JP2013218165A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that suppresses stimulation to a human eye without lowering a contrast ratio.SOLUTION: An LED backlight control map determines whether to correct a luminance control value or not for each region based on the pixel value of a pixel corresponding to an image displayed in regions into which a display screen is divided and the determined luminance control value corresponding to the region. When the determination part determines that the determined luminance control value is corrected for at least one region of the regions, the LED backlight control map corrects the luminance control value and makes the emission luminance control part control the luminance of the plurality of light emitting parts based on a corrected luminance control value.

Description

  The present invention relates to a display device having a local dimming function.

  In a liquid crystal display device, liquid crystal is sealed between two transparent substrates, and when a voltage is applied, the orientation of liquid crystal molecules is changed and the light transmittance is changed, whereby a predetermined image or the like is optically displayed. Is displayed. In this liquid crystal display device, since the liquid crystal itself is not a light emitter, for example, the back side of a transmissive liquid crystal panel is irradiated with light using a cathode tube (CFL), a light emitting diode (LED) or the like as a light source. A backlight unit is provided.

  Examples of the backlight unit include a direct type that emits light by arranging light sources such as cathode tubes and LEDs on the bottom surface.

  In a display device including a liquid crystal panel and a direct backlight unit, improvement in display quality such as visibility is required. A contrast ratio is a characteristic that affects display quality. The contrast ratio is a brightness difference between a bright part and a dark part on the display screen. If the brightness difference is large, the color and outline of the displayed image are clear and the display quality is improved.

  Since the liquid crystal display device displays an image by changing the light transmittance as described above, the contrast ratio is naturally determined by the light transmittance of the liquid crystal panel. Therefore, in the direct type backlight, the irradiation area is divided into a plurality of areas, the brightness of the light source is controlled for each area, the bright part increases the brightness of the light source, and the dark part increases the brightness of the light source. By making it lower and darker, a local dimming function that further improves the contrast ratio by combining the light transmittance control of the liquid crystal panel and the brightness control of the backlight is put into practical use.

  In local dimming, in order to make the bright part brighter and the dark part darker, the area to be brightened and the area to be darkened are specified based on the pixel value of the image data to be displayed, and the specified area is supported. Increase or decrease the brightness of the light source.

  In Patent Document 1, based on the maximum value for each unit pixel, the average value of each region is detected, and the maximum average value, the minimum average value, and the overall average value are calculated from the average value. A technique for generating a dimming curve based on the minimum dimming curve value and the maximum dimming curve value to control the backlight is described.

  In order to improve the display quality of the display device, not only brightness is controlled but also external stimuli caused by human visual non-linearity or optical illusion and perception by the brain as described in Patent Document 2, for example. In consideration of various problems associated with the difference in sensed amount, a technique for correcting the luminance of the LED has been developed.

JP 2007-183608 A JP 2004-273522 A

  The local dimming function can improve the contrast ratio. However, only the improvement of the contrast ratio is considered, and the image displayed on the display device is viewed in an attempt to make the brighter part of the display screen brighter. There is a risk that the image is displayed with such a brightness that the human eye is adversely affected.

  An object of the present invention is to provide a display device that suppresses stimulation given to the human eye without reducing the contrast ratio.

The present invention includes a display unit having a display screen on which an image based on image data composed of a plurality of pixels is displayed;
A light-emitting device that is provided for each region obtained by dividing the display screen and includes a plurality of light-emitting units that display images on the display screen by emitting light toward the corresponding regions;
Luminance control for determining the luminance control value of the plurality of light emitting units for each of the areas according to the image displayed on the display screen, and controlling the luminance of the plurality of light emitting units based on the determined luminance control value And
Whether or not to correct the determined brightness control value is determined for each area based on the pixel value of the pixel corresponding to the image displayed in the area and the determined brightness control value corresponding to the area. A determination unit to
When the determination unit determines that the determined luminance control value is to be corrected for at least one of the regions, the determined luminance control value is corrected, and the corrected luminance control value is transmitted to the light emission luminance control unit. And a correction unit that controls the luminance of the plurality of light-emitting units based on the display device.

