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AssigneeCanon Kabushiki Kaisha
InventorsIoana Donescu, Eric Nguyen, Patrice Onno
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A method of determining a partition into distinct regions of a set of coefficients representative of at least a part of an image in order to insert a watermark comprises the following steps: generation (E501) of a centred pseudo-random sequence (w) equal in size to the cardinal number (N) of the said set of coefficients, formed from centred pseudo-random sub-sequences; modulation (E502) of the said set of coefficients by the said centred pseudo-random sequence (w) in order to insert the same information bit on the said set of coefficients; and checking (E504–E508), over each region, of a criterion of detectability of the information bit inserted by modulation. Use especially for determining an adaptative partition as a function of a criterion of detectability of an information bit inserted on each region.
Method of inserting, into a digital image, a watermarking signal (W) by modulating coefficients (X) of distinct spatial regions (R) representing said digital image (I), comprising a step of determining a partitioning into distinct spatial regions of the digital image, characterised in that the partitioning into regions is effected by adaptively selecting for each information bit, a subset of coefficients forming a region to be modulated as a function of criterion of statistical detectability of the information bit inserted in the region.
Method of decoding a watermarking signal in a digital image, inserted by modulating coefficients (X) representing said image in distinct spatial regions forming a partitioning of said digital image, characterised in that a partitioning into distinct spatial regions of the digital image to be decoded is effected by adaptively selecting for each information bit, a subset of coefficients forming a region to be demodulated as a function of a criterion of statistical detectability of the information bit obtained by demodulating coefficients of the region.
Device for inserting, into a digital image, a watermarking signal (W) by modulating coefficients (X) of distinct spatial regions (R) representing the digital image (I), characterised in that it comprises partitioning means adapted to adaptively select for each information bit, a subset of coefficients forming regions to be modulated as a function of a criterion of statistical detectability of the information bit inserted in the region.
Device for decoding a watermarking signal in a digital image, inserted by modulation of coefficients representing said image in distinct spatial regions forming a partitioning of said digital image, characterised in that it comprises means for partitioning the digital image to be decoded into distinctive spatial regions, adapted to adaptively select for each information bit, a subset of coefficients forming regions to be demodulated bit as a function of a criterion of statistical detectability of the information bit obtained by demodulating coefficients of the regions.
Method of inserting, into a digital image, a watermarking signal (W) by modulating coefficients (X) of distinct spatial regions (R) representing said digital image (I), comprising a step of determining a partitioning into distinct spatial regions of the digital image, wherein the partitioning into regions is effected by selecting, for each information bit, a subset of coefficients forming a region to be modulated, the size of said region being a function of criterion of statistical detectability of the information bit inserted into the region.
Method of inserting, into a digital image, a watermarking signal (W) by modulating coefficients (X) of distinct spatial regions (R) representing said digital image (I), comprising a step of determining a partitioning into distinct spatial regions of the digital image, wherein the partitioning into regions is effected by selecting, for each information bit, a subset of coefficients forming a region to be modulated, the size of said region depending on a given detection probability of the information bit inserted in the region.
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