Tjahjadi T & Dale-Jones R

Machine Graphics and Vision, vol 5, no 3, 1996, 503-519

Abstract

This paper presents two global contrast enhancement algorithms which take into account the display capabilities of the monitor where the image is viewed. The algorithms approximately space out the grey level bins in the image histogram according to the results of two psychophysical experiments, which determine the ability of the eye to distinguish the Just Noticeable Difference (JND) between grey levels for different monitors. The look-up-table of JNDs of a monitor is used to ensure that the enhanced image will appear the same on different monitors. The first algorithm assumes that there is only one background in the image and separates the grey level bins close to the background intensity. The second algorithm considers the largest bin within the grey level range of each of the identified regions in the image to be the background intensity, and separates the bins on either side of each background.