Segment selective dynamic histogram equalization for brightness preserving contrast enhancement of images.

Abstract: Histogram equalization (HE), is a simple and less complex technique for image contrast enhancement, but it fails to preserve their brightness and natural appearance. It usually introduces visual artifacts due to saturation and un-even expansion of intensities. This paper proposes a novel modification of HE method, which decomposes the histogram of the input image into multiple segments utilizing median values as thresholds. Prior to equalization process, segments having high probability regions are identified and allocated with new dynamic range, while other segments remain unaltered. In order to reduce the algorithmic complexity, the HE is applied over selected segments instead of complete histogram. Finally combination of equalized and un-equalized segments are normalized. Simulation results show that for wide-range of test images, the proposed method enhances contrast while preserving the brightness and natural appearance of the images. [Copyright &y& Elsevier]