Abstract
Exposure is critical in the imaging process, since if the lighting condition is poor, the quality and visibility of images will be severely degraded. In this paper, we propose a fully automatic image enhancement algorithm that can efficiently solve the under-exposed problem. The basic idea behind this method comes from the common technique of photography: the exposure compensation. For poorly exposed images like nighttime images and backlit images, they usually have under exposed regions that directly cause the loss of detail visibility. In order to enhance the badly-exposed image, we first decomposed the image into the lightness and reflection components, and then each of it will be further enhanced separately. We examine the under exposed regions and by adapting the photographic Zone theory to determine the level of exposure at each pixel. Every pixel afterwards is enhanced by the concept of exposure compensation. Besides, the image contrast and edge details are also improved by enhancing the reflection layer. The experiments demonstrate that the proposed algorithm is more effeteness than the other comparatives, which not only include more nature color and visible details, but also induce less unpleased artifacts. In addition, the proposed work can be applied on much more variation cases of badly-exposed images without any manually parameter setting. We also show the efficiency of this work that can be expected for real-time application.