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.