Abstract
In this thesis, we present an optimal chain-code-like representation to code contour shapes; in addition, this representation can be easily extended to as a scalable form which structures shape data as the base layer followed by two enhancement layers. Lossy coding scheme is also presented for low-bit-rate applications. Two schemes are further presented to achieve scalable coding with two downsized strategies. In the first one, the down-sampling scheme, the scalability can be recognized in both spatial and quality-wise. Another one, called the contour approximation scheme, the tradeoff between encoding cost and resulting distortion is considered. We conducted several experiments for the lossless, lossy and scalable methods. Comparing to the block-based CAE method in MPEG-4 and DCC with arithmetic coder, our lossless method not only has the higher compression ratio with less computation steps, but also can be applied to layered transmission. Comparing to the novel scalable shape coding one, the progressive polygon encoding method, in case of the base layer with distortion Dn = 0.02, our scheme saves about 20~30% amount of bits. That is, we have a smaller size base layer, which is important in layered transmission.