Color Clipping and Over-exposure Correction

Abstract

Limitations of the camera or extreme contrast in scenes can lead to clipped areas in captured images. Irrespective of the cause, color clipping and over-exposure lead to loss of texture and detail, impacting the color appearance and visual quality of the image. We propose a new over-exposure and clipping correction method, which relies on the existing correlation between RGB channels of color images to recover clipped information. Using a novel region grouping approach, clipped regions are coherently treated both spatially and temporally. To reconstruct over-exposed areas where all channels are clipped we employ a brightness profile reshaping scheme, which aims to preserve the appearance of highlights, while boosting local brightness. Our method is evaluated using objective metrics as well as a subjective study based on an ITU standardized protocol, showing that our correction leads to improved results compared to previous related techniques. We explore several potential applications of our method, including extending to video as well as using it as a preprocessing step prior to inverse tone mapping.