Patent Document ID: 7644281
Application ID: 10949318

Base Claim:
1. A method for embedding a digital watermark w into textual and/or vector graphics documents of electronic and/or hard-copy form, based on the modulation of luminance or grayscale values, of color values, and/or of halftone patterns of characters and/or of vector elements, the method comprising the steps of (a) encoding a digital message m, resulting into a codeword c; spatially allocating the codeword c, resulting into a watermark signal w suitable for text and/or vector graphics modulation, (b) parsing the original input document in electronic format x in order to isolate all its components, (c) selecting text and/or vector graphics components x text which will carry the watermark w and parsing components x text in order to select single entities or elements to use to encode individual w symbols; and keeping the remaining non selected components x non-text for later document recomposition, (d) modulating the grayscale attributes, the color attributes and/or the halftone pattern attributes of the selected elements in the selected text and/or vector graphics components x text , (e) recomposing the document from the marked version of selected components x text and the remaining components x non-text , resulting into a watermarked document y, which can be stored, distributed, and/or used in electronic form as electronic document {hacek over (y)} a or in printed form as hard copy document {hacek over (y)} b .

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Claim 2:
2. The method of claim 1 wherein step (a) comprises encrypting the digital message m depending on an encryption key k enc , and/or encoding the message depending on an auxiliary key k aux , and/or spatially allocating the codeword c depending on k aux and/or with interleaving of a pilot sequence also depending on k aux ; wherein the method uses any encryption and/or any encoding to generate the codeword c; wherein it uses any spatial allocation to generate the watermark signal w, using symbols from any alphabet either binary or of higher cardinality; wherein it uses any error correcting coding (ECC) comprising each member of the group formed of Bose-Chaudhuri-Hochquenghem (BCH) codes, Reed-Solomon (RS) codes, low density parity check (LDPC) codes, Turbo codes, multilevel-code (MLC), or trellis coded modulation (TCM), or even direct encoding without encryption and/or without ECC; wherein it uses any framework of communication with side information.