Selective inter-component transform (ICT) for image and video coding
AssigneeFraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
InventorsChristian Helmrich, Christian Rudat, Tung Hoang Nguyen, Heiko Schwarz, Detlev Marpe, Thomas Wiegand
Life of this patent
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Abstract
An encoder for encoding a plurality of components of an image content region of an image to be encoded is configured for obtaining the plurality of components representing the image content region; selecting an intercomponent transform from a set of intercomponent transforms; encoding the plurality of components using the selected intercomponent transform to obtain encoded components; and providing the encoded components.
Claims14
A block based video encoder comprising at least one processor for jointly coding residual samples of a first chroma block, Cb, and a second chroma block, Cr, the first and second chroma blocks being different color components of a corresponding picture block, the at least one processor configured to:
- select a pair of coefficients (a, b) from a plurality of pairs of coefficients;
- determine a jointly coded block, C, from the first chroma block and the second chroma block, wherein a reconstructed jointly coded block, C′, is obtained from an encoded jointly coded block, and a reconstructed first chroma block, Cb′, and a reconstructed second chroma block, Cr′ are determined according to
- Cb
- ′
- =
- aC
- ′
-
- and
-
- Cr
- ′
- =
- bC
- ′
- ;
- encode the jointly coded block;
- and
- signal to a decoder the selected pair of coefficients (a, b) from the plurality of pairs of coefficients using a coded block flag (CBF) of the reconstructed first chroma block, which if set indicates that at least one residual sample of the reconstructed first chroma block is nonzero, and a CBF of the reconstructed second chroma block, which if set indicates that at least one residual sample of the reconstructed second chroma block is nonzero.
A block based video decoder comprising at least one processor configured for decoding jointly coded residual samples of a first chroma block and a second chroma block from a bitstream, the first and second chroma blocks being different chroma color components of a corresponding picture block, for the at least one processor configured to:
- decode, from the bitstream, a binary flag which indicates that the first chroma block and the second chroma block are jointly coded;
- determine a reconstructed jointly coded block, C′, from the bitstream;
- decode, from the bitstream, a coded block flag (CBF) of a reconstructed first chroma block, Cb′, which if set indicates that at least one residual sample of the reconstructed first chroma block is nonzero, and a CBF of a reconstructed second chroma block, Cr′, which if set indicates that at least one residual sample of the reconstructed second chroma block is nonzero;
- determine a pair of coefficients (a, b) of a plurality of pairs of coefficients based on the CBF of the reconstructed first chroma block and the CBF of the reconstructed second chroma block;
- and
- determine the reconstructed first chroma block, Cb′, and the reconstructed second chroma block, Cr′, according to
- Cb
- ′
- =
- aC
- ′
-
- and
-
- Cr
- ′
- =
- bC
- ′
- .
A method of block based video decoding for decoding jointly coded residual samples of a first chroma block and a second chroma block from a bitsream, the first and second chroma blocks being different color components of a corresponding picture block, the method comprising:
- decoding, from the bitstream, a binary flag which indicates that the first chroma block and the second chroma block are jointly coded;
- determining a reconstructed jointly coded block, C′, from the bitstream;
- decoding, from the bitstream, a coded block flag (CBF) of a reconstructed first chroma block, Cb′, which if set indicates that at least one residual sample of the reconstructed first chroma block is nonzero, and a CBF of a reconstructed second chroma block, Cr′, which if set indicates that at least one residual sample of the reconstructed second chroma block is nonzero;
- determining a pair of coefficients (a, b) of a plurality of pairs of coefficients based on the CBF of the reconstructed first chroma block and the CBF of the reconstructed second chroma block;
- and
- determining a reconstructed first chroma block, Ch′, and a reconstructed second chroma block, Cr′, according to Cb′=a C′ and Cr′=b C′.
Dependencies are inferred from the claim text.