Method and apparatus for entropy encoding blocks of transform coefficients of a video signal using a zigzag scan sequence, and method and apparatus for a corresponding decoding

摘要

A key in efficient image compression is to explore source correlation so as to find a compact representation of coded image data. For encoding DCT transformed and quantised pixel blocks, based on statistical properties of such DCT transform, the coefficient blocks are scanned in a known zigzag line sequence. According to the invention, when combining DCT with DWT by DCT transforming DWT coefficient blocks, the DCT coefficient blocks of the LH, HL and HH subbands of the DWT blocks are scanned using a different zigzag scan for each one of these subbands, followed by entropy encoding.