TWI672978B - Back light adjusting method and display device for local dimming - Google Patents

Abstract

The present invention provides a method for adjusting a backlight of a region dimming, which is suitable for a display device. The display device includes a display panel and a backlight module, and the backlight module includes a plurality of light emitting units. The method for adjusting the backlight includes: acquiring an image, and dividing the image into a plurality of blocks, wherein the blocks respectively correspond to the above-mentioned light-emitting units; for each of the light-emitting units, calculating a light-emitting intensity according to the brightness value of the pixels in the corresponding block And for each block, determine whether the number of pixels whose brightness value is greater than a brightness threshold is greater than a threshold value, and if so, the illumination intensity corresponding to the block is greater than or equal to the first intensity threshold.

Description

Regional dimming backlight adjustment method and display device

The present invention relates to a backlight adjustment method, and more particularly to a backlight adjustment method and display device for local dimming.

In general, liquid crystal display devices include a backlight module. Conventional backlight modules use a fixed backlight, and in order to increase the contrast, local dimming technology must be used, which is regionally The backlight brightness of a specific portion is adjusted according to the distribution of image brightness. For example, when a brighter area of an image is displayed, the backlight outputs a high brightness; when a darker area of the image is displayed, the output brightness of the backlight is attenuated. Thereby, the display with regional dimming control has higher dynamic contrast and lower power consumption. However, when area dimming is used, some images with special patterns have unexpected effects, so it is necessary to detect these patterns and perform corresponding processing.

An embodiment of the present invention provides a method for adjusting a backlight of a region dimming, which is applicable to a display device. The display device includes a display panel and a backlight module, and the backlight module includes a plurality of light emitting units. The backlight adjustment method includes: acquiring an image, and dividing the image into a plurality of blocks, wherein the image includes a plurality of pixels, wherein the blocks respectively correspond to the light emitting unit; and for each of the light emitting units, according to the brightness of the pixels in the corresponding block Calculating a luminous intensity; and for each of the blocks, determining whether the number of pixels whose brightness value is greater than a brightness threshold is greater than a threshold value, and if so, setting the luminous intensity corresponding to the block to be greater than or equal to the first intensity threshold .

In some embodiments, the step of setting the illumination intensity corresponding to the block to be greater than or equal to the first intensity threshold comprises: determining whether the illumination intensity is less than the first intensity threshold, and if so, setting the illumination intensity to be the first intensity threshold, otherwise maintaining The luminous intensity does not change.

In some embodiments, the step of setting the illumination intensity corresponding to the block to be greater than or equal to the first intensity threshold comprises: determining whether the illumination intensity is less than a second intensity threshold, and if so, increasing the illumination intensity by a nonlinear function, otherwise maintaining the illumination The intensity is unchanged.

In some embodiments, the minimum value of the range of values of the nonlinear function is greater than or equal to the first intensity threshold, and the first intensity threshold is less than the second intensity threshold.

In some embodiments, the step of calculating the illumination intensity from the luminance values of the pixels in the corresponding block comprises calculating the illumination intensity from an average of the luminance values of the pixels in the corresponding block.

In another aspect, an embodiment of the present invention proposes a The display device comprises a display panel, a backlight module and a logic circuit. The backlight module includes a plurality of light emitting units. The logic circuit is used to obtain an image and divide the image into a plurality of blocks, wherein the image includes a plurality of pixels, and the blocks correspond to the light emitting units respectively. For each of the light emitting units, the logic circuit calculates the light emission intensity based on the brightness values of the pixels in the corresponding block. For each block, the logic circuit determines whether the number of pixels whose luminance value is greater than a luminance threshold is greater than a threshold value, and if so, sets the illumination intensity corresponding to the block to be greater than or equal to the first strength threshold.

In some embodiments, the logic circuit determines whether the illumination intensity is less than the first intensity threshold, and if so, sets the illumination intensity to the first intensity threshold, otherwise the illumination intensity remains unchanged.

In some embodiments, the logic circuit determines whether the illumination intensity is less than a second intensity threshold, and if so, increases the illumination intensity by a non-linear function, otherwise the illumination intensity is maintained.

