1. A method for correcting color artifact of an image provided by an image system, comprising: providing a plurality of bases, each of the bases providing a basic correction value for each pixel of an intermediate image associated with the image; calculating a plurality of coefficients according to the intermediate image, each coefficient associated with one of the bases; generating a correction map by respectively weighting the bases with the coefficients, and summing the weighted bases; and providing a corrected image by correcting the image according to the correction map.