A Doubly Error Resilient Coder of Image Sequences

Many scenarios require single frame random access and error resilience in coding, transmission, and decoding of image sequences. We propose in this paper a SPIHT coder that encodes a sequence of images one frame at a time and uses two methods together to achieve strong error resilience. The first method groups wavelet coefficients into a number of tree blocks and the second one encodes these tree blocks independently using SPIHT with progressive significance maps. Because a substantial part of a progressive significance map contains a fixed-length code stream called the complementary significance map (comp-sigmap), transmission bit errors do not propagate within the compsig-map. Furthermore, since the block trees are encoded independently, no error in a given bitstream propagates to another bitstream. Simulations show that the two methods together show stronger error resilience than either one separately. Furthermore, because the groups are formed by interleaved spatial orientation trees, faulty reconstruction from bit errors affecting a given treeblock can be concealed by estimating the true wavelet coefficients from neighboring coefficients in adjacent error-free spatial orien-