In some embodiments, the minimum value of the range of values of the nonlinear function is greater than or equal to the first intensity threshold, and the first intensity threshold is less than the second intensity threshold.

In some embodiments, the logic calculates the illumination intensity from the average of the luminance values of the pixels in the corresponding block.

In the method and display device provided by the embodiments of the present invention, a special pattern can be detected and the illumination intensity can be adjusted, thereby improving the quality of the display.

The above described features and advantages of the invention will be apparent from the following description.

100‧‧‧ display device

110‧‧‧ display panel

120‧‧‧Backlight module

130‧‧‧Logical Circuit

121~128‧‧‧Lighting unit

201, 202‧ ‧ images

Block 301~308‧‧‧

311, 312‧‧ ‧ Highlights

320‧‧‧Compensated images

330‧‧‧ images

T ₁ , T ₂ ‧‧‧ intensity threshold

510‧‧‧ Curve

601~607‧‧‧Steps

FIG. 1 is a schematic view showing a display device according to an embodiment.

FIG. 2 is a schematic diagram showing an image with a special pattern according to some embodiments.

FIG. 3 is a schematic flow chart showing an area dimming mechanism according to an embodiment.

[Fig. 4] and [Fig. 5] are diagrams showing a conversion function of luminous intensity according to an embodiment.

FIG. 6 is a diagram illustrating a backlight adjustment method for area dimming according to an embodiment.

The terms "first", "second", "etc." used in this document are not intended to mean the order or the order, and are merely to distinguish between elements or operations described in the same technical terms.

FIG. 1 is a schematic diagram showing a display device according to an embodiment. Referring to FIG. 1, the display device 100 can be a screen or any electronic device including a screen, such as a smart phone, a tablet, a notebook, and the like. The display device 100 includes a display panel 110, a backlight module 120, and a logic circuit 130.

The display panel 110 can be any suitable liquid crystal display panel, for example, fringe field switching (FFS), coplanar Display panels such as in-plane switching (IPS) mode, twisted nematic (TN), and vertical alignment (VA).

The backlight module 120 includes a plurality of light emitting units 121-128. The light emitting units are, for example, light emitting diodes (LEDs). By controlling the brightness of the light emitting diodes, local dimming can be implemented. Mechanisms. However, the number and arrangement positions of the light-emitting units 121-128 in FIG. 1 are merely examples. In other embodiments, the backlight module 120 may have more or fewer light-emitting units, and the light-emitting units may have other set positions. In FIG. 1 , the light-emitting module 120 is a direct-lit light-emitting module, but in other embodiments, it may be an edge-lit light-emitting module, as long as there are multiple light-emitting units to be different. The area provides light sources of different intensities, all within the scope of this specification.

The logic circuit 130 is used to acquire an image, and after performing some image processing procedures on the image, the image is provided to the display panel 110 for display. The logic circuit 130 can also control the luminous intensity of each of the light emitting units 121 to 128. The logic circuit 130 is, for example, a timing controller, but may be any wafer or circuit in the display device 100 in other embodiments. The backlight adjustment method explained below is performed by the logic circuit 130, and will not be described below.

2 is a schematic diagram of an image with a particular pattern, in accordance with some embodiments. In Fig. 2, images 201 and 202 are shown, and these images have bright stripes or dots, and the background brightness is low. Under the conventional regional dimming mechanism, these stripes or dots may be caused by the illumination of the light-emitting unit. The intensity is dimmed and becomes invisible or invisible. Specifically, FIG. 3 is a schematic flow chart showing an area dimming mechanism according to an embodiment. In FIG. 3, the image 202 is taken as an example. For convenience of illustration, the bright spots 311, 312 in FIG. 3 are drawn in black, and the background is white, but it should be understood that the image 202 in FIG. 3 is in FIG. The image 202 is the same. In this embodiment, the image 202 is a color image, for example, including three channels of red, green, and blue. In other words, each pixel includes three grayscale values corresponding to red, green, and blue. The luminance value of each pixel is calculated below, which in some embodiments is the maximum of the three grayscale values of red, green, and blue, but in some embodiments, the three may also be used. The grayscale value is converted to another color space and the luminance value therein is obtained, such as the intensity in the HIS color space or the luminance value Y in the YCbCr color space. However, those skilled in the art will be able to adopt luminance values in any color space, and the present invention is not limited thereto.