  According to the present invention, the determination unit indicates the brightness of the screen in the region based on the pixel value of the pixel corresponding to the image displayed in the region and the determined brightness control value corresponding to the region. The brightness is calculated, the calculated brightness is compared with a predetermined threshold, and if the calculated brightness is larger than the threshold, it is determined that the determined brightness control value is corrected.

  In the present invention, when it is determined that the correction unit corrects the determined brightness control value, the correction unit corrects the determined brightness control value using the same correction coefficient for all regions. Features.

  According to the present invention, the determination unit corrects the luminance control value based on the pixel value of the pixel corresponding to the image displayed in the divided area of the display screen and the determined luminance control value corresponding to the area. And determining whether to correct the determined brightness control value for at least one of the areas by the determining unit. The correcting unit corrects the brightness control value. The light emission luminance control unit controls the luminance of the plurality of light emission units based on the corrected luminance control value.

  Since the determination is made based on the pixel value and the luminance control value, and the luminance control value is corrected as necessary, it is possible to suppress the stimulus given to the human eye without reducing the contrast ratio.

Further, according to the invention, the determination unit determines the brightness of the screen in the area based on the pixel value of the pixel corresponding to the image displayed in the area and the determined brightness control value corresponding to the area. And the calculated stimulation value is compared with a predetermined threshold value. If the calculated stimulation value is larger than the threshold value, it is determined that the determined luminance control value is corrected.
Thereby, it is possible to suppress the stimulus given to the human eye by the brightness of the display screen.

  According to the present invention, the correction unit corrects the brightness control value for all the areas using the same correction coefficient, so that only one area is corrected and the brightness with respect to the other areas is corrected. Preventing the difference in height.

It is a block diagram which shows the structure of the display apparatus 1 which is embodiment of this invention. It is a flowchart which shows a LED backlight control process. It is a flowchart which shows a stimulus value map creation process. It is a figure which shows the example of each map. It is a flowchart which shows a stimulus value determination process. It is a flowchart which shows a LED backlight control map correction process. It is a figure which shows the LED backlight control map 40 before correction | amendment, and the LED backlight control map 40a after correction | amendment. It is a figure which shows the stimulus value map 42 before correction | amendment, and the stimulus value map 42a after correction | amendment.

FIG. 1 is a block diagram showing a configuration of a display device 1 according to an embodiment of the present invention.
The display device 1 includes a video extraction unit 2, a display setting extraction unit 3, an LED backlight control map creation unit 4, a stimulus value map creation unit 5, an LED backlight control map correction unit 6, a visual protection condition database (DB) 7, A display control unit 8, a display panel 9, and a backlight 10 are provided. In addition, a video signal indicating image data is input from the external video transmission unit 20 to the display device 1, and a setting signal indicating settings related to display on the display is input from the display setting transmission unit 30.

  The image data input to the display device 1 may be image data (moving image data) for displaying a moving image or image data (still image data) for displaying a still image. The video transmission unit 20 may be any type and format of image data regardless of moving image data and still image data such as a personal computer, a hard disk recorder, a DVD player, a digital camera, and a smart phone. Good.

  The video extraction unit 2 receives the image data input from the video transmission unit 20 and stores the received image data as necessary. In addition, the video extraction unit 2 extracts, for example, image data for each frame from the received image data so that an image can be displayed on the display panel 9. The extracted image data for each frame is output to the LED backlight control map creation unit 4.

  The image data includes a plurality of pixels, and each pixel includes a coordinate value indicating a position in one screen, and a pixel value indicating a hue and density to be displayed.

  The display setting extraction unit 3 receives the setting data input from the display setting transmission unit 30, and updates and stores setting values related to display on the display as necessary. The stored set value is output to the stimulus value map creation unit.

