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 (not shown). 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.