Cloud shadow removal from aerial photographs

摘要

Aerial photographs may contain extremes in brightness variation due to the presence of cloud shadows. The variations will at times be beyond the dynamic range of photographic media, and as a result, either the non-shadowed regions will be severely overexposed or the shadowed regions will be severely underexposed. This paper describes a computer image processing solution for this dilemma. It first identifies the cloud-shadowed regions, and then carries out brightness compensation on the shadowed regions to achieve an image with seemingly uniform illumination. Illustrations are included to demonstrate the effectiveness of the cloud shadow removal technique.