An image processing method applied to an image processing system. The image processing method comprises: (a) computing an image intensity distribution of an input image; (b) performing atmospheric light estimation to the input image; (c) performing transmission estimation according to a result of the step (a) to the input image, to generate a transmission estimation parameter; and (d) recovering scene radiance of the input image according to a result generated by the step (b) and the transmission estimation parameter. At least one of the steps (a)-(c) are performed to data corresponding to only partial pixels of the input image.