Patent ID: 8855421

Claim:
A method of identifying an indexed image, the method comprising: receiving a first image containing an index indicator; conducting a first comparison of the first image with candidate indexed images, the conducting the first comparison comprising constructing a first representation of the first image in which the first image is represented with a grid having a first resolution, representing each of the candidate indexed images with a grid having the first resolution, and identifying the number of matching correspondences between grid locations of the first representation and the corresponding grid locations of each of the candidate indexed images; conducting a first ranking of the candidate indexed images based on the number of matching correspondences of the first comparison; selecting candidate indexed images based on the first ranking; conducting a second comparison of the first image with the selected candidate indexed images, the conducting the second comparison comprising creating a second representation of the first image in which the first image is represented with a grid having a second resolution higher than the first resolution, representing each of the selected candidate indexed images with a grid having the second resolution, and identifying the number of matching correspondences between grid locations of the second representation and the corresponding grid locations of each of the selected candidate indexed images; conducting a second ranking of the selected candidate indexed images based on the number of matching correspondences of the second comparison; and identifying the indexed image based on the second ranking.