Abstract: An encoding method for a picture part encoded in a bitstream and reconstructed can involve refinement data encoded in the bitstream and determined based on at least one comparison of a version of a rate distortion cost computed using a data coding cost, a distortion between an original version of the picture part and a reconstructed picture part, and at least one other version involving one or more combinations of with or without a refinement by the refinement data, or a refinement either in or out of the decoding loop, or with or without a mapping or an inverse mapping.

Abstract: Apparatuses and methods for encoding or decoding picture information that involve determining a scaling factor to scale a chroma prediction residual associated with chroma information included in the picture information; scaling the chroma prediction residual based on the scaling factor to provide a scaled chroma prediction residual; and encoding or decoding at least a portion of the picture information based on the scaled chroma prediction residual.

Abstract: Encoding or decoding picture information can involve determining a first scaling factor varying with a first granularity to scale a chroma prediction residual associated with chroma information included in the picture information; determining a second scaling factor varying with a second granularity finer than the first granularity; scaling the chroma prediction residual based on a combination of the first scaling factor and the second scaling factor to provide a scaled chroma prediction residual with the second granularity; and encoding or decoding at least a portion of the picture information based on the scaled chroma prediction residual.

Abstract: A method for decoding a picture block is disclosed. The decoding method comprises:—decoding (10) at least one stream S_diff into decoded data and into one information for identifying a re-constructed reference picture in a decoder picture buffer;—reconstructing (12) a special reference picture from at least the identified reconstructed reference picture and from the decoded data;—reconstructing (16) the picture block from at least the special reference picture, wherein the at least the special reference picture is not displayed.

Abstract: A method for decoding a picture block is disclosed. The decoding method comprises: —decoding (10) at least one stream S_diff into decoded data and into one information for identifying a reconstructed reference picture in a decoder picture buffer; —reconstructing (12) a special reference picture from at least the identified reconstructed reference picture and from the decoded data; —reconstructing (16) the picture block from at least the special reference picture, wherein the at least the special reference picture is not displayed.

Abstract: Described are systems and methods for encoding or decoding a picture part of video information can include using a refinement mode per block where the refinement mode can be based on a refinement parameter. The refinement mode can include a cross-component refinement that can be a cross-component chroma refinement. The refinement mode can include enabling selection per block of a refinement parameter where the refinement parameter can include one or more chroma refinement parameters included in a chroma refinement table.

Abstract: A method for decoding a picture block is disclosed. The decoding method comprises: —decoding (10) at least one stream S_diff into decoded data and into one information for identifying a reconstructed reference picture in a decoder picture buffer; —reconstructing (12) a special reference picture from at least the identified reconstructed reference picture and from the decoded data; —reconstructing (16) the picture block from at least the special reference picture, wherein the at least the special reference picture is not displayed.

Abstract: Reshaping can be used to better exploit the sample value distribution of video data. When reshaping is used inside the coding loop, forward mapping is applied to prediction signals from intra or inter prediction, and inverse mapping is applied to reconstructed signals. To simplify the inverse mapping operations, in one embodiment, the inverse mapping function is modelled as a piece-wise linear function, and each line segment is defined on an equi-distant interval of a length equal to a power of 2. In this embodiment, the inverse mapping function is specified by the number of pieces, initial offset value and the slope for each piece. In one example, the slope parameters can be signaled directly in the bitstream. In another example, an initial estimate of the slope parameters can be obtained from the forward mapping function, and the difference between the initial estimate and the actual parameters are signaled.

Abstract: Encoding or decoding a picture part of video information can include using a refinement mode per block where the refinement mode can be based on a refinement parameter. The refinement mode can include a cross-component refinement that can be a cross-component chroma refinement. The refinement mode can include enabling selection per block of a refinement parameter where the refinement parameter can include one or more chroma refinement parameters included in a chroma refinement table.

Abstract: In some chroma formats, monochrome processing is performed for each color component. For example, for 4:0:0, only luma components exist, and all chroma related syntax and code are not used. In addition, for 4:4:4 when separable color plane is activated, the chroma components are treated as independent luma components, and the codec may behave as if no chroma is present at all and no chroma related tools are used. To reduce redundancy in coding parameters related to chroma, in one implementation, a flag indicating the availability of chroma components is coded. In another implementation, inter-related syntax is omitted in an intra-only coding mode for video data. In addition, slice level control of LMCS is provided.

