A method of and an apparatus for enhancing digital image quality. Input color data are transformed to obtain brightness data and chrominance data. The transformed brightness data is compared with predetermined brightness levels X1 and X2 on a pixel by pixel basis and the brightness data of each concerned pixel is reset or output without change according to the comparison. The comparison identifies the concerned pixel as belonging to one of a dark area and a light area requiring contrast enhancement and the brightness level of the concerned pixel is adjusted to provide the enhanced contrast. The obtained chrominance data and the reset brightness data are inversely transformed into corresponding color data. The predetermined brightness levels X1 and X2 are adaptively recomputed after a last pixel in a concerned line is considered for contrast enhancement.