LOSSLESS SPATIAL FEATURE DESCRIPTOR COMPRESSION

A computer-implemented method includes receiving a spatial feature descriptor representing a binary string of comparison results between specified pairings of N patches in a region of an image, N being an integer greater than one. The method further includes compressing the spatial feature descriptor by determining a minimum number of bits needed to represent N, and generating a sorted array representing a ranking of the N patches based on the binary string of comparison results. Each element of the sorted array is associated with a corresponding patch of the N patches and stores a value representing a ranking of the patch relative to the other N−1 patches and coded using the minimum number of bits needed to represent N. The sorted array may be further compressed using a progressive bit representation decimation process.