A method for improving image quality in an image processing device comprises receiving an image signal comprising a plurality of field signals corresponding to a plurality of fields, each field signal comprising a plurality of pixel signals corresponding to a plurality of pixels, and each pixel signal comprising an original chrominance value and a compensating chrominance value; replacing the compensating chrominance value of a pixel signal in every field signal by the original chrominance value of another pixel signal of a same position in another field signal, and generating a primary compensating result corresponding to every pixel signal; calculating a primary weighted sum of a pixel signal corresponding to every pixel and a primary compensating result corresponding to the pixel signal according to a degree of variation corresponding to every pixel of every field; and outputting the primary weighted sum corresponding to every pixel, to output primary compensating field signals.