Patrizio Campisi

Wavelet-based method for high-frequency subband watermark embedding

In this paper a novel wavelet based robust blind watermarking scheme is presented. Taking into account the property of the human visual system, the proposed scheme embeds the watermark into the wavelet coefficients representative of the images areas highly dense of details. More specifically a two stages unconventional wavelet decomposition is used. In fact, after having performed a 2D one-level wavelet decomposition, the high frequency wavelet subbands are further wavelet decomposed, thus obtaining those coefficients where the mark is finally embedded. Experimental results demonstrate that this embedding strategy allows to greatly increase the local ratio between the mark and the original image energies, thus leading to robustness even against severe image degradations, without transparency loss.

Wavelet-transform-based videoconferencing system with spatio-temporal scalability

In this paper, the design of a video conference system is outlined. The proposed scheme allows the various attendees to access the multipoint video distribution center via channels of different nature and capacity without resorting to parallel bank of coders or multiple decoding-coding conversions. This approach allows to obtain a scalability of the user profile which is not present in DCT based video codecs, where the distribution of the encoded video to different attendees is performed by using a unique bit rate adjusted according to the capacity of the worst connection. In this contribution a video coder based on spatio-temporal multiresolution pyramid generated by a 3D separable Wavelet transform is proposed. Experimental results show the capability of the proposed method.