2 pixels horizontally and 2 pixels vertically).

[0054] The output brightness statistics acquisition unit 260 acquires the brightness (set brightness) of each LED light source of the backlight 60 based on the brightness information LINF received from the brightness control unit 251. The output brightness statistics acquisition unit 260 acquires the average backlight brightness ABB by dividing the sum of the acquired brightness of each LED light source by the total number of LED light sources. Fig. 7 shows an example of calculation by the output brightness statistics acquisition unit 260 when the number of LED light sources is 10 (5 horizontally and 2 vertically).

[0055] 8 is a diagram showing an example of thresholds used to determine whether or not there is an abnormality in the brightness control unit 251 of FIG. 3. The processor 400 determines whether or not there is an abnormality in the brightness of the backlight 60 for each frame of input image data VIN. For example, the processor 400 determines an upper threshold and a lower threshold, which are the range of normal brightness of the backlight 60, based on the average input video brightness AIVB of the frame to be determined acquired by the input color statistics acquisition unit 240. The upper threshold is an example of an upper limit value, and the lower threshold is an example of a lower limit value.

[0056] For example, in a pixel region corresponding to an LED zone, which is an illumination zone of one LED light source, if at least one pixel has a pixel value of "1" (i.e., white), the maximum value ZMAX in equation (3) becomes "1." In equation (3), if the maximum value ZMAX is "1" and the brightness adjustment parameter α is greater than "0," the brightness of the LED zone calculated by equation (3) becomes higher than the average value ZAVE of the pixel values ​​of the pixel region corresponding to the LED zone, and becomes the upper limit. Therefore, by applying this condition (ZMAX = "1") to equation (3) and using the average input video brightness AIVB instead of the average value ZAVE of the pixel values ​​corresponding to the LED zone in equation (3), the upper limit threshold can be calculated by equation (4): Upper limit threshold = α + (1 - α) × AIVB ... (4)

[0057] Furthermore, the luminance of each LED zone shown in equation (3) becomes the average value ZAVE when the luminance adjustment parameter α is "0". Therefore, by applying this condition (α="0") to equation (3) and using the average input video luminance AIVB instead of the average value ZAVE of the pixel values ​​corresponding to the LED zone in equation (3), the lower threshold value can be calculated by equation (5). Lower threshold value=AIVB (5)

[0058] For example, when α=“0.5” and the average input image luminance AIVB of the target frame is “0.5”, the upper threshold is “0.75” from equation (4), and the lower threshold is “0.5” from equation (5).

[0059] Then, if the average backlight luminance ABB is not included in the range between the upper and lower thresholds for the average input video luminance AIVB of the frame to be determined, the processor 400 determines that there is an abnormality in the luminance control unit 251 (NG, black circle). For example, an abnormality in the luminance control unit 251 occurs due to an abnormality in the generation process of the luminance information LINF and the backlight control signal BLCNT. On the other hand, if the average backlight luminance ABB at the average input video luminance AIVB of the frame to be determined is included in the range between the upper and lower thresholds, the processor 400 determines that the luminance control unit 251 is normal (OK, white circle).

[0060] Fig. 9 is a flow chart showing an example of processing for determining an abnormality in the brightness control unit 251 by the processor 400 of Fig. 3. That is, Fig. 9 shows an example of an image display control method by the processor 400 and an image display control program executed by the processor 400. The flow shown in Fig. 9 is started, for example, when the image display system 1 or the display controller 40 is started. Note that the processing from step S10 to step S70 is performed for each frame.

[0061] First, in step S10, the processor 400 causes the image input unit 210 to acquire frame image data. Next, in step S20, the processor 400 causes the input color statistics acquisition unit 240 to acquire the average input video luminance AIVB of the input image data VIN.

[0062] Next, in step S30, the processor 400 calculates upper and lower thresholds for the average backlight luminance ABB based on the average input image luminance AIVB acquired in step S20. Also, after step S10, in step S40, the processor 400 causes the output luminance statistics acquisition unit 260 to acquire the average backlight luminance ABB.

