A device for image processing includes a video signal receiver, for receiving at least one video signal, wherein an image frame of the at least one video signal includes: a plurality of pixel groups; a color engine; and an output stage, coupled to the color engine, for outputting the adjusted at least one video signal. The color engine includes: a local adjusting unit, configured to locally adjust at least one of color hue, luminance factor and saturation of a specific pixel group of the pixel groups without adjusting any other pixel group of the pixel groups, wherein the specific pixel group has color hue in a predetermined range that is a part of a full range of color hue; and a global adjusting unit, configured to globally adjust at least one of color hue, luminance factor and saturation of each of the pixels of the image frame.