Abstract: A sub-pixel disparity cost volume which contains initial cost values of dissimilarity calculated between the pixel values on a standard image of a plurality of parallax images and the interpolated sub-pixel values on the counterpart image or images other than said standard image is prepared for a plurality of parallax images of objects in a three-dimensional structure composed of horizontal, vertical and disparity axes. Noise signals on the calculated cost values in the sub-pixel disparity cost volume are eliminated by using an edge-preserving filter which allocates bigger weights between two cost values whose pixel coordinates have similar pixel values on the standard image, for preserving edges or boundaries of the objects. A sub-pixel disparity is selected, which gives the minimum cost value in the specific disparity range around a previously-given initial pixel-wise or sub-pixel disparity at each pixel coordinate on the standard image.