The two algorithms, absolute difference and cross correlation are compared in theory and in computing time based on the fact that the lunar surface is low contrast and extended source.

• 接着，针对月面为低对比度扩展光源这一特点，在理论上讨论了实时分离大气倾斜量的互相关函数法和绝对差分算法的算法原理和运算量的比较。