Target region-aware tone reproduction

In this paper, we propose an automatic tone reproduction scheme. This scheme enhances the visual details of an image´s low contrast regions, while preserving the details of high contrast regions. Our method first segments an image into a number of clusters based on luminance information. Subsequently, our scheme calculates the local variation of each cluster. Using the set of computed local variations, we obtain an adaptive gain factor of each pixel to make details of the image visible. With this adaptive gain factor, our method can directly enhance low contrast regions without affecting high contrast ones. The experimental results demonstrate that our method is superior to many existing algorithms, especially when testing on images that contain both high and low contrast regions. The reason behind these results is clear: most tone reproduction algorithms recover the details of low contrast regions, but simultaneously suppress the high contrast regions. Our algorithm, however, recovers the visual details of low contrast regions without sacrificing the quality of high contrast regions. Most importantly, our proposed automatic tone reproduction scheme eliminates the effort of manual adjustment of parameters.