| 摘要 |
In a transmitter for image signals, a variable-length coder whose code set has been optimized for the order statistics of a run-length-coded bilevel image is used to code a stream of differential-pulse-code-modulated (DPCM) errors representing a multi-level image. The DPCM errors are first rearranged on a line-by-line basis in such a way that the rearranged error stream contains many long runs. Individual words in the rearranged error stream are then changed in such a way that, for at least one value of n, the n most-frequently-occurring words in the resulting, processed signal substantially have the aforementioned order statistics. The resulting signal is then run-length-coded, applied to the variable-length coder, and then transmitted. The reverse processing is performed at the receiver.
|
