Quad-Tree Block-Based Binary Shape Coding

Shape masks are used in object-based video coding, such as MPEG-4 part 2, to specify the boundaries of a video object. The term ldquobinary shaperdquo is used to describe shape masks where each pixel is either completely inside the object or completely outside it, i.e., there is no blending of pixels at object boundaries. In this paper, we present a new lossless block-based coding algorithm for binary shapes that combines a quad-tree structure with context-based arithmetic coding. Experimental results demonstrate that this new approach provides a saving in bits generated up to approximately 66% compared to the MPEG-4 binary shape coding algorithm.