In optical information processing,the very tiny differences and minutiae in an image can be enlargeded by the image derivations and pseudo-color codes,which have different advantages. In this paper,combining the two methods,a new method is proposed. Firstly,an image is coded by a grating Secondly a white light sourse is used,and the space frequency of the image is filtered in 4F optical system. Then the image derivations and pseudo-color codes on an image with successively changing greyness are realized simultaneously.The proposed method with changeable derivation can process large areas and offer rich color image. With this new method,the pictures such as the CT pictures are easily analyzed forexample.