Image enhancement with the preservation of brightness and structures by employing contrast limited dynamic quadri-histogram equalization

Image enhancement has been widely applied to medical science, industry, agriculture, and military, for which it is very important to preserve brightness and structures. In order to overcome the shortcomings of over-enhancement and over-smoothing of traditional histogram equalization methods, this paper proposes an effective image enhancement strategy named as contrast limited dynamic quadri-histogram equalization (CLDQHE) which includes three steps: (1) the original histogram of an image is divided by a proposed threshold scheme into four sub-histograms. (2) An adaptive histogram clipping method is proposed to control the enhancement rate, which can adjust the clipping threshold. (3) Each sub-histogram is mapped to a new dynamic range and is equalized independently. Both quantitatively and qualitatively experimental results demonstrate that the proposed CLDQHE method can yield pleasing results with the preservation of brightness and structures, and even outperforms the state-of-the-arts.

Automated summary

This paper proposes an effective image enhancement strategy called CLDQHE, which overcomes the shortcomings of traditional histogram equalization methods by dividing the original histogram into four sub-histograms and introducing an adaptive histogram clipping method. Experimental results demonstrate that the proposed CLDQHE method yields pleasing results and even outperforms the state-of-the-arts.