Inter-component prediction
Reconstructing a second component signal relating to a second component of a multi-component picture from a spatially corresponding portion of a reconstructed first component signal and a correction signal derived from data stream for the second component promises increased coding efficiency over a broader range of multi-component picture content. By including the spatially corresponding portion of the reconstructed first component signal into the reconstruction of the second component signal, any remaining inter-component redundancies/correlations present such as still present despite a possibly a priori performed component space transformation, or present because of having been introduced by such a priori performed component space information, for example, may readily be removed by way of the inter-component redundancy/correlation reduction of the second component signal.
1 . A decoder configured to decode a multi-component picture, the decoder comprising a processor configured for:
determining, based on information extracted from an encoded data stream, a first residual signal relating to a first component of the multi-component picture;
extracting, from the encoded data stream, a first signaling syntax element that indicates whether or not an inter-component prediction is enabled for the multicomponent picture;
extracting, from the encoded data stream, a second signaling syntax element that indicates a scaling factor based on which the first residual signal is to be added to a second residual signal of a second component of the multi-component picture to generate a new residual signal for replacing the second residual signal;
extracting, from the encoded data stream, a third signaling syntax element associated with the second signaling syntax element;
deriving a portion of the second residual signal based on a portion of the first residual signal scaled using the scaling factor and the third signaling syntax element; and
reconstructing the multi-component picture based on the first residual signal and the second residual signal.
2 . The decoder according to claim 1 , wherein the scaling factor is decoded based on truncated unary binarization and context-adaptive binary arithmetic coding.
3 . The decoder according to claim 1 , wherein the third signaling syntax element indicates a sign value of the scaling factor when the scaling factor is not equal to zero.
4 . The decoder according to claim 3 , wherein the sign value is decoded based on context-adaptive binary arithmetic coding.
5 . The decoder according to claim 1 , wherein the portion of the second residual signal is derived based on scaling the portion of the first residual signal using the scaling factor, a bit depth value of the first component, and a bit depth value of the second component.
6 . The decoder according to claim 1 , wherein the processor is further configured for:
extracting, from the encoded data stream, a fourth signaling syntax element that indicates a second scaling factor based on which the first residual signal is to be added to a third residual signal of a third component of the multi-component picture to generate a new residual signal for replacing the third residual signal;
extracting, from the encoded data stream, a fifth signaling syntax element associated with the fourth signaling syntax element;
deriving a portion of the third residual signal based on a portion of the first residual signal scaled using the second scaling factor and the fifth signaling syntax element; and
reconstructing the multi-component picture based on the first residual signal, the second residual signal and the third residual signal.
7 . The decoder according to claim 6 , wherein the first, second and third components are three color components of the multi-component picture.
8 . The decoder according to claim 1 , wherein the processor is configured for:
sub-dividing the multi-component picture into prediction blocks and residual blocks;
sub-dividing the residual blocks into transform blocks;
selecting prediction modes based on first information from the encoded data stream;
determining prediction parameters for the prediction blocks based on second information from the encoded data stream;
deriving a prediction signal using the prediction modes and the prediction parameters;
deriving a residual signal within each residual block by performing inverse transformations within the transform blocks; and
reconstructing the multi-component picture by combining the prediction signal and the residual signal.
9 . A method for decoding a multi-component picture, comprising:
determining, based on information extracted from an encoded data stream, a first residual signal relating to a first component of the multi-component picture;
extracting, from the encoded data stream, a first signaling syntax element that indicates whether or not an inter-component prediction is enabled for the multicomponent picture;
extracting, from the encoded data stream, a second signaling syntax element that indicates a scaling factor based on which the first residual signal is to be added to a second residual signal of a second component of the multi-component picture to generate a new residual signal for replacing the second residual signal;
extracting, from the encoded data stream, a third signaling syntax element associated with the second signaling syntax element;
deriving a portion of the second residual signal based on a portion of the first residual signal scaled using the scaling factor and the third signaling syntax element; and
reconstructing the multi-component picture based on the first residual signal and the second residual signal.
10 . The method according to claim 9 , wherein:
the scaling factor is decoded based on truncated unary binarization and context-adaptive binary arithmetic coding.
11 . The method according to claim 9 , wherein:
the third signaling syntax element indicates a sign value of the scaling factor when the scaling factor is not equal to zero.
12 . The method according to claim 11 , wherein:
the sign value is decoded based on context-adaptive binary arithmetic coding.
13 . The method according to claim 9 , wherein the portion of the second residual signal is derived based on scaling the portion of the first residual signal using the scaling factor, a bit depth value of the first component, and a bit depth value of the second component.
14 . The method according to claim 9 , further comprising:
extracting, from the encoded data stream, a fourth signaling syntax element that indicates a second scaling factor based on which the first residual signal is to be added to a third residual signal of a third component of the multi-component picture to generate a new residual signal for replacing the third residual signal;
extracting, from the encoded data stream, a fifth signaling syntax element associated with the fourth signaling syntax element;
deriving a portion of the third residual signal based on a portion of the first residual signal scaled using the second scaling factor and the fifth signaling syntax element; and
reconstructing the multi-component picture based on the first residual signal, the second residual signal and the third residual signal.
15 . The method according to claim 14 , wherein the first, second and third components are three color components of the multi-component picture.
16 . The method according to claim 9 , further comprising:
sub-dividing the multi-component picture into prediction blocks and residual blocks;
sub-dividing the residual blocks into transform blocks;
selecting prediction modes based on first information from the encoded data stream;
determining prediction parameters for the prediction blocks based on second information from the encoded data stream;
deriving a prediction signal using the prediction modes and the prediction parameters;
deriving a residual signal within each residual block by performing inverse transformations within the transform blocks; and
reconstructing the multi-component picture by combining the prediction signal and the residual signal.
17 . A method for encoding a multi-component picture, comprising:
obtaining a first residual signal relating to a first component of the multicomponent picture;
encoding, into a data stream, the first residual signal;
encoding, into the data stream, a first signaling syntax element that indicates whether or not an inter-component prediction is enabled for the multi-component picture;
encoding, into the data stream, a second signaling syntax element that indicates a scaling factor based on which the first residual signal is to be added to a second residual signal of a second component of the multi-component picture to generate a new residual signal for replacing the second residual signal; and
encoding, into the data stream, a third signaling syntax element associated with the second signaling syntax element, wherein a portion of the second residual signal is derived based on a portion of the first residual signal scaled using the scaling factor and the third signaling syntax element.
18 . The method according to claim 17 , wherein:
the scaling factor is encoded based on truncated unary binarization and context-adaptive binary arithmetic coding.
19 . The method according to claim 17 , wherein:
the third signaling syntax element indicates a sign value of the scaling factor when the scaling factor is not equal to zero.
20 . The method according to claim 19 , wherein:
the sign value is encoded based on context-adaptive binary arithmetic coding.