1. An image processing method, comprising: performing an edge detection upon image data of a current frame to generate an image edge detection result; determining an adjusting parameter corresponding to a target pixel according to the image edge detection result; calculating a gray value difference between a gray value of the target pixel in the current frame and a gray value of the target pixel in a previous frame; and adjusting the gray value of the target pixel in the current frame according to the adjusting parameter and the gray value difference, wherein calculating a product of the adjusting parameter and the gray value difference; determining a ratio parameter; multiplying the product by the ratio parameter to generate an adjusted product; and summing up the adjusted product and the gray value of the target pixel in the current frame to generate an adjusted gray value of the target pixel in the current frame.