After the image 202 is acquired, the image 202 is divided into a plurality of blocks 301 to 308, and the blocks 301 to 308 correspond to the light-emitting units 121 to 128 in the light-emitting module 120, respectively. For each of the light-emitting units, one light-emission intensity can be calculated according to the brightness value of the pixel in the corresponding block. For example, for the light-emitting unit 122, the average value of the luminance values of all the pixels in the area 302 and the histogram can be calculated, and the luminous intensity can be calculated according to the average value and the histogram. In general, the average of the luminance values is directly proportional to the illumination intensity, so in some embodiments only the average of the luminance values in region 302 can be calculated and this average is linearly mapped to obtain the illumination intensity. In some embodiments, the grayscale value and the luminance value are 8 bits, and the luminous intensity is 12 bits, but the invention is not limited thereto. In addition to the above calculation methods, in other Any algorithm for calculating the luminous intensity can also be employed in the embodiment, and the present invention is not limited to the above embodiments. It is to be noted that since the average value of the luminance of the pixels in the regions 301 and 308 is small, the luminous intensity of the light-emitting units 121 and 128 is also small.

After calculating the luminous intensity, the image 202 can be compensated to obtain the compensated image 320. For example, since the illumination intensity of the illumination unit 122 is weak (below the illumination intensity without the regional dimming mechanism), the luminance value can be increased for pixels within the region 302, and so on. However, the present invention also does not limit how to generate the compensated image 320.

Finally, the compensated image 320 is transmitted to the display panel 110, and the light source emitted by the light emitting module 120 can visually present the image 330. As described above, since the light-emitting intensity of the light-emitting units 121, 128 is small, the bright spots 311, 312 are not seen in the image 330 (or become dark and unclear). In this embodiment, it is determined whether or not the special pattern is present in the image 202, thereby adjusting the luminous intensity.

Specifically, for each of the blocks 301 to 308, it can be determined that the brightness value of several pixels in the block is greater than a brightness threshold, and it is determined whether the number of the pixels is greater than a threshold value. The brightness threshold is, for example, 200, and the number threshold can be adjusted according to the size of the block, and the present invention does not limit the value of the brightness threshold and the number threshold. If the number of pixels whose luminance value is greater than the luminance threshold is greater than the threshold value, the illumination intensity of the corresponding illumination unit may be appropriately increased, otherwise the illumination intensity is maintained. In the embodiment of Fig. 3, the luminous intensity of the light-emitting units 121, 128 is increased, while the luminous intensity of the other luminous units is maintained.

In some embodiments, even if the above judgment is met, if the corresponding luminous intensity is not low, it is not necessary to increase the luminous intensity. Specifically, after a certain block meets the above determination regarding the brightness value, it may be further determined whether the illumination intensity of the corresponding illumination unit is less than a first intensity threshold, and if so, the illumination intensity is set to be the first intensity threshold. Otherwise, the luminous intensity is maintained. This adjustment can refer to FIG. 4, the horizontal axis represents emission intensity before adjustment, and the vertical axis is the emission intensity after adjustment, can be seen from Figure 4 that the emission intensity will be adjusted intensity is greater than a first threshold value T _1. In other embodiments, when a certain block meets the above judgment regarding the brightness value, it may be further determined whether the corresponding luminous intensity is less than a second intensity threshold, and if so, the luminous intensity is increased by a nonlinear function, otherwise The luminous intensity does not change. Referring to FIG. 5, when the luminous intensity before the adjustment is smaller than the second intensity threshold T ₂ , the luminous intensity is increased by a nonlinear function (corresponding to the curve 510), and the nonlinear function may be an exponential function or a polynomial. Function, the invention is not limited thereto. In some embodiments, the minimum value of the range of the nonlinear function may be set to be greater than or equal to the first intensity threshold T ₁ , such that the adjusted luminous intensity is greater than or equal to the first intensity threshold. T ₁ . It should be noted that the first intensity threshold T ₁ is smaller than the second intensity threshold T ₂ , but the present invention does not limit the two threshold values. According to the above method, the special pattern in FIG. 2 can be detected and the luminous intensity can be increased, whereby these bright spots and bright stripes can be seen on the display panel.

