1. An image processing apparatus, comprising: motion vector detection means for detecting a motion vector of each of a plurality of blocks of a predetermined size set in an image and formed from a plurality of pixels; and global motion calculation means for carrying out convergence mathematical operation, from the motion vectors of the blocks detected by said motion vector detection means, using extended affine transformation in which at least one of affine parameters is represented by a function of a variable regarding a displacement axis of the image to calculate a global motion representative of deformation applied to the entire image.