关键词: 图像增强, 直方图均衡化, 子直方图均衡化, 直方图修正, 变分技术, 局部直方图均衡化, 梯度域, 小波域

Abstract: Equalization is equal to uniform distribution, image enhancement algorithms directed by the equalization ideology have rich connotation, profound significance, wide application. Histogram Equalization（HE） is representative strongly in the field of image enhancement, on the basis, in recent years, researchers have expanded the applications of equalization ideology in the field of image enhancement. However, there is lack of the reviewing paper about HE for image enhancement which can comprehensively summarize HE related techniques, this paper considers the equalization ideology as the mainline, the improved work is classified into 5 kinds of techniques, meanwhile, the typical algorithms of each technique are analyzed, finally, the probable research directions in future are pointed out.

Key words: image enhancement, histogram equalization, sub-histogram equalization, histogram modification, variation technique, local histogram equalization, gradient domain, wavelet domain