[0063] After steps S30 and S40, in step S60, the processor 400 determines whether the average backlight luminance ABB obtained in step S40 is within the range between the upper and lower thresholds determined in step S30. If the average backlight luminance ABB is within the range between the upper and lower thresholds, the processor 400 determines that the luminance control unit 251 is normal, and returns the process to step S10. If the average backlight luminance ABB is not within the range between the upper and lower thresholds, the processor 400 determines that the luminance control unit 251 is abnormal, and proceeds to step S70.

[0064] In step S70, processor 400 determines whether or not the content of the image to be displayed on display 50 has been switched. If the content has been switched, processor 400 determines that the content switch has caused an increase in the amount of deviation of one or both of average input video luminance AIVB and average backlight luminance ABB, and that an abnormality has been detected in luminance control unit 251.

[0065] Then, the processor 400 returns the process to step S10. That is, when the image content is switched, the processor 400 also suppresses the process of detecting an abnormality in the brightness control unit 251 when the average backlight luminance ABB is not within the range between the upper threshold and the lower threshold. When the content is not switched, the processor 400 determines that an abnormality has occurred in the brightness control unit 251, and proceeds to step S80.

[0066] In step S80, the processor 400 performs processing for when an abnormality in the brightness control unit 251 is detected, and ends the processing shown in Fig. 9. An example of step S80 is shown in Fig. 10.

[0067] In addition, if the processor 400 determines that content has been switched in step S70, it may not determine whether there is an abnormality in step S60 for at least one frame period, and may return the processing to step S10, assuming that the brightness control unit 251 is normal.

[0068] Furthermore, the processor 400 may suppress the process of detecting an abnormality in the brightness control unit 251 in step S60 for at least one frame period when the image display system 1 or the display controller 40 is started up. Then, the processor 400 may return the process to step S10 without making the determination in step S60, assuming that the brightness control unit 251 is normal. This makes it possible to prevent an abnormality in the brightness control unit 251 from being mistakenly detected due to image disturbances when switching content or starting up the device.

[0069] 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 bypasses the pixel compensation unit 252 and outputs the input image data VIN to the display 50 as the output image data VOUT. This prevents the RGB correction unit 254 from generating image data VC using an incorrect luminance distribution when the luminance information LINF is abnormal due to an abnormality in the luminance control unit 251 and the luminance distribution calculation unit 253 cannot generate a normal luminance distribution.

[0070] Next, in step S82, the processor 400 stops the dimming by the local dimming unit 250, turns on all the LED light sources of the backlight 60, and sets the backlight 60 to a preset brightness (for example, the highest 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. This allows an image to be displayed on the display 50 without reducing the brightness when the abnormality in the brightness control unit 251 is a reduction in brightness.

[0071] Next, in step S83, the processor 400 determines whether or not display of an icon indicating an abnormality is permitted for the brightness control unit 251. If display of an icon indicating an abnormality is permitted, the processor 400 proceeds to step S84. If display of an icon indicating an abnormality is not permitted, the processor 400 ends the process shown in FIG. 10 .

[0072] In step S84, the processor 400 causes the display 50 to display an icon indicating an abnormality, and ends the processing shown in Fig. 10. In step S84, the processor 400 may directly control the display 50 and cause the display 50 to display the icon indicating an abnormality using an OSD (On Screen Display) function of the display 50. Alternatively, the processor 400 may cause the display 50 to display the icon indicating an abnormality 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.

[0073] As described above, in this embodiment, it is possible to detect abnormalities in the brightness control unit 251, which could not be detected in the past, based on the input image data VIN input to the pixel compensation unit 252 and the brightness information LINF output from the brightness control unit 251.

[0074] The processor 400 calculates upper and lower thresholds of the average backlight luminance ABB for determining whether an abnormality has occurred in the luminance control unit 251, based on the average input video luminance AIVB of the input image data VIN input to the local dimming unit 250. This makes it possible to appropriately set the upper and lower thresholds for detecting an abnormality in the luminance control unit 251 in accordance with the characteristics of the image represented by the input image data VIN for each frame. As a result, it is possible to improve the accuracy of determining whether an abnormality has occurred in the luminance control unit 251.

[0075] When switching between contents or starting up the display controller 40, the processor 400 does not detect an abnormality in the brightness control unit 251 for at least one frame period. This makes it possible to prevent an abnormality in the brightness control unit 251 from being mistakenly detected due to image disturbances or the like when switching between contents or starting up.