FIG. 6 illustrates a backlight adjustment method for area dimming according to an embodiment. Referring to FIG. 6, in step 601, an image is obtained, and the image is divided into a plurality of blocks, and the blocks correspond to a plurality of light-emitting sheets in the backlight module. yuan. In step 602, for each of the light-emitting units in the backlight module, a luminous intensity is calculated according to the brightness value of the pixel in the corresponding block. In step 603, it is determined whether the number of pixels whose luminance value is greater than a luminance threshold in a block is greater than a threshold value. If the result of step 603 is no, the corresponding illumination intensity is maintained unchanged in step 604. If the result of step 603 is yes, in step 607, it may be set that the illumination intensity corresponding to the block is greater than or equal to the first intensity threshold. For example, in step 605, it may be further determined whether the corresponding illumination intensity of the block is less than the first intensity threshold. If the result of step 605 is no, step 604 is performed as well. If the result of step 605 is YES, in step 606, the luminous intensity is set to the first intensity threshold. In the embodiment of FIG. 6, step 607 is implemented with the conversion curve of FIG. 4, but in other embodiments step 607 can also be implemented with the conversion curve of FIG. The steps in Fig. 6 have been described in detail above, and will not be described again here. It should be noted that the steps in FIG. 6 can be implemented as multiple code codes or circuits, and the present invention is not limited thereto. In addition, the method of FIG. 6 can be used in conjunction with the above embodiments, or can be used alone. In other words, other steps can be added between the steps of FIG. 6.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

Claims (4)

A method for adjusting a backlight for a region dimming is applicable to a display device. The display device includes a display panel and a backlight module. The backlight module includes a plurality of light emitting units. The backlight adjusting method includes: acquiring an image. And dividing the image into a plurality of blocks, wherein the image includes a plurality of pixels, the blocks respectively corresponding to the light emitting units; for each of the light emitting units, according to the corresponding ones in the blocks Calculating a luminous intensity of the brightness value of the pixel; and determining, for each of the blocks, whether the number of the pixels whose brightness value is greater than a brightness threshold is greater than a threshold value, and if so, setting the corresponding block The illuminating intensity is greater than or equal to a first intensity threshold, wherein the step of setting the illuminating intensity corresponding to the block to be greater than or equal to the first intensity threshold comprises: determining whether the illuminating intensity is less than the first intensity threshold, and if so, setting The luminous intensity is the first intensity threshold, otherwise the luminous intensity is maintained. The backlight adjustment method of claim 1, wherein the calculating the luminous intensity according to the brightness values of the pixels in the corresponding block comprises: according to the pixels in the corresponding block The average of the brightness values is used to calculate the luminous intensity. A display device includes: a display panel; a backlight module including a plurality of light emitting units; and a logic circuit for acquiring an image and dividing the image into a plurality of blocks, wherein the image includes a plurality of pixels The blocks correspond to the light-emitting units respectively. For each of the light-emitting units, the logic circuit calculates a light-emitting intensity according to the brightness values of the pixels in the corresponding block, for each of the areas. Block, the logic circuit determines whether the number of the pixels whose brightness value is greater than a brightness threshold is greater than a threshold value, and if yes, sets the light intensity corresponding to the block to be greater than or equal to a first intensity threshold, where The logic circuit determines whether the luminous intensity is less than the first intensity threshold, and if so, sets the luminous intensity to the first intensity threshold, otherwise the luminous intensity is maintained. The display device of claim 3, wherein the logic circuit calculates the luminous intensity according to an average of the brightness values of the pixels in the corresponding block.