20090180152, "UV encryption via intelligent halftoning," assigned to Xerox.
Abstract
A method for encryption of a digital watermark by intelligent halftoning includes receiving image data that define at least a portion of a document to be printed in terms of at least three halftone images corresponding respectively to three printing colorants, each of the three halftone images comprising a plurality of halftone cells. The image data are modified by phase-shifting some of the halftone cells of at least one of the halftone images relative to the other halftone images to encode a watermark within the portion of the document such that the at least one phase-shifted halftone image includes a phase-shifted region and a non-phase-shifted region. The modified image data are used to print the portion of the document on a substrate that will fluoresce when subjected to UV illumination. The printed portion of the document includes a first printed pattern resulting from the phase-shifted region and a second printed pattern resulting from the non-phase-shifted region. The first and second patterns of the printed portion of the document appear substantially similar when the portion of the document is viewed in visible light, and appear dissimilar when the portion of the document is viewed in UV light such that the watermark encoded in the modified image data is perceptible when the portion of the document is viewed in UV light and is hidden when the portion of the document is viewed in visible light.
20090182997, "System and method for detecting [fingerprint code words], assigned to Sony Great Britain (UK)
Abstract
A system for recovering an estimate of a finger print code word from an un-authorised copy of content material includes a content packaging apparatus. The content packaging apparatus includes a secure content production device and a proxy generator. The secure content production device is operable to convert the content material into a content data file for distribution to a reproduction apparatus, the content data file including frames of the content material which are to be reproduced by a reproduction apparatus and to encrypt the content data file using a content encryption key to form a secure content data file for secure distribution to the reproduction apparatus. The proxy generator is operable to generate a proxy version of the content material representing a reduced quality version of the content material, the quality being reduced to discourage unauthorised copying of the content material and including the frames of the content material which are to be reproduced by the reproduction apparatus. The proxy generator is operable to record the proxy version of the content onto a carrying medium. The reproduction apparatus is operable to decrypt the secure content file to recover the content material, to introduce one or more finger print code words into the frames of the content to form a marked version of the content, and to reproduce the marked content. A detection device is operable to receive the carrying medium and to receive a suspected unauthorised copy of the marked content reproduced by the reproduction apparatus, and to reproduce the proxy version of the content from the carrying medium. The reproduced version of the proxy version of the content has the same frames of the content as produced by the reproduction of the content by the reproduction apparatus. The detection device is operable to recover an estimate of the one or more finger print code words by comparing the frames of the proxy version with the frames of the suspect version. Embodiments of the present invention seek to provide an arrangement in which a proxy version of the content material can be generated and distributed to finger print code word detection devices to facilitate detection of the fingerprint code words and thus the payload provided in those fingerprint code words.