[0076] When the processor 400 detects an abnormality in the luminance control unit 251, it stops the pixel value correction operation by the pixel compensation unit 252. This prevents the RGB correction unit 254 from generating image data VC using an incorrect luminance distribution when the luminance information LINF is abnormal due to an abnormality in the luminance control unit 251 and the luminance distribution calculation unit 253 cannot generate a normal luminance distribution.

[0077] When an abnormality in the brightness control unit 251 is detected, all of the LED light sources of the backlight 60 are turned on, so that if the abnormality in the brightness control unit 251 is a decrease in brightness, an image can be displayed on the display 50 without decreasing the brightness. Furthermore, when an abnormality in the brightness control unit 251 is detected, an icon indicating the abnormality can be displayed on the display 50 to notify the user or the like of the abnormality in the brightness control unit 251. In practice, the icon indicating the abnormality is one or both of a figure and a character that allows the user or the like to recognize the abnormality in the display controller 40.

[0078] Furthermore, even if a malfunction in the brightness control unit 251 prevents normal local dimming processing and causes the contrast of the image displayed on the display device 70 to be low, the malfunction in the brightness control unit 251 can be detected and all of the LED light sources of the backlight 60 can be turned on. This makes it possible to increase the contrast of the image displayed on the display device 70 and satisfy the ASIL requirements.

[0079] Second Embodiment Fig. 11 is a block diagram showing an example of a display controller according to a second embodiment. Elements similar to those in Fig. 2 are given the same reference numerals, and detailed descriptions thereof will be omitted. A display controller 40A shown in Fig. 11 is installed in place of the display controller 40 in the image display system 1 of Fig. 1, for example.

[0080] The display controller 40A has a display engine 200A instead of the display engine 200 in Fig. 2. The display engine 200A has the same configuration as the display engine 200 in Fig. 2, except that an output color statistics acquisition unit 290 is added to the display engine 200 in Fig. 2.

[0081] Output color statistics acquisition unit 290 sequentially acquires average output video luminance AOVB, which is the average of pixel values ​​for one screen (one frame) included in output image data VOUT output from local dimming unit 250 to image output unit 270. For example, output color statistics acquisition unit 290 acquires average output video luminance AOVB by calculation.

[0082] In this embodiment, the average input video luminance AIVB is an example of first statistical data. The input color statistics acquisition unit 240 is an example of a first statistical acquisition unit. The average output video luminance AOVB is an example of second statistical data. The output color statistics acquisition unit 290 is an example of a second statistical acquisition unit. The average backlight luminance ABB is an example of third statistical data. The output luminance statistics acquisition unit 260 is an example of a third statistical acquisition unit.

[0083] Output color statistics acquisition unit 290 outputs the acquired average output video luminance AOVB to processor 400 via register interface 280 and bus 500. Note that output color statistics acquisition unit 290 may have a storage unit such as a buffer that holds average output video luminance AOVB. In this case, the average output video luminance AOVB held in the storage unit may be read out by processor 400.

[0084] Fig. 12 is a block diagram showing an example of the input color statistics acquisition unit 240, output luminance statistics acquisition unit 260, and output color statistics acquisition unit 290 connected to the local dimming unit 250 in Fig. 11. The register interface 280 and bus 500 in Fig. 2 are omitted from Fig. 12. Except for the addition of the output color statistics acquisition unit 290, the configurations of the local dimming unit 250, input color statistics acquisition unit 240, and output luminance statistics acquisition unit 260 and the connection relationships of the respective elements are the same as those in Fig. 3.

[0085] Input color statistics acquisition unit 240 acquires average input video luminance AIVB, which is statistical data of input image data VIN normalized to a range from 0 to 1. Output color statistics acquisition unit 290 acquires average output video luminance AOVB, which is statistical data of output image data VOUT normalized to a range from 0 to 1. This allows processor 400 to calculate upper and lower thresholds (described below) without matching the scales (number of bits, etc.) of average input video luminance AIVB and average output video luminance AOVB to each other.

