Abstract: In view of the drawbacks of traditional spatial image enhancement algorithms, this paper proposes an improved algorithm based on the layered difference representation (LDR) algorithm which constructs a two-dimensional histogram containing the spatial context information. The histogram exploits the visual characteristics to construct a two-dimensional visual difference histogram, which is consequently used in the enhancement of the input images with LDR. Finally, the grayscale compensation method is used to ameliorate the over-enhancement problem. Experimental results show that the proposed algorithm produces better visual effects (performance), improves the overall brightness and contrast, and eliminates the artifacts. The proposed method is free of parameter selection and meets the real-time processing requirement.

Key words: image enhancement, two-dimensional visual difference histogram, visual characteristic, gray scale compensation