the resulting shortest path is used as the signature further reference to viterbi decoding algorithms and trellis diagrams may be had to u201c list viterbi decoding algorithms with applications u201d ieee transactions on communications vol 42 no 2 3 4 1994 pages 313 322 hereby incorporated by reference one way to generate the n real numbers is to perform a wavelet decomposition of the image and to use the resulting coefficients of the lowest frequency sub band these coefficients are then used as the n real numbers for the viterbi decoding e g to generate a signature or hash one way to map a larger set of numbers m to an n bit hash where m gt n and m and n are integers is to use trellis coded vector quantization where the algorithm deals with sets of real numbers rather than individual real numbers the size and complexity for a resulting signature may be significantly reduced with such an arrangement in step 62 fig6 the initial signature e g hash is stored in a database preferably the signature is associated with a content id which is associated with a desired behavior information or action in this manner a signature may be used to index or locate additional information.