[0086] Fig. 13 is a diagram showing an example of statistical data acquired by the input color statistics acquisition unit 240, the output luminance statistics acquisition unit 260, and the output color statistics acquisition unit 290 in Fig. 12. The statistical data (average input video luminance AIVB and average backlight luminance ABB) acquired by the input color statistics acquisition unit 240 and the output luminance statistics acquisition unit 260 are the same as those in Fig. 7.

[0087] The output color statistics acquisition unit 290 calculates the maximum pixel value MAX (the maximum value among the pixel values ​​of the red pixels, the green pixels, and the blue pixels) for each pixel in the output image data VOUT of each frame. Then, the output color statistics acquisition unit 290 calculates the average output video luminance AOVB by dividing the sum of the maximum pixel values ​​MAX of all pixels by the total number of pixels.

[0088] Fig. 14 is a diagram showing an example of threshold values ​​used to determine whether there is an abnormality in the brightness control unit 251 of Fig. 12. The processor 400 determines whether there is an abnormality in the brightness of the backlight 60 for each frame of input image data VIN.

[0089] As explained in Fig. 6, in the correction of the brightness of an image by the RGB correction unit 254, the input image data VIN is divided by the brightness (brightness distribution) of the backlight 60, thereby canceling out the brightness of the backlight 60 as shown in equation (6). By moving the "backlight brightness" on the left side of equation (6) to the right side, equation (7) is obtained. Input image data VIN / backlight brightness = output image data VOUT (6) Input image data VIN = backlight brightness × output image data VOUT (7)

[0090] For example, in equation (7), "input image data VIN" can be approximated to "average input video luminance AIVB" acquired by input color statistics acquisition unit 240. "output image data VOUT" can be approximated to "average output video luminance AOVB" acquired by output color statistics acquisition unit 290. "Backlight luminance" can be approximated to "average backlight luminance ABB" acquired by output luminance statistics acquisition unit 260. Then, by replacing equation (7) with the respective approximate terms, equation (8) is obtained. That is, "average backlight luminance ABB × average output video luminance AOVB" has a value equivalent to (approximate to) "average input video luminance AIVB". Average input video luminance AIVB ≈ average backlight luminance ABB × average output video luminance AOVB ... (8)

[0091] In this embodiment, processor 400 determines that there is an abnormality in brightness control unit 251 if "average backlight brightness ABB × average output video brightness AOVB" in "average input video brightness AIVB" acquired by input color statistics acquisition unit 240 does not fall within a predetermined range. The predetermined range is indicated by an upper threshold and a lower threshold. "average backlight brightness ABB × average output video brightness AOVB" is an example of output statistical data. The upper threshold is an example of an upper limit value, and the lower threshold is an example of a lower limit value.

[0092] Here, the luminance distribution of the backlight 60 is calculated taking into account the bleeding of light into adjacent LED zones, as explained in FIG. 5 . The actual luminance of each LED zone of the backlight 60 is higher than the set luminance set for each LED light source, due to the bleeding from adjacent LED zones being added. In other words, the "average backlight luminance ABB" is lower than the average value of the actual luminance of the LED zones of the backlight 60, because the bleeding from adjacent LED zones is not taken into account.

[0093] Therefore, "average backlight luminance ABB x average output video luminance AOVB" in equation (8) will not exceed the product of the actual luminance of backlight 60 and the output image data VOUT output from pixel compensation unit 252, and the upper threshold of "average backlight luminance ABB x average output video luminance AOVB" in equation (8) will not exceed average input video luminance AIVB. Therefore, "average input video luminance AIVB" itself is set as the upper threshold (equation (9)). Upper limit threshold = average input video luminance AIVB (9)

[0094] The lower threshold of "average backlight luminance ABB x average output video luminance AOVB" must be set taking into account bleeding from adjacent LED zones, since "average backlight luminance ABB" is smaller than the average value of the actual luminance of the LED zones of backlight 60. Therefore, the lower threshold is set to a value obtained by multiplying "average input video luminance AIVB" by a luminance adjustment parameter β (0 < β < 1) (Equation (10)). The luminance adjustment parameter β is an example of a coefficient by which the average input video luminance AIVB is multiplied. For example, the luminance adjustment parameter β is set to the ratio A / B of area A and area B shown in FIG. 14. Area A is the integral value of the luminance when one LED light source is turned on, without taking light bleeding into account. Area B is the integral value of the luminance of the luminance distribution shown in FIG. 5, taking light bleeding into account. Lower threshold = average input video luminance AIVB x β (10)