  The display setting transmission unit 30 is realized by a remote controller, for example, and transmits a display setting value desired by the user to the display device 1 by any one of wired communication by cable connection and wireless communication such as infrared communication. The display setting extraction unit 3 does not need to output all of the setting values input from the display setting transmission unit 30 to the stimulus value map creation unit 5, but only the settings necessary for creating a stimulus value map, which will be described later, What is necessary is just to output to the preparation part 5.

  The LED backlight control map creation unit 4 creates a control map in which the brightness control value of each LED (Light Emitting Diode) light source provided in the backlight 10 is set for each LED light source in order to realize a so-called local dimming function. . The control map can be created by a procedure used for a conventionally known local dimming function.

  In the local dimming function, the display screen of the display is divided into a plurality of areas, and the brightness of the LED light source assigned to each of the divided areas is controlled for each area, thereby realizing a high contrast ratio. . In order to achieve a high contrast ratio, the luminance is controlled according to the image displayed on the display screen. For example, when displaying an image such as the night sky with the moon or the blue sky with the sun on the screen, the moon or sun is displayed brighter and more light is emitted from the display screen to the user. If this portion is displayed darker and less light is irradiated to the user from the display screen, the contrast ratio is increased.

  In the above example, the portion of the moon or sun that should be displayed brighter has a high pixel value corresponding to the moon or sun in the image data, and the pixel value corresponding to the surrounding sky is high. The pixel value is set to a low brightness value or the like. Therefore, the local dimming function refers to the pixel value of the pixel corresponding to the area, and considers how much the luminance of the LED light source assigned to each area is increased or decreased for each LED light source. The brightness control value is determined, and the brightness of each LED light source is controlled.

  The arrangement position of each LED light source provided in the backlight 10 is determined in advance, and the arrangement position of each area of the display screen is also predetermined according to each LED light source of the backlight 10. Therefore, the backlight control map determines a luminance control value for controlling the luminance of the LED light source based on the image data input from the video extraction unit 2 for each predetermined area.

  The control map is composed of area arrangement information indicating an m × n matrix area arrangement divided into m vertically and n horizontally and luminance control values for each area. The area arrangement information can be expressed as a coordinate value. For example, the area at the upper left corner or the lower left corner of the display screen is set as the arrangement position (1, 1), and the arrangement position of each area arranged in the horizontal direction from there is ( 2, 1), (3, 1)... (N-1, 1), (n, 1), and the arrangement positions of the respective areas arranged in the vertical direction are (1, 2,), (1, 3). ... (m-1, 1), (m, 1).

  The brightness control value may be any value as long as it serves as a guideline for controlling the brightness value of the LED light source arranged corresponding to each area, such as a voltage value and a current value applied to the LED light source. It may be a percentage value indicating relative luminance, where 100% is the case where light is emitted at the maximum luminance. In this embodiment, the percentage value at which light emission at the maximum luminance is 100% is set as the luminance control value.

  The LED backlight control map creation unit 4 refers to the input image data, determines the luminance control value for each area from the pixel value in each area, and associates the area arrangement information with the luminance control value for each area. And stored as a control map.

  The stimulus value map creation unit 5 is based on each pixel value of the input image data, the control map created by the LED backlight control map creation unit 4, and the set value input from the display setting extraction unit 3. To create a stimulus map. The stimulus value map includes the same area arrangement information as the control map for luminance control, and the stimulus value for each area.

  Here, the stimulus value is a value indicating the degree of stimulus to the human eye when the human visually recognizes the image displayed by the display device 1. The stimulus value is only a measure for the degree of stimulus, and just because an image is displayed under a condition that is larger than the stimulus value, it does not necessarily have an adverse effect on human eyes.

  The stimulus value is basically an area based on the pixel value in the image data to be displayed and the brightness control value, taking into account the screen brightness setting value as a parameter affecting the human eye from among the setting values. Calculated for each. In the present embodiment, an example in which the stimulus value is calculated based on the pixel value, the brightness control value, and the screen brightness setting value will be described.

