1. An image recognition system for recognizing correspondence between object images contained respectively in two images obtained by two imaging means, the image recognition system comprising: corresponding pattern-extracting means for setting one of the two images obtained by the two imaging means to a reference image and the other of the two images to a comparison image, calculating a correlation parameter indicative of a correlation between a reference pattern contained in the reference image and containing an object image, and each pattern contained in the comparison image and identical in shape to the reference pattern, by using a luminance value indicative of a luminance of the reference pattern and a luminance value indicative of a luminance of each pattern contained in the comparison image, and extracting, based on the calculated correlation parameter, a pattern having a highest correlation with the reference pattern from the comparison image, as a corresponding pattern which corresponds to the reference pattern; and identity-determining means for determining identity between the object image contained in the reference pattern and an object image contained in the corresponding pattern based on a difference between a contrast value indicative of a contrast of the reference pattern and a contrast value indicative of a contrast of the corresponding pattern.