Histogram modification and DCT based contrast enhancement

In this paper, a new contrast image enhancement algorithm is proposed. The algorithm is based on new approach for histogram modification, and a DCT based enhancement algorithm. Most of the histogram based approaches suffers from the problem of over enhancement and under enhancement. This works addresses the said issue by proposing a new approach for histogram modification. The algorithm modifies the histogram by devices a sigmoid based function. The resulting images are further improved by applying an DCT based algorithm for local contrast enhancement. The algorithm is test on large set of images and compared with existing algorithms. The quantitative and visual analysis of the resulting images shows the proposed algorithm performs comparatively better than many existing algorithms.