Patent ID: 7200270

Claim:
A pattern recognition apparatus for comparing an image which captured a recognition object, with a pre-registered model; and thus recognizing said recognition object, the apparatus comprising: image input means for inputting an image which captured said recognition object; feature point extraction means for extracting multiple feature points from said inputted image; feature point selection means for selecting a combination of multiple feature points from said extracted feature points; basis calculation means for calculating, from said multiple selected feature points, bases which represent the positions and positional relations of these feature points; partial pattern extraction means for extracting from said image a partial pattern of said recognition object corresponding to each of said calculated bases; table storage means for storing a table which includes a plurality of registration places as divided based on index parameters including at least a parameter invariant to geometric transformation derived from the calculated bases, and on which a partial pattern of said model is registered in one of the table registration places corresponding to an index parameter related to the partial pattern and derived from the calculated bases; index search means for deciding a registration place on the stored table, based on an index parameter corresponding to the partial pattern extracted by said partial pattern extraction means; and pattern similarity calculation means for judging the similarity between the partial pattern of said model registered in said decided registration place on the table and the partial pattern extracted by said partial pattern extraction means, wherein the calculated bases are an angle between two basis vectors and a ratio between lengths of the two basis vectors.