  Compared with the resolution of the pixel in the image data and the resolution of the area in the luminance control value map, the resolution of the pixel is higher, so that one area includes a plurality of corresponding pixels. In calculating the stimulus value, since one value needs to be assigned to one area, the representative value of the pixel value is calculated to be one value in one area. The representative value may be, for example, the median value of the pixel values of a plurality of pixels corresponding to one area, or may be an average value. When displaying a full-color image, since one area includes pixels of three colors of RGB, the average value is, for example, (sum of R components of all pixels in area + sum of G components of all pixels in area + Calculated by (sum of B components of all pixels in area) / 3. As described above, a pixel value map in which one value is assigned to each area is created in advance.

  The stimulation value may be calculated by multiplying all these values for each area. For example, if the pixel value is 120, the brightness control value is 50%, and the screen brightness setting value is 10, the stimulus value indicating the screen brightness in that area = 120 × 50% × 10 = 600. Is calculated. Such calculation is performed for each area, and the area arrangement information and the stimulation value for each area are associated and stored as a stimulation value map.

  The LED backlight control map correction unit 6 corrects the control map once created by the LED backlight control map creation unit 4 as necessary. The LED backlight control map correction unit 6 determines whether to correct the created control map based on the stimulus value map created by the stimulus value map creation unit 5.

  As described above, since the stimulus value indicates the degree of stimulus to the human eye, if the stimulus value is equal to or greater than a predetermined threshold value, it is considered highly likely to have an adverse effect on the human eye. . Therefore, when there is a concern that the human eye may be adversely affected, the LED backlight control map is corrected and the stimulation value is lowered so as to be lower than the threshold value.

  A threshold for determining whether or not to correct the stimulus value map is stored in the visual protection condition database 7 as a visual protection condition.

  The LED backlight control map correction unit 6 is protected from the visual protection condition database 7 when the control map is input from the LED backlight control map creation unit 4 and the stimulus value map is input from the stimulus value map creation unit 5. Read the threshold value as a condition. Using the read threshold value, the stimulus value and the threshold value are compared for each area of the stimulus value map. If at least one of the plurality of areas has an stimulation value equal to or greater than the threshold value, the control map is corrected.

  The correction of the control map corrects the luminance control value of each area. For the correction of the brightness control value, for example, the brightness control value is set to a smaller value by using a predetermined correction coefficient.

  In the stimulus value map, if only an area where the stimulus value is greater than or equal to the threshold value among a plurality of areas is corrected, at least adverse effects on human eyes can be prevented. However, when only one area is corrected to reduce the luminance control value, the difference between the luminance control value of the area that has not been corrected and the luminance control value of the area that has not been corrected becomes small. That is, among the LED light sources whose luminance is controlled based on the corrected control map, the luminance of the LED light source whose luminance control value is corrected becomes low, and the luminance of the LED light source whose luminance control value is not corrected remains unchanged. Therefore, the difference in luminance is reduced. As a result, the contrast ratio when an image is displayed as the display device 1 becomes small.

  Therefore, when there is even one area where the stimulus value is equal to or greater than the threshold value, it is preferable to correct the brightness control value for all areas. Furthermore, it is preferable that all the correction coefficients for correcting the luminance control value of each area are the same coefficient.

  The display control unit 8 controls the voltage applied to each pixel of the display panel 9 based on the image data to control the light transmittance of each pixel in the display panel 9 to display an image. Further, the luminance control of the backlight 10 is performed based on the LED backlight control map.

FIG. 2 is a flowchart showing the LED backlight control process.
The LED backlight control process is started when image data is input from the video transmission unit 20. In step S1, the LED backlight control map creation unit 4 creates a control map based on the input image data. In step S2, the stimulus value map creation unit 5 creates a stimulus value map.

  FIG. 3 is a flowchart showing a stimulus value map creation process. In step S11, the LED backlight control map created in step S1 of the LED backlight control process is acquired. In step S12, a pixel value map is created based on the image data extracted by the video extraction unit 2. In step S13, the setting value extracted by the display setting extraction unit 3 is acquired. In step S14, a stimulus value map is created by calculating a stimulus value for each area based on each luminance control value of the LED backlight control map, each pixel value of the pixel value map, and the set value.