[0095] "Average input video luminance AIVB" in equation (9) and "average input video luminance AIVB × β" in equation (10) are examples of input statistical data. Then, when "average backlight luminance ABB × average output video luminance AOVB" of the frame to be determined is not included in the range between the upper and lower thresholds shown in equations (9) and (10), processor 400 determines that there is an abnormality in luminance control unit 251 (NG, black circle). When "average backlight luminance ABB × average output video luminance AOVB" of the frame to be determined is included in the range between the upper and lower thresholds shown in equations (9) and (10), processor 400 determines that there is an abnormality in luminance control unit 251 (OK, white circle).

[0096] Fig. 15 is a flow chart showing an example of processing for determining an abnormality in the brightness control unit 251 by the processor 400 of Fig. 12. That is, Fig. 15 shows an example of an image display control method by the processor 400 and an image display control program executed by the processor 400. Detailed description of processing similar to that of Fig. 9 will be omitted. The flow shown in Fig. 15 starts, for example, when the image display system 1 or the display controller 40 is started. Note that the processing from step S10 to step S70 is performed for each frame.

[0097] In the flow shown in Fig. 15, steps S30A and S60A are performed instead of steps S30 and S60 in Fig. 9. In addition, step S50 is added between steps S30A and S60A. The other processes in Fig. 15 are the same as those in Fig. 9. The process in step S80 is the same as that shown in Fig. 10.

[0098] In step S30A, processor 400 calculates an upper threshold and a lower threshold corresponding to the product of average backlight luminance ABB and average output image luminance AOVB based on average input image luminance AIVB calculated in step S20 and a predetermined luminance adjustment parameter β. Next, in step S50, processor 400 causes output color statistics acquisition unit 290 to acquire average output image luminance AOVB of output image data VOUT. Note that step S50 may be performed in parallel with steps S20 and S40.

[0099] After steps S40 and S50, in step S60A, processor 400 calculates the product "ABB x AOVB" of the average backlight luminance ABB and the average output video luminance AOVB obtained in steps S40 and S50. Then, processor 400 determines whether the calculated product "ABB x AOVB" is within the range between the upper and lower thresholds calculated in step S30A.

[0100] If the product "ABB x AOVB" is within the range between the upper and lower thresholds, the processor 400 determines that the brightness control unit 251 is normal, and returns the process to step S10. If the product "ABB x AOVB" is not within the range between the upper and lower thresholds, the processor 400 determines that the brightness control unit 251 is abnormal, and moves the process to step S70. The processes of steps S70 and S80 are the same as the processes of steps S70 and S80 in FIG. 9.

[0101] As described above, this embodiment can also achieve the same effects as the above-described embodiments. For example, it is possible to detect an abnormality in the brightness control unit 251, which could not be detected in the past, based on the input image data VIN input to the pixel compensation unit 252, the output image data VOUT output from the pixel compensation unit 252, and the brightness information LINF output from the brightness control unit 251.

[0102] Furthermore, in this embodiment, the processor 400 can determine the upper and lower thresholds without using the brightness adjustment parameter α. This makes it possible to prevent the upper and lower thresholds from fluctuating depending on the brightness adjustment parameter α set by a user, etc. As a result, for example, it is possible to prevent the normal range of brightness of the backlight 60, which is set by the upper and lower thresholds, from widening depending on the brightness adjustment parameter α, and to prevent a decrease in the accuracy of abnormality detection by the brightness control unit 251.

[0103] In the first and second embodiments described above, the upper and lower thresholds are calculated in step S30 of FIG. 9 or step S30A of FIG. 15 based on pixel values ​​of the input image data VIN input to the local dimming unit 250. However, when an image to be displayed on the display device 70 is predetermined, the upper and lower thresholds may be calculated from pixel values ​​acquired in advance corresponding to the image to be displayed. In this case, the upper and lower thresholds corresponding to the image to be displayed are stored in the memory 300 and referenced by the processor 400. In this case, the process of calculating the upper and lower thresholds in step S30 of FIG. 9 and step S30A of FIG. 15 is omitted.

