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 5:
5. The method of claim 1 wherein step (d) performs the modulation of one or several features among grayscale values, color values and halftone patterns, within a complete character/symbol or only some of its parts, according to the following scheme: (a) grayscale modulation for documents printed in grayscale or color, at low, medium or high printing and/or acquisition resolution when the user defines the selected reproduction principle, (b) color modulation documents printed in color, at low, medium or high printing and/or acquisition resolution, (c) halftone patterns modulation for sufficiently low-resolution printing and sufficiently high-resolution acquisition, (d) 1, 2 or 3 attributes among grayscale, color and halftone modulation being adapted to be used jointly, either to embed a single watermark, or to embed several independent watermarks simultaneously.