Research On The Method Of Image Quality Evaluation Based On LCD Backlight Partitions

Now,the display focuses on the direction of wide color gamut,high dynamic range,high resolution,low power consumption,large and micro.LCD,as a mature,low-cost,low-power,wide range of practical display,has occupied the mainstream of the display market for a long time,but one of the disadvantages of LCD is that the dynamic range is not high,facing the challenges of new display technologies such as OLED.In order to solve this problem,the ultrahigh backlight area(ULED)technology of local dimming has been applied,and the BD Cell LCD and multi area Mini LED backlight LCD have been put into the market successively.The main purpose of this paper is to explore the relationship between the number of backlight partitions and image quality.The main work,innovations and achievements are as follows:Firstly,based on the dynamic backlight technology,this paper discusses three methods to realize the LCD dynamic backlight system.Considering the stability of the system and the flexibility of adjusting the number of backlight partitions,the dynamic backlight display system of the stacked LCD is selected as the experimental platform.Based on the problem of simulating backlight source,a backlight simulation method based on Lambert cosine law is proposed.This method can simulate the backlight diffusion phenomenon of LED array on the experimental platform,and get the backlight simulation data image of the image.Secondly,aiming at the partition problem of LCD backlight in high dynamic range,the visual perception experiment is designed to study the influence of backlight partition and image quality,and the optimization rule of limit partition is obtained.In this experiment,12 images with different content and brightness are selected.Each image corresponds to 21 different backlight partitions.The subjects can judge the quality of the image compensated by the backlight in different regions and get the threshold of the backlight limit region.Thirdly,based on the key characteristic index of image quality evaluation,the influence of LCD backlight on image quality is analyzed.In order to further analyze whether it will continue to improve the image quality to increase the backlight partitions after the image quality reaches good,this paper evaluates the images compensated by different backlight based on the key characteristic indexes of image quality evaluation: Peak Signal-to-Noise Ratio,Structural Similarity and Luminance,and concludes that when the image quality reaches good,further increasing the backlight partitions will improve the image characteristics not much.Finally,in view of the problem that the backlight of LCD will affect the image texture,this paper evaluates the image texture characteristics after different backlight compensation based on the gray level co-occurrence matrix.It is concluded that increasing the number of backlight partitions can significantly improve the texture quality of the image when the number of backlight partitions is small,and further increasing the backlight region will produce Moirépattern and reduce the contrast of the image when the number of backlight partitions is large,which has a slight effect on the texture characteristics of the image.