Picture coding supporting block merging and skip mode

An apparatus for decoding a bitstream into which an image is encoded, the apparatus comprising:

• a subdivider configured to subdivide the image into a plurality of sample sets of samples;
• a merger configured to merge the plurality of sample sets into a plurality of groups each including one or more sample sets;
• a decoder configured to decode the image using coding parameters transmitted in the bitstream in units of the groups of the sample sets, wherein the decoder is configured to decode the image by predicting the image, decoding a prediction residual for a predetermined sample set and combining the prediction residual and a prediction resulting from predicting the image for the predetermined sample set;
• an extractor configured to extract the prediction residual and the coding parameters from the bitstream together with one or more syntax elements for each of at least a subset of a respective sample set, the one or more syntax elements indicating whether the respective sample set is to be merged into one of the plurality of groups together with another sample set or not, wherein the merger is configured to perform the merging in response to the one or more syntax elements,
• wherein the extractor and the merger are configured to:
• sequentially step through the sample sets according to a sample set scan order,
• for a current sample set, extract a first binary syntax element from the bitstream using arithmetically decoding using a first context,
• if the first binary syntax element is determined to be a first binary state, merge the current sample set into one group of the plurality of groups by inferring that coding parameters for the current sample set are equal to coding parameter associated with the group, skip extraction of the prediction residual for the current sample set, and step to a next sample set according to the sample set scan order,
• if the first binary syntax element is determined to be a second binary state, extract a second syntax element from the bitstream using arithmetically decoding using a second context different from the first context, and
• depending on the second syntax element,
• extract a third syntax element from the bitstream using arithmetically decoding using a third context different from the first context and the second context, merge the current sample set into one of the plurality of groups by inferring that coding parameters indicated by the third syntax element for the current sample set are equal to coding parameters associated with one of a set of predetermined candidate sample sets neighboring the respective sample set, and extract at least one further syntax element related to the prediction residual for the current sample set, or
• extract the coding parameters for the current sample set, and extract at least one further syntax element related to the prediction residual for the current sample set,
• wherein the prediction residual is represented by a transformation coefficient level.

An apparatus for encoding an image, the apparatus comprising:

• a subdivider configured to subdivide the image into a plurality of sample sets of samples;
• a merger configured to merge the plurality of sample sets into a plurality of groups each including one or more sample sets;
• an encoder configured to encode the image using coding parameters that vary across the image in units of the groups of the sample sets, wherein the encoder is configured to encode the image by predicting the image and encoding a prediction residual for a predetermined sample set;
• a bitstream generator configured to insert the prediction residual and the coding parameters into a bitstream together with one or more syntax elements for each of at least a subset of a respective sample set, the one or more syntax elements indicating whether the respective sample set is to be merged into one of the plurality of groups together with another sample set or not,
• wherein the bitstream generator is configured to:
• sequentially step through the sample sets according to a sample set scan order,
• for a current sample set, insert a first binary syntax element into the bitstream using arithmetically encoding using a first context,
• wherein if the first binary syntax element is determined to be a first binary state, the first binary syntax element indicates that the current sample set is merged into one group of the plurality of groups by inferring that coding parameters for the current sample set are equal to coding parameter associated with the group, and indicates skipping extraction of the prediction residual for the current sample set and stepping to a next sample set according to the sample set scan order,
• if the first binary syntax element is determined to be a second binary state, insert a second syntax element into the bitstream using arithmetically encoding using a second context different from the first context, and insert at least one further syntax element related to the prediction residual for the current sample set,
• wherein the second syntax element indicates whether to merge the current sample set into one of the plurality of groups or whether to perform extraction of the coding parameters for the current sample set,
• if the second syntax element indicates to merge the current sample set, insert a third syntax element into the bitstream and merge the current sample set by inferring that coding parameters indicated by the third syntax element for the current sample set are equal to coding parameters associated with one of a set of predetermined candidate sample sets neighboring the respective sample set, using arithmetically encoding using a third context different from the first context and the second context,
• wherein the prediction residual is represented by a transformation coefficient level.

