An image processing method used for enhancing the color saturation of an image is provided. The image comprises a pixel with a pixel data, wherein the pixel data has the data of three colors. The image processing method comprises the steps stated below. Firstly, a color purity of the pixel is calculated and a corresponding scale factor is generated according to the color purity, wherein the color purity is the difference between the maximum grayscale value and the minimum grayscale value of the data of the three colors. Then, a processed pixel data is generated according to an enhancement matrix and the pixel data, wherein the enhancement matrix is determined by the scale factor.