Show-through watermarking of duplex printed documents

13 years 6 months ago
Show-through watermarking of duplex printed documents
A technique for watermarking duplex printed pages is presented. The technique produces visible watermark patterns like conventional watermarks embedded in paper fabric. Watermark information is embedded in halftones used to print images on either side. The watermark pattern is imperceptible when images printed on either side are viewed independently but becomes visible when the sheet of paper is held up against a light. The technique employs clustered dot halftones and embeds the watermark pattern as controlled local phase variations. Illumination with a back-light superimposes the halftone patterns on the two sides. Regions where the front and back-side halftones are in phase agreement appear lighter in show-through viewing, whereas regions over which the front and back side halftones are in phase disagreement appear darker. The image printed on one side has a controlled variation of the halftone phase and the one printed on the other side provides a constant phase reference. The wat...
Gaurav Sharma, Shen-ge Wang
Added 31 Oct 2010
Updated 31 Oct 2010
Type Conference
Year 2004
Authors Gaurav Sharma, Shen-ge Wang
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