A method for adjusting color values of a video signal. The video signal includes a first frame and a second frame prior to the first frame. The method includes steps of: determining a motion-level value of a first pixel in the first frame according to color values of the first pixel and a second pixel in the second frame; performing a first filtering operation to obtain an adjusted color value of the first pixel if the motion-level value is smaller than a first threshold; performing a second filtering operation to obtain the adjusted color value of the first pixel if the motion-level value is greater than a first threshold; and performing a third filtering operation to obtain the adjusted color value of the first pixel if the motion-level value lies between the first threshold and the second threshold.