1. A display apparatus, comprising: a receiving circuit for receiving and processing an incoming signal to generate an image signal; an image processing circuit, coupled to the receiving circuit, for processing the image signal and generating a driving signal; a display unit, coupled to the image processing unit and driven by the driving signal to display contents of the image signal; a luminance analysis circuit, coupled to the receiving circuit, for analyzing the image signal and generating a luminance analysis result; a backlight module for irradiating the display unit; and a backlight controller, coupled to the luminance analysis circuit and the backlight module, for generating a control signal according to the luminance analysis result to control the backlight module.