Cocktail watermarking on images
AssigneeAcademia Sinica, a research institute in Taiwan
InventorsHong-Yuan Mark Liao, Chun-Shien Lu
Life of this patent
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Abstract
A novel image protection scheme named “cocktail watermarking” improves over current spread-spectrum watermarking approaches. Two watermarks, which play complementary roles, are simultaneously embedded into an original image. The new watermarking scheme has the characteristic that, no matter what an attack is, at least one watermark typically survives well and can be detected. Results of extensive experiments indicate that our cocktail watermarking scheme is effective in resisting various attacks.
Claims7
A method for adding information to a first image comprising:
- transforming the first image to form a plurality of transform coefficients which represent said first image;
- selecting a first subset of the transform coefficients;
- modifying each of the first subset of transform coefficients such that the magnitude of each of the coefficients is more likely to be increased than decreased;
- selecting a second subset of the transform coefficients;
- modifying each of the second subset of transform coefficients such that the magnitude of each of the coefficients is more likely to be decreased than increased;
- and
- forming a second image using the modified first subset of transform coefficients and the second subset of transform coefficients
A method for detecting information embedded in an image comprising:
- accepting an image;
- transforming the accepted image to form a plurality of transform coefficient which represent the accepted image;
- accepting an original image;
- transforming the original image to form a plurality of transform coefficients which represent the original image;
- computing a difference between the transform coefficients of the original image and the transform coefficients of the accepted image;
- determining a plurality of estimates of a watermark sequence, each estimate being determined from a different subset of the computed differences between transform coefficients;
- computing a plurality of indicators that the watermark sequence was encoded in the accepted image, each indicator being associated with a different one of the determined estimates of the watermark sequence;
- and
- determining an overall indicator that the watermark sequence was encoded in the accepted image from the plurality of indicators.
Dependencies are inferred from the claim text.