A liquid crystal display has the advantages of high resolution, light in weight, low energy consumption, and so on. Therefore, it has been widely used. In the LCD, the light emitted from the backlight layer enters the liquid crystal layer after passing through the first polarizing filter layer. When liquid crystal molecules are affected by an external electric field, they will produce an accurate and orderly alignment. When the electrode in the LCD generates an electric field, the liquid crystal molecules are twisted, so that the light passing through the liquid crystal molecules is regularly refracted and then displayed on the screen through the second polarizing filter layer. However, the twist of the liquid crystal molecules requires a process, and if the response time of the liquid crystals is greater than the interval of the frame, the screen may have a smear when people watch a fast moving picture.
In order to solve the problem of smear, the overdrive technique is used to improve the response speed of the LCD. The overdrive technique shortens the response time of the liquid crystals by increasing the driving voltage. The principle is that an overdrive circuit is provided in the TCON (Timer Control Register) board of the liquid crystal display. The overdrive circuit needs to store a previous frame image. The overdrive circuit needs to store the previous frame image and compare it with the gray scale value of the current frame image, and then calculate the gray scale compensation value required for the current frame by querying the overdrive lookup table. The gray scale compensation value (equivalent to the supplied drive voltage), so that the displayed gray scale value is the target value within a prescribed time. In addition, when the overdrive circuit stores the previous frame image, the previous frame image is first compressed and then stored in order to save costs. Therefore, the compression algorithm (hereinafter referred to as overdrive compression algorithm) used by the overdrive circuit will directly affect the picture quality. Therefore, it is necessary to verify the overdrive compression algorithm to ensure the display quality of the picture.