Image enhancement using the modified cosine function and semi-histogram equalization for gray-scale and color images
B. Williams, Chih‐Cheng Hung, K.K. Yen, Todd P. Coleman · 2002
The paper outlines two image enhancement operators for gray scale and color images. A modified cosine function was developed for image enhancement, in which some enhanced images may appear a little darker if the average pixel value in the image generally falls below the intermediate value (which is 128 in most images used in the experiments (256 gray-level)). A Semi-Histogram-Equalization (SHE) method is then proposed for enhancement so that regardless of how dark or bright the image is, it would give a good contrast enhancement. Experimental results show that the proposed operators can enhance gray scale and color images effectively.