A lattice dividing unit determines lattice lines to divide parameters of all points of a picture at every division and supplies distortion correction parameters (distortion correction coordinates) on the lattice points to a distortion correction memory. A polynomial of degree n coefficient deriving unit expresses all distortion correction coordinates on each lattice line in the form of a function relative to positions on lattice lines and approximates the distortion correction coordinates by desired division polynomial of degree n. Further, a sample point deriving unit compresses distortion correction parameters based upon the division polynomial of degree n obtained from the polynomial of degree n coefficient deriving unit. In the derived division polynomial of degree n, internal points which result from dividing both ends of the division polynomial of degree n by n is supplied to the distortion correction memory as new distortion correction parameters (approximated distortion correction coordinates). Thus, a memory capacity of a required memory can be reduced in the image processing for correcting distortion of an image.