Design Of LCD Dynamic Dimming Control System Based On Zynq

Currently,Liquid Crystal Display(LCD)has been widely used in various mobile phones,tablets,mobile terminals and other devices.For LCD display equipment,the display power consumption of the LCD screen is the main reason for its power consumption.The LCD generally consists of two parts: liquid crystal display module and backlight module.The liquid crystal display module is responsible for displaying the image,while the backlight module is responsible for the brightness level of the display screen.At present,in most display devices with LCD,the backlight module maintains a constant brightness,so the system consumes too much power when displaying,and the image display quality is easily decreased due to light leakage.The above-mentioned problems can be effectively solved by adjusting the backlight brightness of LCD screen adaptively through dynamic dimming algorithm.In this thesis,an adaptive dimming algorithm is proposed for embedded mobile display devices.Based on the Field Programmable Gate Array Zynq platform,a corresponding backlight adjustment control system is designed and implemented.The main research contents of the thesis are as follows.1)State-of-the-art technologies about LCD display,backlight adjustment and image display processing platform are analyzed.Targeting at the problems existing in current backlight adjustment algorithms,the corresponding solution is given in this thesis.Moreover,the structure and display principle of the LCD,and dynamic dimming principle as well,are given.In addition,the software and hardware platforms required for system design and development are profiled.2)An image content-based adaptive dimming algorithm(ICADA)is proposed to solve the problems in the existing algorithms.Firstly,the contribution degree of high-brightness pixels is defined to describe the importance of high-brightness pixel details in the image,according to the mean brightness value and the maximum brightness value of the input image;meanwhile,the backlight brightness is dynamically adjusted on the basis of the mean brightness value.Then,taking the arithmetic square root of the ratio of brightness values before and after dimming as the ?parameter,an adaptive Gamma compensation method is presented to compensate pixels of the image.The performance of the proposed algorithm is evaluated subjectively and objectively by means of Matlab simulation.Experimental results show that ICADA can significantly reduce the backlight power consumption of low-brightness images(the power consumption saving rate can reach up to58.159%),improve the image display details and reduce the pixel distortion of high-brightness images (the structural similarity index can reach up to 0.9999).3)The proposed ICADA,pulse width modulation control algorithm for backlight adjustment,and Digital Visual Interface(DVI)decoding algorithm for communication with the host computer are designed and implemented by using hardware description language and high-level design method,and are encapsulated into an IP cores.Then the dynamic dimming control system is designed and implemented utilizeing the IP cores designed,supplemented by some IP cores provided by Xilinx officially.Thereafter,the corresponding test and verification platform are built utilizing Zynq development board AX7020,LCD display module AN870 and PC.Finally,the performance of dimming control system is evaluated using static image and video respectively.Results show that the dimming control system designed can reduce system power consumption and improve image display quality,under the premise of utilizing less system resources.