Digital Watermarking of Natural Images Based on LPTV Filters
Vincent Martin, Marie Chabert, B. Lacaze · 2007
In this paper, linear periodically time varying (LPTV) filters are used as an alternative to direct sequence modulation in spread spectrum watermarking techniques. Due to their periodicity, LPTV filters combined with a Peano-Hilbert scan in the spatial domain of natural images offer good decoding performance. Specific LPTV filters are proposed to reject the low-pass host noise and to shape the watermark spectrum. Extensions to improved spread spectrum and quantization in a subspace projection are also investigated.