Hardcopy watermarking
AssigneeHewlett-Packard Development Company, L.P.
InventorsAvraham Levy, Doron Shaked
Life of this patent
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Abstract
A digital image is hardcopy watermarked by modifying transform coefficients in a transform domain representation of the digital image, the transforms coefficients being modified according to bit values of an n-bit message. A message in a hardcopy watermarked image is identified by statistically decoding a transform domain representation of the watermarked image.
Claims30
A method of hardcopy watermarking a digital image with a message, the method comprising modifying a plurality of transform coefficients in a transform domain representation of the image, the transform coefficients being modified according to bit values of the message.
A method of identifying a message in a transform domain representation of a scanned hardcopy watermarked image, the method comprising statistically decoding the message in the transform domain representation.
The method of claim 10, wherein statistics parameters are based on an ordering of coefficients within selected coefficient pairs, and wherein each bit of the decoded message depends on the ordering of the coefficients within a corresponding coefficient pair.
Apparatus for hiding a message in a hardcopy image, the apparatus comprising a processor for modifying a plurality of transform coefficients in a transform domain representation of the image, the transform coefficients being modified according to bit values of the message.
Apparatus for estimating a message in a transform domain representation of a scanned hardcopy watermarked image, the apparatus comprising a processor for statistically decoding the message in the transform domain representation.
Software for a processor, the software comprising a plurality of instructions for instructing the processor to hardcopy watermark an image by modifying a plurality of transform coefficients in a transform domain representation of the image, the transform coefficients being modified according to bit values of the message.
Software for a processor, the software comprising a plurality of instructions for instructing the processor to decode a degraded version of a hardcopy watermarked image by statistically decoding a message in a transform domain representation of the degraded version of the image
A system comprising:
- an encoder for hardcopy watermarking a digital image with a message by modifying a plurality of transform coefficients in a transform domain representation of the image, the transform coefficients being modified according to bit values of the message;
- and
- a decoder for statistically decoding the message in a transform domain representation of a degraded version of the image.
Dependencies are inferred from the claim text.