No abstract

A new method for the lossy compression of segmentation maps is presented. In the first stage of the proposed algorithm, region boundary segments are coded, providing a coarse polygonal approximation of regions, as well as a complete representation of their adjacency. The second stage consists of the progressive refinement of these segments, until either the desired degree of accuracy is reached, or the target bit-rate is achieved. Rate-distortion curves demonstrate good lossy performance in the range of 0.3 to 0.6 bits per contour point.

A new approach to Variable Size Block Matching is proposed, based on the binary partitioning of blocks. If a particular block does not allow for accurate motion compensation, then it is split into two using the horizontal or vertical line that achieves the maximum reduction in motion compensation error. This method causes partitioning to occur along motion boundaries, thus substantially reducing blocking artifacts. In addition, small blocks are placed in regions of complex motion, while large blocks cover regions of uniform motion. The proposed technique provides significant gains in picture quality of 1.5 to 3.0 dB, when compared to Fixed Size Block Matching at the same total rate.

A content-based approach to the design of a triangular mesh is presented, and its application to affine motion compensation is investigated. An image is first segmented into moving objects, which are then approximated with polygons. Following this, a triangular mesh is generated within each polygon, thus ensuring that no triangle straddles multiple regions. Translation and affine motion parameters are determined for each triangle, using bi-directional motion estimation. Results for three test sequences demonstrate the advantages offered by the proposed mesh design method, and by the use of affine motion compensation.