  FIG. 4 is a diagram illustrating an example of each map. 4A is a diagram showing an LED backlight control map 40, FIG. 4B is a diagram showing a pixel value map 41 of image data, and FIG. 4C is a stimulus value map 42. FIG.

  In the example shown in FIG. 4, each map is a 3 × 3 map having three vertically and three horizontally. In each map, when the position of the lower left corner area is (1, 1), in the LED backlight control map 40, for example, in the area of position (2, 3), the luminance control value is set to 100% at the maximum, and the position ( The luminance control values of (1, 1) and (3, 1) are 10%. In the pixel value map 41, the pixel value is maximum at 240 in the area of the position (2, 3), and the pixel value is minimum at 30 in the areas of the positions (1, 1) and (3, 1). The stimulation value is calculated using the above calculation formula. The brightness setting value used for the calculation is 10. Stimulus value = 240 × 100% × 10 = 2400 in the area of position (2,3), and stimulus value = 30 × 10% × 10 = 30 in the areas of position (1,1) and (3,1). is there.

  Returning to the flowchart of FIG. 2, in step S3, the stimulus value is determined by comparing the stimulus value map with the visual protection condition.

  FIG. 5 is a flowchart showing the stimulus value determination process. In step S21, the stimulus value map created in step S2 of the LED backlight control process is acquired. In step S222, a threshold for determining a stimulus value as a visual protection condition is acquired from the visual protection condition database 7. In step S23, threshold processing is performed on the stimulus value map acquired in step S21 using the threshold acquired in step S22, and it is determined whether or not a visual protection condition is satisfied. Specifically, for each area of the stimulus value map, the stimulus value corresponding to the area is compared with the threshold value, and if there is at least one area where the stimulus value is equal to or greater than the threshold value, the stimulus value map satisfies the visual protection condition. If there is no correction, that is, it is necessary to correct the luminance control value, the process proceeds to step S25. If the stimulus value is smaller than the threshold value in all areas, it is determined that the stimulus value map satisfies the visual protection condition, that is, it is not necessary to correct the brightness control value, and the process proceeds to step S24.

  In step S24, it is assumed that there is no problem in the stimulus value as a determination result, and in step S25, there is a problem in the stimulus value as a determination result.

  In the flowchart of FIG. 2, in step S4, it is determined whether or not there is a problem in the stimulus value map. In the stimulus value determination process shown in FIG. 5, if it is determined that there is no problem with the stimulus value, the process proceeds to step S6, and if it is determined that there is a problem with the stimulus value, the process proceeds to step S5.

  In step S5, the LED backlight control map is corrected. FIG. 6 is a flowchart showing the LED backlight control map correction process.

  In step S31, an attenuation rate is calculated to correct the brightness control value of the control map. For the attenuation rate, a coefficient is calculated for the stimulation value that exceeds the threshold so that the stimulation value is equal to or less than the threshold. Considering the influence on the human eye, the stimulus value should be as small as possible. However, reducing the stimulus value will reduce the brightness of the display screen, and therefore the display quality will be degraded. The attenuation rate may be determined so that the stimulus value is the same as the threshold value so that the deterioration of display quality is minimized and the human eye is not adversely affected.

  When the stimulation value exceeding the threshold is S and the threshold is T (<S), the attenuation rate R can be calculated by R = (S−T) / S. The stimulation value map 42 shown in FIG. 4C will be described as an example. If the threshold value T is 1920, for example, 2400 is detected as the stimulation value S exceeding the threshold value among the stimulation values in each area by comparing the threshold value with the stimulation value map 42. At this time, the attenuation rate R is calculated as R = (2400−1920) /2400=0.2.

