Patent ID: 6272246
Filing Date: 2001-08-07
Classification: G06K,G06T

Abstract:
A positioning device, which carries out a positioning between a preliminarily registered reference image and a newly inputted target image, comprising:a first calculating section for calculating features of the target image;a first gradation conversion section which converts the gradation of the target image so as to produce a rough target image based upon the results of calculations in the first calculating section so that information related to contrast of the target image is contained to a greater extent, and so that the number of density levels of the target image is reduced;a rough search section for finding the degree of similarity between a rough reference image whose gradation has been converted and the rough target image so as to find a maximum matching candidate point; anda precise search section for finding a maximum matching point between the reference image and the target image in the proximity of the maximum matching candidate point, wherein the first calculating section is a first maximum-value calculating section for calculating a maximum value of densities of the target image, and the first gradation conversion section generates the rough target image by linearly converting the density levels of the target image in a rate corresponding to the maximum value.