[0104] In the first and second embodiments described above, the upper and lower thresholds are calculated based on all pixel values ​​of the input image data VIN input to the local dimming unit 250, and an abnormality in the brightness control unit 251 is detected based on the calculated upper and lower thresholds. However, instead of all pixel values ​​included in the input image data VIN, the upper and lower thresholds may be calculated based on pixel values ​​of a smaller number of pixels obtained by thinning out some of the pixels included in the input image data VIN. In this case, the calculation load of the input color statistics acquisition unit 240 and the output color statistics acquisition unit 290 can be reduced, and the calculation load of the upper and lower thresholds by the processor 400 can be reduced. As a result, an increase in power consumption of the display controllers 40 and 40A can be suppressed.

[0105] 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.

[0106] 1 Image display system 10 Head unit 20 Serializer 30 Deserializer 40, 40A Display controller 50 Display 60 Backlight 200, 200A Display engine 210 Image input unit 220 Memory 230 Warping unit 240 Input color statistics acquisition unit 250 Local dimming unit 251 Luminance control unit 252 Pixel compensation unit 253 Luminance distribution calculation unit 254 RGB correction unit 255 Saturation processing unit 260 Output luminance statistics acquisition unit 270 Image output unit 280 Register interface 290 Output color statistics acquisition unit 300 Memory 400 Processor 500 Bus ABB Average backlight luminance AIVB Average input video luminance AOVB Average output video luminance BLCNT Backlight control signal LINF Luminance information LSF Luminance distribution function VC Image data VIN Input image data VOUT Output image data

Claims

1. An image display control device having a local dimming function, a luminance control unit that generates backlight control information used to control a plurality of light sources included in the backlight, based on first image information representing an input image; 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 representing an output image; 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 the luminance values ​​of each light source included in the backlight control information; an abnormality detection unit that detects an abnormality in the brightness control unit depending on whether the second statistical data is included in a range between an upper limit value and a lower limit value determined by the first statistical data; An image display control device having the above configuration.

2. the first statistical data is an average luminance value of the input image calculated based on pixel values ​​of the first image information; The second statistical data is an average value of the luminance values ​​of the light sources included in the backlight control information. The image display control device according to claim 1 .

3. An image display control device having a local dimming function, a luminance control unit that generates backlight control information used to control a plurality of light sources included in the backlight, based on first image information representing an input image; 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 representing an output image; 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; a third statistics acquisition unit that acquires third statistical data of the luminance values ​​of the light sources included in the backlight control information; an abnormality detection unit that detects an abnormality in the brightness control unit depending on whether output statistical data obtained based on the second statistical data and the third statistical data is included in a range between an upper limit value and a lower limit value determined by input statistical data obtained based on the first statistical data; An image display control device having the above configuration.

4. the first statistical data is an average luminance value of the input image calculated based on pixel values ​​of the first image information; the input statistical data is the first statistical data or a value obtained by multiplying the first statistical data by a coefficient, the second statistical data is an average luminance value of the output image calculated based on pixel values ​​of the second image information, the third statistical data is an average value of the luminance values ​​of the light sources included in the backlight control information, The output statistical data has a value corresponding to an average luminance value of the input image, the value being obtained by multiplying the second statistical data and the third statistical data. The image display control device according to claim 3.

5. The abnormality detection unit suppresses a detection process of an abnormality in the luminance control unit for at least one frame period when a content of an image to be displayed on a display unit is switched, the content being indicated by the second image information, or when the image display control device is started. The image display control device according to claim 1 .

6. The abnormality detection unit outputs the first image information as the second image information regardless of an operation of the pixel compensation unit when an abnormality in the brightness control unit is detected, and turns on the plurality of light sources regardless of an operation of the brightness control unit. The image display control device according to claim 1 .

7. The abnormality detection unit suppresses a detection process of an abnormality in the luminance control unit for at least one frame period when a content of an image to be displayed on a display unit is switched, the content being indicated by the second image information, or when the image display control device is started. The image display control device according to claim 3.

