Backlight control method and backlight control device

The invention discloses a backlight control method and a backlight control device, and belongs to the technical field of screen display. The method comprises the steps of: acquiring gray-scale values of pixels of an image to be displayed in each display block of a screen, wherein the screen comprises at least one display block; according to the gray-scale values of the pixels, acquiring a minimum value from a preset number of maximum gray-scale values; and when the minimum value reaches the gray-scale threshold value, controlling the gray-scale values of the pixels to remain unchanged, and controlling the backlight luminance of the display block to remain the maximum backlight luminance. By using the backlight control method, a problem that image contrast is greatly reduced and the image display effect is greatly influenced by using a content adaptive backlight control (CABC) technology when the image is processed is solved; and when the image has the pixel with the high gray-scale value, the image is not processed by CABC, so that the damage to the image contrast is reduced, and the image quality and the display effect are improved.