Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.

Santiago De Luxán Hernández

Thomas Wiegand

Detlev Marpe

Heiko Schwarz

Benjamin Bross

Philipp Merkle

Valeri George

Gayathri Venugopal

Phan Hoang Tung Nguyen

Jens Brandenburg

Klaus-Robert Mueller

Karsten Müller

Klaus-Robert Müller

Block-based coding of a picture is rendered more effective by providing an intra-prediction coding concept according to which a certain block of the picture is intra-prediction coded using a certain intra-coding mode by partitioning the predetermined block into partitions along a certain dimension with the number of partitions being greater than two and/or the partitions being one sample wide along the certain dimension with the partitions being, for reconstruction purposes, sequentially subject to spatial prediction using the intra-prediction coding mode signaled for the certain block followed by correcting the thus obtained predictor using a prediction residual so that for preceding partitions a reconstruction of the samples is available to the decoder at the time of processing the next, then current, partition. Signaling overhead with respect to the partitioning may be left off or may be kept low.

Partition-based intra-coding concept

Block-based coding of a picture is done by providing an intra-prediction coding concept according to which a certain block of the picture is intra-prediction coded using a certain intra-coding mode by partitioning the predetermined block into partitions which are, for reconstruction purposes, sequentially subject to spatial prediction using the intra-prediction coding mode signaled for the certain block followed by correcting the thus obtained predictor using a prediction residual so that for preceding partitions a reconstruction of the samples is available to the decoder at the time of processing the next, then current, partition.

Partitioned intra coding concept

The coding efficiency of predictive picture codecs using transform-based residual coding is enhanced by allowing the codec to switch between a set of transforms for the sake of the transform-based residual coding. It turned out that even when using explicit signaling from encoder to decoder in order to signal the actual transform to be used out of the set of transforms from encoder to decoder, an increase in coding efficiency may result. Alternatively, the switching between the set of transforms may be performed without explicit signaling at all, or using a combination of explicit signaling and some sort of prediction of the switching.

Image data compression using switching between a set of transforms

Decoder for decoding a picture, wherein blocks into which the picture is subdivided are assigned to a set of prediction types, which include intra prediction and inter prediction. For each of predetermined intra-predicted blocks, the decoder is configured to derive, from the data stream, an information on a partitioning of the respective predetermined intra-predicted block into partitions. The decoder is configured to derive, from the data stream, for each partition of the respective predetermined intra-predicted block, a partition-specific prediction residual signal related to a spatial domain prediction residual signal of the respective partition of the respective predetermined intra-predicted block via a predetermined transform. The predetermined transform can be identified out of a set of transforms including a first transform and a second transform, which equals a concatenation of a primary transform and a secondary transform applied onto a subset of coefficients of the primary transform.

Decoder, encoder and methods comprising a coding for intra subpartitions

In an encoder and a decoder for Region Based Intra Block Copy, the encoder may be configured for block-based encoding a picture into a data stream, and the decoder may be configured for block-based decoding a picture from a data stream. The encoder and decoder may further be configured to determine for a current block of the picture a difference between a first predetermined block and a second predetermined block inside a block search area. The encoder may encode the difference into the data stream and the decoder may derive the difference from the data stream. According to the innovative principle, the encoder and the decoder may be configured to partition the block search area into multiple block search regions.

Region based intra block copy

Decoder for decoding a transformed representation of a sample block from a data stream. If a first coded coefficient is located inside a predetermined subarea of the transform coefficient block and if the underlying transform is within a first set of available transforms, the decoder decodes coefficients along a first coefficient scan order. If the transform is within a second set of In available transforms, the decoder decodes coefficients located within the predetermined subarea along a second coefficient scan order, and infers that coefficients located outside the predetermined subarea are zero. The first coefficient scan order is so that coefficients outside the predetermined subarea are scanned between two transform coefficients located inside the predetermined subarea. The second coefficient scan order does not scan any coefficient outside the predetermined subarea between scanning the coefficients within the predetermined subarea.

Coding concepts for a transformed representation of a sample block

Decoder for block-based decoding of a picture from a data stream, configured to decode an intra-coding mode for a predetermined block of the picture from the data stream, configured to decode a partition dimension flag for the predetermined block of the picture from the data stream and set a partition dimension depending on the partition dimension flag to be horizontal or vertical and the decoder is configured to partition, along the predetermined dimension, the predetermined block into transform partitions which are as wide as the predetermined block perpendicular to predetermined dimension, furthermore configured to decode, for each transform partition, a transform of a prediction residual from the data stream; intra-predicting the predetermined block depending on one or more already reconstructed samples neighboring the predetermined block in a manner depending on the intra-coding mode to obtain a predictor for the predetermined block; and reconstructing the predetermined block by correcting the predictor within each transform partition using the transform of the prediction residual decoded for the respective transform partition.

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Berlin, Germany

Santiago De Luxán Hernández