The gray processing of moon digital orthophoto map

Considering the mosaic result of the lunar DOM (Digital Orthophoto Map) produced by China's "CE-1" satellite, there usually exists a sharp gray jump beside the joining line. As to a strip image, the gray distribution may be uneven because of the light changing or position difference during photographing. To solve these matters, a method was proposed which is based on dynamic rules to detect the best joining line, and then stretch image according to its gray histogram. By making the pixels around boundary to change gradually, the joining line will finally be invisible. In order to solve the uneven gray distribution problems causing by imaging angle, light condition and other factors, a homogenization technology based on statistics of gray distribution was proposed. Using statistical information of the bands' longitudinal changes to united the gray level to a defaulted range. The experimental results show that the method of this paper can make the integral gray level become even, the transition become more gently, and visual effect become more natural.