Image enhancement using piecewise transfer functions with segmentations

As digital cameras have become popular in recent years, image enhancement for dark pictures is widely applied in post-processing. We propose a method to not only enhance the contrast entirely with detailed adjustment in small dark areas without producing blocking artifacts, but also improve the contrast of the global view. In order to avoid blocking artifacts, we first segment the original image into several local regions of similar pixel values, and then the new pixel values are determined by a certain weighting of pixel values mapped by global piecewise transfer function of the entire image as well as those (segmented beforehand) mapped by the local piecewise transfer functions, in which the relative weights between the global and local enhancements are allowed to be adjusted so as to preserve the original tone. The experimental results suggest our approach to be promising.