  In the example shown in FIG. 4, the stimulation value S exceeding the threshold value T is only one of the stimulation values in each area of the stimulation value map 42, so the attenuation rate R is calculated based on the one stimulation value S. What is necessary is just to calculate. However, there may be a case where two or more stimulus values exceed the threshold T in the stimulus value map. In such a case, considering the influence on the human eye, it is natural that the largest stimulus value needs to be lowered to a threshold value or less, so the attenuation rate R is the maximum value among the two or more stimulus values S. Smax is selected, and R = (Smax−T) / Smax is calculated.

  In step S32, the LED backlight control map 40 is corrected using the attenuation rate R calculated in step S31.

  The LED backlight control map 40 shown in FIG. 4A will be described as an example. Based on the attenuation rate R calculated in step S31, a correction coefficient C for multiplying the luminance control value set in the LED backlight control map 40 is calculated by C = 1−R. In the LED backlight control map 40, a corrected LED backlight control map is created by uniformly multiplying all luminance control values (percentage) set in each area by the same correction coefficient C. When the luminance control value before correction is L0 (%), the luminance control value L1 (%) after correction is calculated as L1 = L0 × C.

  FIG. 7 is a diagram showing the LED backlight control map 40 before correction and the LED backlight control map 40a after correction. FIG. 7A shows the LED backlight control map 40 before correction, and FIG. 7B shows the LED backlight control map 40a after correction. In the above example, since the attenuation rate R is 0.2, the correction coefficient is calculated as C = 1−0.2 = 0.8. Using this correction coefficient C, the luminance control value of each area of the LED backlight control map 40 is corrected. The luminance control value of the area at position (2, 3), which was the maximum luminance control value before correction, is 100 (%) × 0.8 by multiplying 100 (%) by the correction coefficient C = 0.8. = 80 (%) is corrected. The luminance control value is corrected using the same correction coefficient C = 0.8 for all other areas. For example, the luminance control value of the area at position (1, 1) and the area at position (3, 1), which was the minimum luminance control value before correction, is multiplied by 10 (%) by a correction coefficient C = 0.8. 10 (%) × 0.8 = 8 (%), and the brightness control values of the area of the position (1, 3), the area of the position (3, 3), and the area of the position (2, 2) are , 50 (%) is multiplied by a correction coefficient C = 0.8 to be corrected to 50 (%) × 0.8 = 40 (%), and the area of position (1,2) and position (3,2) The brightness control value of the area and the area of position (2, 1) is corrected to 20 (%) × 0.8 = 16 (%) by multiplying 20 (%) by the correction coefficient C = 0.8.

  In the flowchart of FIG. 2, in step S <b> 6, brightness control is performed on each LED light source of the backlight 10 using the corrected LED backlight control map. In the control map before correction, the brightness of the area that should be brightly displayed is simply increased based on the image data, and the brightness of the area that should be darkly displayed is decreased. Therefore, the stimulus value is too high and the image is displayed. At times, there was a risk of adverse effects on human eyes. On the other hand, by controlling the luminance of the backlight 10 using the corrected control map, the stimulus value is equal to or less than the threshold value, so that an image can be displayed so as not to adversely affect human eyes. it can.

  FIG. 8 is a diagram showing a stimulus value map 42 before correction and a stimulus value map 42a after correction. FIG. 8A shows a stimulus value map 42 before correction, and FIG. 8B shows a stimulus value map 42a after correction. In the stimulus value map 42 before correction, the stimulus value in the area at the position (2, 3) was 2400 exceeding the threshold value, but in the stimulus value map 42a after correction, the stimulus value in the area at the position (2, 3). Has fallen to 1920 which is the same as the threshold value.

  In this way, by correcting the LED backlight control map, it is possible to realize a display device that suppresses stimulation given to human eyes without reducing the contrast ratio.

  It should be noted that the corrected stimulus value map 42a shown in FIG. 8B is only shown so that the effect of the present invention can be easily understood, and need not be created in the LED backlight control processing of the present invention.

  Next, another embodiment of the present invention will be described. In the above embodiment, the stimulus value is compared with the threshold value in the stimulus value map, and if a stimulus value that exceeds the threshold value is set, the stimulus value is assumed to be harmful to human eyes. The brightness control value is corrected so as to be equal to or less than the threshold value.

