PURPOSE: To provide the picture processor which easily collates and recognizes even a picture transformed by rotation, enlargement/reduction, or the like.

CONSTITUTION: A picture input means 1 which irradiates coherent light of approximately parallel rays to input a picture into an optical system and a computer hologram 3 which superposes phase information for desired coordinate transformation on picture information inputted into the optical system by the picture input means are provided. Further, a Fourier transform lens 4 for fourier transforming picture information on which phase information is superposed by the computer hologram, a coordinate transforming surface 5 placed in the focal position in the rear side of the Fourier transform lens, and a detecting means 6 which detects coordinate transform information outputted to the coordinate transforming surface are provided, and coordinate transform information letting the transform range in the direction of an angle θ of coordinate transform be 4π is obtained.