A method for decoding a bitstream into which an image is encoded, the method comprising:

• subdividing the image into a plurality of sample sets of samples;
• merging the plurality of sample sets into a plurality of groups each including one or more sample sets;
• decoding the image using coding parameters transmitted in the bitstream in units of the groups of the sample sets, by predicting the image, decoding a prediction residual for a predetermined sample set and combining the prediction residual and a prediction resulting from predicting the image for the predetermined sample set;
• extracting the prediction residual and the coding parameters from the bitstream together with one or more syntax elements for each of at least a subset of a respective sample set, the one or more syntax elements indicating whether the respective sample set is to be merged into one of the plurality of groups together with another sample set or not, wherein the merging is performed in response to the one or more syntax elements;
• sequentially stepping through the sample sets according to a sample set scan order;
• for a current sample set, extracting a first binary syntax element from the bitstream using arithmetically decoding using a first context;
• if the first binary syntax element is determined to be a first binary state, merging the current sample set into one group of the plurality of groups by inferring that coding parameters for the current sample set are equal to coding parameter associated with the group, skipping extraction of the prediction residual for the current sample set, and stepping to a next sample set according to the sample set scan order;
• if the first binary syntax element is determined to be a second binary state, extracting a second syntax element from the bitstream using arithmetically decoding using a second context different from the first context;
• and
• depending on the second syntax element,
• extracting a third syntax element from the bitstream using arithmetically decoding using a third context different from the first context and the second context, merging the current sample set into one of the plurality of groups by inferring that coding parameters indicated by the third syntax element for the current sample set are equal to coding parameters associated with one of a set of predetermined candidate sample sets neighboring the respective sample set, and extracting at least one further syntax element related to the prediction residual for the current sample set, or
• extracting the coding parameters for the current sample set, and extracting at least one further syntax element related to the prediction residual for the current sample set, wherein the prediction residual is represented by a transformation coefficient level.

A method for encoding an image, the method comprising:

• subdividing the image into a plurality of sample sets of samples;
• merging the plurality of sample sets into a plurality of groups each including one or more sample sets;
• encoding the image using coding parameters that vary across the image in units of the groups of the sample sets, by predicting the image and encoding a prediction residual for a predetermined sample set;
• inserting the prediction residual and the coding parameters into a bitstream together with one or more syntax elements for each of at least a subset of a respective sample set, the one or more syntax elements indicating whether the respective sample set is to be merged into one of the plurality of groups together with another sample set or not;
• sequentially stepping through the sample sets according to a sample set scan order;
• for a current sample set, inserting a first binary syntax element into the bitstream using arithmetically encoding using a first context;
• wherein if the first binary syntax element is determined to be a first binary state, the first binary syntax element indicates that the current sample set is merged into one group of the plurality of groups by inferring that coding parameters for the current sample set are equal to coding parameter associated with the group, and indicates skipping extraction of the prediction residual for the current sample set and stepping to a next sample set according to the sample set scan order;
• if the first binary syntax element is determined to be a second binary state, inserting a second syntax element into the bitstream using arithmetically encoding using a second context different from the first context, and inserting at least one further syntax element related to the prediction residual for the current sample set;
• wherein the second syntax element indicates whether to merge the current sample set into one of the plurality of groups or whether to perform extraction of the coding parameters for the current sample set;
• and
• if the second syntax element indicates to merge the current sample set, inserting a third syntax element into the bitstream and merging the current sample set by inferring that coding parameters indicated by the third syntax element for the current sample set are equal to coding parameters associated with one of a set of predetermined candidate sample sets neighboring the respective sample set, using arithmetically encoding using a third context different from the first context and the second context,
• wherein the prediction residual is represented by a transformation coefficient level.

An apparatus configured to decode a bitstream into which an image is encoded, a sample array of the image being partitioned into a plurality of blocks, and the bitstream indicating whether each respective block of the plurality of blocks is encoded in intra-picture prediction mode or inter-picture prediction mode, the apparatus being configured to:

