A novel intraframe source-coding algorithm suitable for the recording of digital high-definition television signals is presented. A multilayered, hierarchical description of the source signal is obtained by means of a quad-tree, halfband wavelet transform. This transform decomposes the input signal into a collection of spectrally nonoverlapping sub-bands. These are used to influence the allocation of the available coding resources to the various layers, so that the integrity of visually significant features can be preserved. Individual sub-bands are quantised and entropy coded by using a predictive arithmetic coding technique. The algorithm is tuned to achieve bit-rate reduction ratios in the range 8:1-4:1 which is most useful for recording applications. Results obtained from simulating the coding algorithm show noticeable improvement over the current state-of-the-art international standard algorithm for still picture encoding, both in terms of subjective quality and of measured mean-square error.
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