| 摘要 |
A method and an apparatus of image compression, and a memory to store a data structure for compression. The method includes, for an ordered series of quantized coefficients of a transform of an image block, forming events from the series of quantized transform coefficients, each event being a run of non-zero-valued coefficients in a first contiguous region defined by a breakpoint, a run of zero-valued coefficients in the first region, or a run of zero-valued coefficients in a second region defined by the breakpoint, the breakpoint defining the first region and a second continuous region in the series following the first region. The method further includes forming a codeword for each runlength of non-zero-valued coefficients in the first region, the forming a codeword according to a first coding method, forming a codeword for each runlength of zero-valued coefficients in the first region, the forming a codeword according to a second coding method, and encoding the coefficient values in the second region according to a third coding method, the third coding method including identifying runs of zero-valued coefficients in the second region. Relatively short codewords are formed to represent runlengths that are relatively more likely to occur, and relatively long codewords are formed to represent runlengths that are relatively less likely to occur.
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