Proposed Algorithm for Image Enhancement in Frequency domain

Abstract

This paper presents an algorithm for gray-scale image enhancement in the frequency domain using Discrete Cosine Transform (DCT) depending on the definition of contrast measure in the DCT domain. This algorithm introduces an efficient method for brightening darkened regions of images (which result from bad lighting scenes) without saturation of the normal regions. The proposed algorithm divides the image into nonoverlapping (8×8 pixel) blocks, for each block, the enhancement factor is computed by using a proposed equation. The enhancement factor is varied according to the mean of the block. The blocks with a low mean (dark blocks), get a high enhancement factor while the brightened blocks get a low enhancement factor.