A contrast restoration method for effective single image rain removal algorithm

This paper introduces an efficient rain removal algorithm by including the contrast restoration method. Since the rain streaks in rainy image exist in the high frequency parts, many conventional rain removal algorithms first decompose the input rainy image into the base (low-frequency) layer and the detail (high-frequency) layer and then perform rain removal on the detail layer rather than on the entire image. However, the conventional algorithms have a problem that they cannot remove the contrast variation. For this reason, our method also considers the contrast enhancement on the base layer. We further estimate and eliminate the contrast variation on the base layer by low-pass filtering the approximated rain streaks. Although the low frequency components contain not only the contrast variation but also the basic information of the image, our method can distinguish the contrast variation from the base layer and remove them automatically. Visual and quantitative experiments demonstrate our approach has the high efficiency and outperforms previous rain removal algorithm.