An image-quality improvement method is provided. The image-quality improvement method includes detecting an area of interest from an input image; generating a color distribution map based on a plurality of respective brightness elements and a plurality of respective chroma elements of a plurality of pixels which belong to a predetermined color series and which are in the detected area of interest of the input image; determining a first area, which belongs to the predetermined color series, and a second area, which is an area of the input image other than the first area, according to the color distribution map; and changing values of a plurality of pixels in at least one of the first area and the second area.