  As a stimulus that adversely affects the human eye, not only a case where a light amount exceeding a certain level is irradiated but also a case where the change in the light amount is steep is conceivable. Therefore, in the present embodiment, a change in the stimulus value in a certain period is detected, and when the change amount is larger than the threshold value, the luminance control value is corrected so that the change amount becomes smaller.

  Here, the fixed period is, for example, 1/60 second which is the same as the update period of the LED backlight control map. A change in the stimulus value during this fixed period is detected, and the amount of change is compared with a predetermined threshold value. If the stimulation value is calculated at least at the start and end of a certain period, two stimulation values can be obtained, and the amount of change can be obtained from the difference between the obtained stimulation values. Note that the fixed period does not necessarily have to be 1/60 seconds, and may be longer. When the frame update period, which is the update period of one frame of image data, is shorter than a certain period, there may be a case where three or more stimulus values are obtained in the certain period, but in this case, it is obtained in the certain period. The maximum value and the minimum value are extracted from all the stimulus values, and the change amount can be obtained from the difference between them.

  For example, it is assumed that the threshold value of the change amount is “500” and the stimulus value changes from “200” to “1000” in a certain period. The amount of change in the stimulus value in a certain period is 1000−200 = 800, and the amount of change “800” exceeds the threshold value “500” as compared with the threshold value. Therefore, it is necessary to correct the luminance control value. to decide. The correction may be performed by calculating a correction coefficient and multiplying the luminance control value by the correction coefficient so that the stimulation value is reduced to the same value as the threshold value, as in the above embodiment. In the above example, since the threshold value of the change amount is “500”, “1000” that is the stimulus value after the change is reduced to 200 + 500 = 700. The brightness control value correction coefficient is calculated by decreasing the brightness control value so that the stimulus value is changed from “1000” to “700”. The correction coefficient was calculated by paying attention to one area where the amount of change exceeds the threshold. If the amount of change exceeds the threshold in a plurality of areas, the area with the largest amount of change was selected and selected. The correction coefficient is calculated so that the change amount of the stimulation value of the area is equal to or less than the threshold value. It is also preferable to correct other areas using the same coefficient as the correction coefficient calculated by paying attention to one area.

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Image | video extraction part 3 Display setting extraction part 4 LED backlight control map creation part 5 Stimulus value map creation part 6 LED backlight control map correction | amendment part 7 Visual protection condition database 8 Display control part 9 Display panel 10 Backlight 20 Video transmission unit 30 Display setting transmission unit 40, 40a LED backlight control map 41 Pixel value map 42, 42a Stimulus value map

Claims (3)

A display unit having a display screen on which an image based on image data composed of a plurality of pixels is displayed;
A light-emitting device that is provided for each region obtained by dividing the display screen and includes a plurality of light-emitting units that display images on the display screen by emitting light toward the corresponding regions;
Luminance control for determining the luminance control value of the plurality of light emitting units for each of the areas according to the image displayed on the display screen, and controlling the luminance of the plurality of light emitting units based on the determined luminance control value And
Whether or not to correct the determined brightness control value is determined for each area based on the pixel value of the pixel corresponding to the image displayed in the area and the determined brightness control value corresponding to the area. A determination unit to
When the determination unit determines that the determined luminance control value is to be corrected for at least one of the regions, the determined luminance control value is corrected, and the corrected luminance control value is transmitted to the light emission luminance control unit. And a correction unit that controls the luminance of the plurality of light emitting units based on the display device.   The determination unit calculates a stimulus value indicating screen brightness in the region based on a pixel value of a pixel corresponding to an image displayed in the region and the determined brightness control value corresponding to the region. 2. The calculated stimulus value is compared with a predetermined threshold value, and if the calculated stimulus value is larger than the threshold value, it is determined that the determined brightness control value is corrected. Display device.   The correction unit, when it is determined that the determined luminance control value is corrected, performs correction of the determined luminance control value using the same correction coefficient for all regions. 2. The display device according to 2.

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