The invention relates to an image processing chip and related method. The image processing chip includes a pin for receiving a composite signal; a synchronization signal detecting circuit, coupled to the pin, for extracting a synchronization signal from the composite signal; a clamping circuit, coupled to the pin, for adjusting a voltage level of the composite signal according to the synchronization signal; and an analog to digital converter, coupled to the pin, for generating a video signal by sampling the composite signal.