In addition to using the aberration correction theory, optical distortion can be corrected with the digital image processing technology. This is suitable to some optical system such as the optical system for endoscope and machine vision, which distortion is difficult to be corrected through normal optical method because of some kind of limitation. Firstly, We discussed the correcting theory by the digital image processing technology. Then, the correcting method was introduced. To assess the accuracy, we analyzed the source of the correction error. And the correction evaluation were proposed to measure the error.