A plurality of images (I, J) of an object (M) when viewed from different viewpoints are taken in. One of the images is set as a standard image (I), and the other image is set as a reference image (J). One-dimensional pixel data strings with a predetermined width (W) are cut out from the standard image (I) and the reference image (J) along epipolar lines (EP1, EP2) calculated from a camera parameter (CPR) and the reference point (p). Calculating a phase-only correlation function from the cut one-dimensional pixel data strings will obtain a correlation peak position (Pa1). A positional shift amount (d) from the correlation peak position (Pa1) is obtained. A search is made for a corresponding point (q) corresponding to the reference point (p) based on this position shift amount (d).