CONTRAST ENHANCEMENT USING MODIFIED ERROR DIFFUSION

摘要

This paper proposes a contrast enhancement (CE) algorithm combined with modified error diffusion (ED). After simple histogram equalization (HE), artefacts such as false contours are produced in the enhanced image. The proposed CE algorithm using modified ED consists of two parts: CE and ED. In the first part, a low-contrast input image is enhanced by the conventional HE method. In the second part, we use the modified ED algorithm. The inputs of the second part are the average and scaled difference images of the original input image and the HE image, in which the scaled difference image is diffused by the ED algorithm. In the proposed algorithm, the modified ED algorithm reduces the artefact produced in the HE image, and increases the number of intensity grey levels. Computer simulations with a number of low-contrast images show the effectiveness of the proposed CE method in terms of the visual quality as well as the probability mass function. It can be used as a post-processing for CE with simultaneous artefact reduction in various display devices.