Bit-depth scalability

摘要

To increase efficiency of a bit-depth scalable data-stream an inter-layer prediction is obtained by mapping samples of the representation of the picture or video source data with a first picture sample bit-depth from a first dynamic range corresponding to the first picture sample bit-depth to a second dynamic range greater than the first dynamic range and corresponding to a second picture sample bit-depth being higher than the first picture sample bit-depth by use of one or more global mapping functions being constant within the picture or video source data or varying at a first granularity, and a local mapping function locally modifying the one or more global mapping functions and varying at a second granularity smaller than the first granularity, with forming the quality-scalable data-stream based on the local mapping function such that the local mapping function is derivable from the quality-scalable data-stream.

主权项

1. Encoder for encoding a picture or video source data into a quality-scalable data stream, comprising a processor programmed to include, or circuit components arranged to include:
a base encoder arranged to encode the picture or video source data into a base encoding data stream representing a representation of the picture or video source data with a first picture sample bit depth; a mapper arranged to map samples of the representation of the picture or video source data with the first picture sample bit depth from a first dynamic range corresponding to the first picture sample bit depth to a second dynamic range greater than the first dynamic range and corresponding to a second picture sample bit depth being higher than the first picture sample bit depth, according to a combined mapping function, and to compute, for each of the samples, the combined mapping function by arithmetically combining a global mapping function that is constant within the picture or video source data or varies at a first granularity, and a local mapping function that varies at a second granularity finer than the first granularity at a respective position of each of the samples to acquire a prediction of the picture or video source data comprising the second picture sample bit depth; a residual encoder arranged to encode a prediction residual of the prediction into a bit-depth enhancement layer data stream; and a combiner arranged to output the quality-scalable data stream based on the base encoding data stream, the local mapping function, and the bit-depth enhancement layer data stream, so that the local mapping function is derivable from the quality-scalable data stream; wherein the combiner and the mapper are arranged such that the second granularity subdivides the picture or video source data into a plurality of picture blocks and the mapper is arranged such that the local mapping function is m·s+n with m and n varying at the second granularity with the combiner being arranged such that m and n are defined within the quality scalable data-stream for each picture block of the picture or video source data so that m and n may differ among the plurality of picture blocks.