Research On Local Dimming Algorithm Based On HDR Display

The larger the dynamic range,the stronger the ability to describe the details.The high dynamic range(HDR)is to maximum reproduced the dynamic range of the real scene in the case of hue resolution unchanged.The HDR display devices can bring more layers of pictures for users and more details that SDR display devices cannot see.However,due to the dynamic range mismatch between the input source and the monitor,the SDR display devices cannot fully display the content information of the HDR image/video.In order to achieve HDR display,people devote themselves to developing HDR display device,which has become a research focus in the display technology.The key to developing HDR display device is to improve the dynamic range of LCDs as much as possible,corresponding to the image is to improve its contrast.SDR display devices using global backlight,that is,whether the picture on the screen is white or black,the backlight module is always fully open.This not only caused a great waste of energy,but also serious leakage phenomenon will cause the low contrast in LCDs when the backlight module is fully open.According to the optical theory,the dynamic range of LCDs is the product of the dynamic range of the backlight module and the LCD panel.In order to improve the dynamic range of LCDs as much as possible,LED-backlight local dimming technology was put forward.The LED-backlight local dimming is one of the most promising techniques to enhance the visual quality and contrast ratio of LCDs,and it also can reduce power consumption.This paper aims to study the backlight local dimming algorithm,focusing on solving two major problems.The first one is to improve the dynamic range of LCDs.For this purpose,two novel local dimming algorithms which are based on image content are proposed to improve the contrast of the dimmed image and enhance the display quality.The second one is from the point of view of power consumption and display quality.Considering the relationship of mutual constraint existing between power consumption and display quality,there must be one or more schemes which can get the best display quality when all the schemes' power consumption is less than or equal to a certain value.Meanwhile,there must be also one or more schemes that can get the lowest power consumption when all the schemes achieve a certain display quality.Therefore,the backlight local dimming problem can be regarded as an optimization problem.In this paper,a local dimming algorithm based on swarm intelligence is proposed to improve the display quality and reduce the power consumption.In the proposed algorithm,an improved shuffled frog leaping algorithm is applied to determine the backlight luminance of each block.In this paper,the performance of the proposed algorithms are tested by MATLAB.The simulation results show that the proposed algorithms which are based on image content can effectively improve the image contrast and enhance display quality.And the proposed algorithm which is based on swarm intelligence can improve the display quality and reduce the power consumption.At the same time,the proposed algorithms which are based on image content are tested on our principle prototype.The test results show that the black performance of the prototype is more profound and presents more details.And the brightness is also increased to more realistic brightness performance.What's more,the color layers and definition of the dimmed image have been enhanced.This indicates that the proposed algorithms can effectively improve the dynamic range of LCDs and enhance the display quality.