1. An image processing method, comprising: providing a current image, wherein the current image comprises a plurality of image blocks, and each of the image blocks has a plurality of pixels; subtracting a first block of the image blocks of the current image by the first block of at least one previous image for obtaining a difference block; performing a motion detection process to the difference block for determining whether the first block of the current image is in a static state; and performing a temporal filtering process to the first block of the current image and the first block of the previous image if the first block of the current image is in the static state so as to output the processed first block of the current image.