Brightness preserving and non-parametric modified bi-histogram equalization for image enhancement

Zhijun Yao, Zhongyuan Lai, Chun Wang

Abstract: This paper presents a new image enhancement method by histogram equalization called Brightness Preserving and Non-parametric Modified Bi-histogram Equalization (BPNMBHE). Our method consists of three steps: (i) The input original image is divided into two sub images using the average intensity value. (ii) We use the histogram modification technique to maximize entropy and control over enhancement. (iii) Two sub images are enhanced by the traditional histogram equalization method independently and then are merged into one output enhanced image. The experimental results show that BPNMBHE is better than other contrast enhancement methods according to image subjective evaluation and various image objective evaluation measures, i.e. Entropy, PSNR, AMBE, and SSIM.