Research On Perceptually Optimized Technique For Displayed Image Under Ambient Light

As the display devices, such as projector, outdoor LED display, mobile phones, etc, are widely used in modern life, the requirement of the display quality is becoming increasingly higher.Therefor, it will be of great importance in raising the quality of display image to monitor the changes in ambient light around the screen in real-time, and adjust the parameters of screen accordingly.Affected by the change of ambient light, the brightness and contrast of the outdoor devices would suffer a certain degree of decline, resulting in the display image of color dim and blurred, reducing the appreciation of the entire screen. Aiming at the problem,this paper analyzes the mechanism of the impact of ambient light on the screen based on the response characteristics of the visual system, and devotes to the study of existing perceptually optimized techniques to put forward a new algorithm finally. The specific research contents are as follows:(1)Based on the study of tone mapping, combining with the understanding of human visual characteristics and visual model,a new algorithm that can improve the quality of degraded image caused by the ambient light is proposed in this paper.(2)Analysis the advantages and disadvantages of existing perceptually optimized algorithms, and in order to overcome the shortcomings of them, an optimization algorithm that can improve the perceived quality of display images is put forward. The algorithm simulates the human visual system model, and firstly, it uses a low-pass filter to divide a image into two layers:a base layer and a detail layer. Then,a mapping function,for the purpose of preserving the brightness perception differences of the original image,is used to map luminances of the base layer.Meanwhile, a compensation coefficient of the detail layer was computed according to the change of the base layer,to make the image processed more natural.(3)To overcome the halo artifacts in the region where the illumination changes rapidly,which the proposed algorithm in this paper suffer from,the algorithm that can eliminate the halo artifacts is applied to improve the proposed algorithm based on theanalysis of its mechanism of production.(4)A subjective experiment,achieved by comparing every two algorithms, is designed to verify the validity of the proposed algorithm.And its result shows that, the proposed algorithm has good performance on preserving perceived details,and can bring people the close visual impression as the original image under different ambient light.