Method and device for watermarking an image
First Claim
1. A method of inserting a watermark composed of a plurality of binary information in an image comprising at least three components, the method comprising of:
- decomposing at least one component of the image into detail sub-bands in various directions and comprising coefficients, each coefficient being characterized by its position in the detail sub-band to which it belongs and its amplitude;
determining, for each position, information representing local amplitude variations in various directions from amplitudes of the coefficients at the position in the various detail sub-bands and coefficients close to the position in the various detail sub-bands;
determining, a watermarking strength at each position from information representing local amplitude variations in various directions determined for the position;
forming, for each position and for each decomposed component, a vector whose coordinates are the amplitudes of the coefficients at the position in the various detail sub-bands of the component;
selecting, for each position, one vector amongst the vectors formed for the position;
watermarking the image by modifying, for each position, the amplitude of the coefficients which are the coordinates of the vector selected for the position according to the binary information corresponding to the position and according to the watermarking strength determined for the position.
1 Assignment
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Accused Products
Abstract
The invention concerns a method of inserting a watermark in an image comprising at least three components, the method comprises the steps of decomposing at least one component of the image into detail sub-bands in various directions and comprising coefficients, each coefficient being characterized by its position in the detail sub-band to which it belongs and its amplitude, of determining, for each position, information representing local amplitude variations from the amplitudes of the coefficients at this position in the various detail sub-bands and the coefficients close to this position in the various detail sub-bands, of determining a watermarking strength at each position from the information representing determined local amplitude variations in the said position and inserting a watermark composed of a plurality of binary information in the image, inserting each item of binary information at a position on the image according to the watermarking strength determined for a position corresponding to the position at which the binary information is inserted.
13 Citations
14 Claims
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1. A method of inserting a watermark composed of a plurality of binary information in an image comprising at least three components, the method comprising of:
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decomposing at least one component of the image into detail sub-bands in various directions and comprising coefficients, each coefficient being characterized by its position in the detail sub-band to which it belongs and its amplitude; determining, for each position, information representing local amplitude variations in various directions from amplitudes of the coefficients at the position in the various detail sub-bands and coefficients close to the position in the various detail sub-bands; determining, a watermarking strength at each position from information representing local amplitude variations in various directions determined for the position; forming, for each position and for each decomposed component, a vector whose coordinates are the amplitudes of the coefficients at the position in the various detail sub-bands of the component; selecting, for each position, one vector amongst the vectors formed for the position; watermarking the image by modifying, for each position, the amplitude of the coefficients which are the coordinates of the vector selected for the position according to the binary information corresponding to the position and according to the watermarking strength determined for the position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 13)
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8. A method of detecting a signature inserted in an image comprising at least three components, comprising the steps of:
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decomposing at least one component of the image into detail sub-bands in various directions and comprising coefficients, each coefficient being characterized by its position in the detail sub-band to which it belongs and its amplitude; determining, for each position, information representing local amplitude variations in various directions from amplitudes of the coefficients at this position in the various detail sub-bands and coefficients close to this position in the various detail sub-bands; forming, for each position and for each decomposed component, a vector whose coordinates are the amplitudes of the coefficients at the position in the various detail sub-bands of the component; determining, for each position, a vector comprising some binary information amongst the vectors formed for the position, and determining of inserted binary information; detecting the signature from at least some binary information inserted in a plurality of positions in the image and information representing local amplitude variations in various directions corresponding to the binary information. - View Dependent Claims (9, 10, 14)
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11. A device for inserting a watermark composed of a plurality of binary information in an image comprising at least three components, the device comprising:
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means of decomposing at least one component of the image into detail sub-bands in various directions and comprising coefficients, each coefficient being characterized by its position in the detail sub-band to which it belongs and its amplitude; means of determining, for each position, information representing local amplitude variations in various directions form amplitudes of the coefficients at the position in the various detail sub-bands and coefficients close to the position in the various detail sub-bands; means of determining a watermarking strength at each position from information representing local amplitude variations in various directions determined for the position; means of forming, for each position and for each decomposed component, a vector whose coordinates are the amplitudes of the coefficients at the position in the various detail sub-bands of the component; means of selecting, for each position, one vector amongst the vectors formed for the position; means of watermarking the image by modifying, for each position, the amplitude of the coefficients which are the coordinates of the vector selected for the position according to the binary information corresponding to the position and according to the watermarking strength determined for the position.
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12. A device for detecting a signature inserted in an image comprising at least three components, the device comprising:
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means of decomposing at least one component of the image into detail sub-bands in various directions and comprising coefficients, each coefficient being characterized by its position in the detail sub-band to which it belongs and its amplitude; means of determining, for each position, information representing local amplitude variations in various directions from amplitudes of the coefficients at this position in the various detail sub-bands and coefficients close to this position in the various detail sub-bands; means of forming, for each position and for each decomposed component, a vector whose coordinates are the amplitudes of the coefficients at the position in the various detail sub-bands of the component; means of determining, for each position, a vector comprising some binary information amongst the vectors for the position, and determining of inserted binary information; means of detecting the signature from at least some binary information inserted in a plurality of positions in the image and information representing local amplitude variations in various directions corresponding to the binary information.
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Specification