Regionally optimized image contrast enhancement

This study proposes a new adaptive image enhancement algorithm based on contrast-tone mapping curves. In the proposed method, an image is divided into several blocks and a histogram is calculated for each block. An appropriate mapping curve is calculated from the shape of the histogram for each block and quasi-regional contrast enhancement can be obtained. The experimental results demonstrate that the performance of the proposed method is very similar to that of the Retinex method, whereas the computational time required is much lower than that with the Retinex method. This technique can be applied to consumer electronics devices such as digital cameras and smartphones.