Abstract: A method for decoding a picture block is disclosed. The decoding method comprises: reconstructing reference picture from another reference picture of a decoder picture buffer of a first layer of a multi-layered stream and from data decoded from a second layer of said multi-layered stream and storing said reference picture in a decoder picture buffer of said second layer, wherein said reference picture is indicated as not to be displayed; decoding a flag indicating that a subsequently decoded picture of the second layer is not using any inter-layer prediction; and reconstructing a picture block of said subsequently decoded picture at least from said reference picture.

Abstract: A method for encoding a block of a picture is disclosed. The method comprises for at least one sample of the block and for one current component: obtaining a prediction value; determining a mapped residual value from a source value of the sample and from the prediction value responsive to a mapping function; and encoding the mapped residual value into a bitstream; wherein the mapping function is derived to obtain at least one of a reduction of a bit cost of the bitstream for a given quality of reconstruction or an increase of quality of reconstruction for a given bit cost of the bitstream.

Abstract: A method for reconstructing a block of an image, said block comprising a plurality of components and being predictively encoded from a reference block, includes if a single quantized residual block is used to jointly encode at least two components of the plurality of components, deriving at least one quantization matrix from a plurality of scaling lists each defined for one component of the plurality of components; and, applying one of the at least one derived quantization matrix to the single quantized residual block to obtain a reconstructed residual block for each of the at least two components.

Abstract: Encoding or decoding picture information can involve determining a first scaling factor varying with a first granularity to scale a chroma prediction residual associated with chroma information included in the picture information; determining a second scaling factor varying with a second granularity finer than the first granularity; scaling the chroma prediction residual based on a combination of the first scaling factor and the second scaling factor to provide a scaled chroma prediction residual with the second granularity; and encoding or decoding at least a portion of the picture information based on the scaled chroma prediction residual.

Abstract: Compression technology comprises deriving chroma quantization parameter (Qpc) based on luma Qp using luma-to-chroma Qp mapping table. Such a table may be shared by the encoder and the decoder. However, in some cases, signaling such a table in the data stream instead of having it fixed by a standard may be advantageous. The syntax used to encode, signal and decode this table has a cost in terms of bitrate. The present principles propose to signaling of a luma-to-chroma mapping table in the data stream according to different embodiments.

Abstract: Methods and apparatus provide mapping functions for video encoding or decoding by replacing a pivot point of a uniformly sampled inverse mapping function by another pivot point not located on an original non-uniformly sampled inverse mapping function. In one embodiment a last pivot point of the inverse mapping function is extended based on a previous slope whose curve is plotted between two previous pivot points or based on the preservation of the slope which is dual to the existing slope of the equivalent section in the forward mapping function. Syntax is provided that assists the mapping and inverse mapping and clipping.

Abstract: A method for encoding a block of a picture is disclosed. The method comprises for at least one sample of the block and for one current component: —obtaining a prediction value; —determining a mapped residual value from a source value of the sample and from the prediction value responsive to a mapping function; and —encoding the mapped residual value into a bitstream; wherein the mapping function is derived to obtain at least one of a reduction of a bit cost of the bitstream for a given quality of reconstruction or an increase of quality of reconstruction for a given bit cost of the bitstream.

Abstract: A method for decoding a block of a picture represented in a current HDR/WCG format is disclosed. The method comprises receiving a bitstream representative of a coded block of picture, an indication representative of a default d QP table (index_d QP_table), an indication representative of a QP offset (slice_qp_delta); determining a quantization parameter responsive to the current format based on the default d QP table and the QP offset; decoding the coded block of a picture using the determined QP. Corresponding encoding method, transmitting method, decoding device, encoding device and transmitting device are disclosed. Besides an embodiment relative to adapting generic codec parameters to any HDR/WCG format as done for d QP table is also disclosed.

Abstract: Reshaping can be used to better exploit the sample value distribution of video data. When reshaping is used inside the coding loop, forward mapping is applied to prediction signals from intra or inter prediction, and inverse mapping is applied to reconstructed signals. To simplify the inverse mapping operations, in one embodiment, the inverse mapping function is modelled as a piece-wise linear function, and each line segment is defined on an equi-distant interval of a length equal to a power of 2. In this embodiment, the inverse mapping function is specified by the number of pieces, initial offset value and the slope for each piece. In one example, the slope parameters can be signaled directly in the bitstream. In another example, an initial estimate of the slope parameters can be obtained from the forward mapping function, and the difference between the initial estimate and the actual parameters are signaled.

Abstract: Encoding or decoding a picture part of video information can include using a refinement mode per block where the refinement mode can be based on a refinement parameter. The refinement mode can include a cross-component refinement that can be a cross-component chroma refinement. The refinement mode can include enabling selection per block of a refinement parameter where the refinement parameter can include one or more chroma refinement parameters included in a chroma refinement table.