• extract a flag from the bitstream for a current block;
• use the flag to determine:
• whether coding parameters associated with the current block are to be set by merging based on a merge candidate or to be retrieved from the bitstream,
• whether the current block is to be reconstructed merely based on a prediction signal depending on the coding parameters associated with the current block without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current block based on residual data within the bitstream, and
• whether the current block is encoded in inter-picture prediction mode;
• if the flag within the bitstream indicates that the coding parameters associated with the current block are to be set based on a merge candidate, that the residual data of the current block is not transmitted, and that the current block is encoded in the inter-picture prediction mode,
• perform the merging such that the coding parameters associated with the current block are obtained by setting the coding parameters based on a merge candidate, and
• reconstruct the current block using the inter-picture prediction mode merely based on a prediction signal depending on the coding parameters without any residual data;
• and
• if the flag within the bitstream indicates that the coding parameters associated with the current block are not to be set based on a merge candidate,
• extract, from the bitstream, a syntax element indicating whether the current block is encoded in intra-picture prediction mode or inter-picture prediction mode, and if the syntax element indicates that the current block is encoded in inter-picture prediction mode, the current block is further partitioned for each partition of the current block, and a merge flag indicates an individual merge of respective partitions,
• wherein the residual data is represented by a transformation coefficient level.

An apparatus for decoding a bitstream into which an image is encoded, the apparatus comprising:

• a subdivider configured to subdivide the image into a plurality of blocks of samples;
• a merger configured to merge the plurality of blocks into a plurality of groups each including one or more blocks;
• a decoder configured to decode the image using coding parameters transmitted in the bitstream in units of the groups of the blocks, wherein the decoder is configured to decode the image by predicting the image, decoding a prediction residual for a predetermined block and combining the prediction residual and a prediction resulting from predicting the image for the predetermined block, wherein, for each respective block, the bitstream indicates whether the respective block is encoded in intra-picture prediction mode or inter-picture prediction mode;
• an extractor configured to extract the prediction residual and the coding parameters from the bitstream together with one or more syntax elements for each of at least a subset of a respective block, the one or more syntax elements indicating:
• whether the respective block is encoded in inter-picture prediction mode, whether the respective block is to be merged into one of the plurality of groups together with another block, and whether residual data of the respective block is to be transmitted, wherein the merger is configured to perform the merging in response to the one or more syntax elements,
• wherein one of possible states of the one or more syntax elements indicates that the respective block is encoded in inter-picture prediction mode, that the respective block is to be merged into one of the plurality of groups together with another block, and that the respective block has no prediction residual encoded and inserted into the bitstream,
• wherein the extractor is configured to extract, for each block for which the one or more syntax elements is not determined to be one of the possible states, a syntax element from the bitstream indicating whether the respective block is encoded in intra-picture prediction mode or inter-picture prediction mode, wherein a partitioning information indicates a partitioning of the respective block and, if the respective block is encoded in inter-picture prediction mode, for each partition into which the respective block is partitioned according to the partitioning information, a merge flag indicates an individual merge of respective partitions,
• wherein the prediction residual is represented by a transformation coefficient level.

A method for decoding a bitstream into which an image is encoded,

• subdividing the image into a plurality of blocks of samples;
• merging the plurality of blocks into a plurality of groups each including one or more blocks;
• decoding the image using coding parameters transmitted in the bitstream in units of the groups of the blocks, by predicting the image, decoding a prediction residual for a predetermined block and combining the prediction residual and a prediction resulting from predicting the image for the predetermined block, wherein, for each respective block, the bitstream indicates whether the respective block is encoded in intra-picture prediction mode or inter-picture prediction mode;
• extracting the prediction residual and the coding parameters from the bitstream together with one or more syntax elements for each of at least a subset of a respective block, the one or more syntax elements indicating:
• whether the respective block is encoded in inter-picture prediction mode, whether the respective block is to be merged into one of the plurality of groups together with another block, and whether residual data of the respective block is to be transmitted, wherein the merging is performed in response to the one or more syntax elements,
• wherein one of possible states of the one or more syntax elements indicates that the respective block is encoded in inter-picture prediction mode, that the respective block is to be merged into one of the plurality of groups together with another block, and that the respective block has no prediction residual encoded and inserted into the bitstream,
• wherein the extracting comprises extracting, for each block for which the one or more syntax elements is not determined to be one of the possible states, a syntax element from the bitstream indicating whether the respective block is encoded in intra-picture prediction mode or inter-picture prediction mode, wherein a partitioning information indicates a partitioning of the respective block and, if the respective block is encoded in inter-picture prediction mode, for each partition into which the respective block is partitioned according to the partitioning information, a merge flag indicates an individual merge of respective partitions,
• wherein the prediction residual is represented by a transformation coefficient level.