Bit-depth scalability

Abstract

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.

1 . (canceled) 
     
     
         2 . Method for decoding a quality-scalable data stream into which picture or video source data is encoded, the quality-scalable data stream comprising a base layer data stream representing the picture or video source data with a first picture sample bit depth and a first spatial resolution, an enhancement layer data stream representing a prediction residual with a second picture sample bit depth being higher than the first picture sample bit depth and a second spatial resolution higher than the first spatial resolution, and a local mapping function defined at a second granularity, the method comprising:
 decoding the base layer data stream into a lower bit-depth reconstructed picture or video data;   decoding the enhancement data stream into the prediction residual;   spatially interpolate, using a spatial interpolation filter, samples of the lower bit-depth reconstructed picture or video data so as to increase the first spatial resolution to correspond with the second spatial resolution;   mapping samples of the lower bit-depth reconstructed picture or video 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 the second picture sample bit depth, by use of one or more global mapping functions being constant within the video or varying at a first granularity, and a local mapping function locally modifying the one or more global mapping functions at the second granularity being smaller than the first granularity, to acquire a prediction of the picture or video source data comprising the second picture sample bit depth; and   reconstructing the picture with the second picture sample bit depth based on the prediction and the prediction residual.   
     
     
         3 . Method according to  claim 2 , wherein an order in which the spatial interpolation and mapping is performed, is adaptively chosen on a block-by-block basis. 
     
     
         4 . Method according to  claim 2 , wherein an order in which the spatial interpolation and mapping is performed, is adaptively chosen on a picture-by-picture basis. 
     
     
         5 . Method according to  claim 2 , wherein an order in which the spatial interpolation and mapping is performed, is adaptively chosen at a granularity which is signaled in the quality-scalable data stream. 
     
     
         6 . Method according to  claim 2 , wherein an order in which the spatial interpolation and mapping is performed, is signaled as side information in the quality-scalable data stream. 
     
     
         7 . Decoder for decoding a quality-scalable data stream into which picture or video source data is encoded, the quality-scalable data stream comprising a base layer data stream representing the picture or video source data with a first picture sample bit depth and a first spatial resolution, an enhancement layer data stream representing a prediction residual with a second picture sample bit depth being higher than the first picture sample bit depth and a second spatial resolution higher than the first spatial resolution, and a local mapping function defined at a second granularity, the decoder comprising:
 decoder for decoding the base layer data stream into a lower bit-depth reconstructed picture or video data;   decoder for decoding the enhancement data stream into the prediction residual;   interpolator for spatially interpolating, using a spatial interpolation filter, samples of the lower bit-depth reconstructed picture or video data so as to increase the first spatial resolution to correspond with the second spatial resolution and mapping samples of the lower bit-depth reconstructed picture or video 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 the second picture sample bit depth, by use of one or more global mapping functions being constant within the video or varying at a first granularity, and a local mapping function locally modifying the one or more global mapping functions at the second granularity being smaller than the first granularity, to acquire a prediction of the picture or video source data comprising the second picture sample bit depth; and   reconstructor for reconstructing the picture with the second picture sample bit depth based on the prediction and the prediction residual.   
     
     
         8 . Decoder according to  claim 7 , wherein an order in which the spatial interpolation and mapping is performed, is adaptively chosen on a block-by-block basis. 
     
     
         9 . Decoder according to  claim 7 , wherein an order in which the spatial interpolation and mapping is performed, is adaptively chosen on a picture-by-picture basis. 
     
     
         10 . Decoder according to  claim 7 , wherein an order in which the spatial interpolation and mapping is performed, is adaptively chosen at a granularity which is signaled in the quality-scalable data stream. 
     
     
         11 . Decoder according to  claim 7 , wherein an order in which the spatial interpolation and mapping is performed, is signaled as side information in the quality-scalable data stream. 
     
     
         12 . Method according to  claim 2 , wherein an order in which the spatial interpolation and mapping is to be performed, is signaled as side information in the quality-scalable data stream. 
     
     
         13 . Method for encoding a picture or video source data into a quality-scalable data stream, comprising:
 encoding 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 and a first spatial resolution;   spatially interpolating, using a spatial interpolation filter, samples of the lower bit-depth reconstructed picture or video data so as to increase the first spatial resolution to correspond with a second spatial resolution higher than the first spatial resolution; and   mapping 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, 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 at a second granularity finer than the first granularity to acquire a prediction of the picture or video source data comprising the second picture sample bit depth;   encoding a prediction residual of the prediction into a bit-depth enhancement layer data stream; and   forming 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.   
     
     
         14 . Encoder for encoding a picture or video source data into a quality-scalable data stream, comprising:
 base encoder for encoding 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 and a first spatial resolution;   mapper for spatially interpolating, using a spatial interpolation filter, samples of the lower bit-depth reconstructed picture or video data so as to increase the first spatial resolution to correspond with a second spatial resolution higher than the first spatial resolution and mapping 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, 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 at a second granularity finer than the first granularity to acquire a prediction of the picture or video source data comprising the second picture sample bit depth;   residual encoder for encoding a prediction residual of the prediction into a bit-depth enhancement layer data stream; and   combiner for forming 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.   
     
     
         15 . A non-transitory computer-readable medium including a program code for performing, when running on a computer, the method according to  claim 2 . 
     
     
         16 . A non-transitory computer-readable medium including a program code for performing, when running on a computer, the method according to  claim 13 .