Abstract: A method for securely transacting a transaction based on a transaction document having an image contained within the document, the method includes the steps of compressing an image on the document; scrambling the structure of the compressed image according to a permutation; obtaining the inverse permutation; applying the inverse permutation to the scrambled image for obtaining an unscrambled image; and decompressing the unscrambled image.

Abstract: A method for securely transacting a transaction based on a transaction document having an image contained within the document, the method includes the steps of compressing an image on the document; scrambling the structure of the compressed image according to a permutation; obtaining the inverse permutation; applying the inverse permutation to the scrambled image for obtaining an unscrambled image; and decompressing the unscrambled image.

Abstract: A method of encoding and decoding a transaction card with a block of image data digitally representing the features of a digital portrait of an authorized transaction card user is disclosed along with apparatus for performing the method. The encoding method partitions the digital portrait of the transaction card user into feature blocks. Each feature block is compared against a library of like feature blocks to determine the best match with a pair of library feature blocks. The library's feature blocks are derived from a plurality of portraits taken from the general population. Each library feature block is represented (addressed for access) by a code-vector in a codebook.