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US 6,788,801 B2Granted
Cocktail watermarking on images
AssigneeAcademia Sinica
InventorsHong-Yuan Mark Liao, Chun-Shien Lu
Life of this patent
Estimating the term…
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.
Claims11
The method for detecting information embedded in an image comprising:
- accepting an image;
- transforming the accepted image to form a plurality of transform coefficients 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, wherein determining the plurality of estimates comprises determining a positive watermark estimator that estimates a positive watermark used to modify a subset of transform coefficients of the original image such that the magnitude of each of the coefficients is more likely to be increased than decreased.
6 more elements
The 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 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 water mark sequence;
- and
- determining an overall indicator that the watermark sequence was encoded in the accepted image from the plurality of indicators determining the plurality of estimates comprises determining a negative watermark estimator that estimates a negative watermark used to modify a subset of transform coefficients of the original image such that the magnitude of each of the coefficients is more likely to be decreased than increased.
6 more elements
A method comprising:
- generating an indicator to indicate whether a watermark sequence is in an accepted image based on an estimate of a positive watermark in the accepted image and an estimate of a negative watermark in the accepted image,
- the positive watermark being used to modify a subset of transform coefficients of an original image such that the magnitude of each of the transform coefficients is more likely to be increased than decreased, and
- the negative watermark being used to modify a subset of transform coefficients of the original image such that the magnitude of each of the transform coefficients is more likely to be decreased than increased.
Dependencies are inferred from the claim text.