Improving Iterative Retinex Algorithm For Dynamic Range Compression

In this paper, the iterative Retinex algorithm is improved to handle dynamic range compression problems. Based on the analysis of the McCann-Sobel algorithm, the iterative smoothing operation can be interpreted as an asymmetric diffusion. In order to characterized the sharp discontinuities in illumination, an edge-stopping function is introduced into the iterative procedure, which is inspired by anisotropic diffusion. Using the improved illumination estimator, dynamic range of images can be arbitrarily manipulated while suppressing undesirable artifacts. Experiments show that the proposed algorithms outperforms several derivatives for dynamic range compression based on the iterative Retinex.