The robustness against geometrical attacks remains one of the most challenging issues in watermarking of images and video. This Paper presents several improvements of the video watermarking approach presented in [1], namely (i) using a temporally low-pass watermark and (ii) synchronization to resist attacks along the temporal axis. In order to improve the watermark detection performance. we propose: to rose to use an amplitude. limiting filter and a whitening filter during the watermark extraction process. Experimental results show that the proposed techniques achieve good performanee.

In Fractal image coding (FIC), a parti-tioning of the original im age into ranges and domains is required, which greatly afects the coding performance. Usually, the more adaptive to the image content the partition is, the higher performance it can achieve. Nowadays, some alleged Region-based fractal coders (RBFC) using split-and-merge strategy can achieve better adaptivity and perform ance com pared with traditional rectangular block partitions. However, the regions are still with linear con. tour. In this paper, we present a Freely-shaped Region-based fractal coder rFs. (RBFC) using a two-step partitioning, i. e. coarse partitioning bas ed on fractal dim ension and fine partitioning based on region growth, which brings freely-shaped regions. Our highly im age-adaptive scheme can achieve better rate. distortion curve than conventional scheme, even more visually pleasing resultsat the same perform ance.

Multiple description (MD) coding has many applications in transmission of images over unreliable packet or multiple path networks that can not guarantee lossless data delivery. In this paper, an effective multiple description image coding scheme is introduced. This scheme is mainly based on the wavelet transform and multiple description lattice vector quantization (MDLVQ). The haracteristics of wavelet coefficients in different frequency subbands are taken into account in the design of the MD image coder with different optimized MDLVQ parameters. The experimental results are presented to demonstrate the effectiveness of the proposed scheme.

Abstract. In conventional fractal image coding (FIC) schemes, domain blocks are constrained to be twice as large as range blocks to ensure the convergence of their iterative decoding stage. However, this constraint has limited the fractal encoder to exploit the self-similarity at the same resolution scale of natural images. To overcome the shortcoming, a novel scheme using same-sized range and domain blocks is proposed. Further, a recursive scheme feeding the coding results back to the input during the encoding procedure is used to improve the decoded image quality. Experimental results show our method gives significant improvement over Fisher's FIC.

A new image data compression method using fractals and the discrete cosine transforms (DCT) is presented. The original image is first encoded by fractals in the DCT domain, then the error image is encoded using the DCT. Experiments show that the method can achieve high fidelity at a high compression ratio.