8. The abnormality detection unit outputs the first image information as the second image information regardless of an operation of the pixel compensation unit when an abnormality in the brightness control unit is detected, and turns on the plurality of light sources regardless of an operation of the brightness control unit. The image display control device according to claim 3.

9. An image display control device having a display engine that performs local dimming processing and a processor that controls an 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; generating backlight control information used to control a plurality of light sources included in a 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 representing an output image; obtaining first statistical data of pixel values ​​included in the first image information; Obtaining second statistical data of the luminance values ​​of each light source included in the backlight control information; outputting the second image information to the display unit; The processor detects an abnormality in the generation process of the backlight control information depending on whether the second statistical data is included in a range between an upper limit value and a lower limit value determined by the first statistical data. Image display control device.

10. An image display control device having a display engine that performs local dimming processing and a processor that controls an 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; generating backlight control information used to control a plurality of light sources included in a 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 representing an output image; 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; Obtaining third statistical data of the luminance values ​​of the light sources included in the backlight control information; outputting the second image information to the display unit; The processor detects an abnormality in the generation process of the backlight control information depending on whether output statistical data obtained based on the second statistical data and the third statistical data is included in a range between an upper limit value and a lower limit value determined by input statistical data obtained based on the first statistical data. Image display control device.

11. An image display control device having a local dimming function, a luminance control unit that generates backlight control information used to control a plurality of light sources included in the backlight, based on first image information representing an input image; 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 representing an output image; a first statistics acquisition unit that acquires first statistical data of the luminance values ​​of each light source included in the backlight control information; an abnormality detection unit that detects an abnormality in the brightness control unit according to whether the first statistical data is included in a range between an upper limit value and a lower limit value determined by an image to be displayed; An image display control device having the above configuration.

12. An image display control device having a local dimming function, a luminance control unit that generates backlight control information used to control a plurality of light sources included in the backlight, based on first image information representing an input image; 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 representing an output image; a first statistics acquisition unit that acquires first statistical data of pixel values ​​included in the second image information; a second statistics acquisition unit that acquires second statistical data of the luminance values ​​of each light source included in the backlight control information; an abnormality detection unit that detects an abnormality in the brightness control unit according to whether output statistical data obtained based on the first statistical data and the second statistical data is within a range between an upper limit value and a lower limit value determined by an image to be displayed; An image display control device having the above configuration.

13. The image display control device according to claim 1 ; A display unit; The backlight is disposed opposite to the display unit; and a head unit that generates an image and outputs the first image information indicating the generated image to the image display control device; An image display system comprising:

14. The image display control device according to claim 3 ; A display unit; The backlight is disposed opposite to the display unit; and a head unit that generates an image and outputs the first image information indicating the generated image to the image display control device; An image display system comprising:

15. An image display control method using an image display control device having a local dimming function, comprising: generating backlight control information used to control a plurality of light sources included in a backlight based on first image information indicating an input image by a luminance control unit included in the image display control device; 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 representing an output image; a first statistical acquisition unit of the image display control device acquires first statistical data of pixel values ​​included in the first image information; a second statistics acquisition unit of the image display control device acquires second statistical data of the luminance values ​​of the light sources included in the backlight control information; An abnormality in the brightness control unit is detected by an abnormality detection unit included in the image display control device depending on whether the second statistical data is included in a range between an upper limit value and a lower limit value determined by the first statistical data. Image display control method.

16. An image display control method using an image display control device having a local dimming function, comprising: generating backlight control information used to control a plurality of light sources included in a backlight based on first image information indicating an input image by a luminance control unit included in the image display control device; 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 representing an output image; a first statistical acquisition unit of the image display control device acquires first statistical data of pixel values ​​included in the first image information; A second statistical acquisition unit of the image display control device acquires second statistical data of pixel values ​​included in the second image information. a third statistical acquisition unit of the image display control device acquires third statistical data of the luminance values ​​of the light sources included in the backlight control information; An abnormality detection unit of the image display control device detects an abnormality in the brightness control unit depending on whether output statistical data obtained based on the second statistical data and the third statistical data is included in a range between an upper limit value and a lower limit value determined by input statistical data obtained based on the first statistical data. Image display control method.