The invention relates in particular to a stream-wise method of watermarking independent of the compression parameters used (for example type of the transform) so as to allow the reading of the watermarking inserted independently of the format of the data received. The watermarking method according to the invention consists in generating a contribution matrix in the transformation space, in projecting it into another domain and in watermarking the data in this domain on the basis of the projected matrix so as to allow a watermark reader operating in the transformed transformation space to read back the inserted watermarking in the transformation space. The contribution matrix representing the modifications induced on the coefficients in the transformation space by insertion of the watermarking cue in this same domain.