Patent ID: 6944313

Claim:
A method of inserting a supplementary information item (S), in a digital image (I), characterized in that it includes the following steps: multi-resolution spectral breakdown (E 1 ) of the digital image at a number (d) of breakdown levels dependent on image size and determined so that a lowest frequency sub-band has a number (n) of components of lowest frequency comprised between 8×8 and 32×32; extraction (E 2 ) of the components of the lowest frequency sub-band; choice (E 3 ) of a subset of the components consisting of only components in the lowest frequency sub-band; modulation (E 4 ) of only the components of the subset consisting of only components in the lowest frequency sub-band in order to insert the supplementary information item (S); and reverse multi-resolution spectral recomposition (E 5 ) of the watermarked digital image (I′).