Cocktail watermarking on images

Assignee: Academia Sinica

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Filing: 1999-10-08

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Granted: —

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Expires: 2019-10-08

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Abstract

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 [I(x,y)] (100). The original image (100) is processed by an encoder (110) to mark the image with a so-called watermark to produce a watermarked image [I (m) (x,y)] (130). The watermarked image (130) is distributed, e.g. over the Internet, and may be inadvertently or intentionally modified as represented by attack (150) to produce modified watermarked image [I*(x,y)] (170). A detector (180) processes attacked watermarked image (170), along with other information produced during the encoding phase, such as random watermark sequence [N] (120) and a mapping [m(x,y)] (122) which identifies where in watermarked image (130) watermark sequence (120) is hidden. This other information is not distributed along with the watermarked image, enabling a determination to be made whether the input to detector (180) is indeed a modified version of watermarked image (130). 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.

Inventors

👤 Hong-Yuan Mark Liao
👤 Chun-Shien Lu

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-09 10:51

CPC Classifications

G; G06; G06T; G06T1/00; G06T1/0021; G06T1/005; G06T1/0071; H; H04; H04N; H04N1/00; H04N1/32; H04N1/32101; H04N1/32144; H04N1/32149; H04N1/32154; H04N1/3217; H04N1/32187; H04N1/32288; H04N1/32304; H04N19/00; H04N19/46; H04N19/467; H04N19/60; H04N19/63; H04N21/00; H04N21/20; H04N21/23; H04N21/238; H04N21/2389; H04N21/23892; H04N21/80; H04N21/83; H04N21/835; H04N21/8358; G06T2201/00; G06T2201/005; G06T2201/0052; G06T2201/0081

Claims Analysis

Total Claims: 7

Claim 1

Independent Claim 114 words

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

Claim 2

Dependent Claim 21 words

The method of claim 1 wherein transforming the first image includes computing a plurality of wavelet coefficients from the first image.

Claim 3

Dependent Claim 34 words

The method of claim 2 wherein the magnitude of each of the coefficients in the first and the second subsets is greater than a multiple of a just noticeable difference value for that coefficient.

Claim 4

Dependent Claim 49 words

The method of claim 3 wherein modifying each of the first subset of transform coefficients includes increasing the magnitude of each of said first set of coefficients, and modifying each of the second subset of transform coefficients includes decreasing the magnitude of each of said second set of coefficients.

Claim 5

Dependent Claim 81 words

The method of claim 4 further comprising computing a plurality of random numbers, and wherein increasing the magnitude of each of the first subset of coefficients includes increasing the magnitude of each of said first set of coefficients according to a different one of the random numbers, and wherein decreasing the magnitude of each of the second subset of coefficients includes decreasing the magnitude of each of said second set of coefficients according to a different one of the random numbers.

Claim 6

Dependent Claim 65 words

The method of claim 1 further comprising: accepting a third image; transforming the third image to form a plurality of transform coefficients which represent said third image; computing a difference between the transform coefficients of the first image and the transform coefficients of the third image; determining an indicator that the third image is a processed version of the second image from the computed difference.

Claim 7

Independent Claim 143 words

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.

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