Abstract: Histogram equalization techniques are used for enhancing images. The aim of an image enhancement is to improve the quality of the image for better visualization. This paper presents implementation of three methods of histogram equalization namely BHE, DHE and BPDFHE taking a common dataset using MATLAB platform. Moreover the performance of above mentioned techniques has been evaluated on the basis of visual results and objective image quality parameters namely PSNR, RMSE, AD, SC and MD. A comparative analysis has been carried out and it has been observed that for gray level images, BHE and DHE introduce impractical and improbable effects in the enhanced images. However the BPDFHE technique overcomes this limitation by fuzzifying the weight of histogram region to avoid contouring.

Keywords: Histogram Equalization, Image Enhancement, MD, PSNR, SC, RMSE and Visual Quality.