Estimation of lighting conditions based on near-gray pixel detection using cylindrical boundaries

摘要

This disclosure describes image processing techniques that facilitate the determination of the lighting condition associated with an image. Once the lighting condition is determined, white balance can be performed on the image such as by applying white balance gains defined for the lighting condition. According to the techniques of this disclosure, gray point lines are defined and plotted for the different lighting conditions, and cylindrical bounding volumes are defined around the gray point lines, e.g., in a three-dimensional color space. The image is then analyzed with respect to each of the cylindrical bounding volumes to determine how many pixels of the image fall within the respective cylindrical bounding volumes formed around the gray point lines for the different lighting conditions. Based on this analysis, the actual lighting condition can be determined. The use of cylindrical bounding volumes can significantly improve the process of determining lighting conditions relative to conventional techniques.