Abstract: The present invention is related to video coding and decoding, in particular HEVC RExt that define the adaptive residual color transform, Adaptive RCT, of a residue of pixels. Compared to HEVC RExt where Adaptive RCT is signalled at Coding Unit level, embodiments of the invention propose to signal it in the bitstream in association with two or more coding units forming the image. In other words, it is signalled at a level higher than the CU level, for instance at sequence or frame or slice or tile or coding tree block level. In addition, various flags at this higher level make it possible to generically define the applying or not of RCT for various respective coding modes, for instance Inter coding mode, Intra Block Copy coding mode or Intra coding mode where Chroma and Luma modes are the same. Such approach makes it possible to reduce the amount of evaluations to be performed.

Abstract: A method of encoding a sequence of images comprises performing area-by-area loop filtering on at least one image of the sequence and disabling such area-by-area loop filtering on at least one other image of the sequence. The images of the sequence are associated with respective levels from a plurality of levels, the levels corresponding to different respective rate-distortion balances or to different image qualities, and the images on which the area-by-area loop filtering is disabled are determined in dependence upon the levels.

Abstract: The value of a quantization parameter for at least one second color component of an image or image portion is determined using a current color format among several possible color formats. The determination comprises the steps of selecting at least one function associated with a possible color format, and determining the value of the quantization parameter for the second color component by applying said at least one function to a value of an intermediate quantization parameter which is based on the value of the quantization parameter of the first color component of the image or image portion. The at least one function is selected independently from the current color format.

Abstract: The invention relates to the encoding and decoding of texture mapping data of a textured 3D object. A 3D object is usually represented by connectivity, geometry and property data. The texture data, belonging to the property data, include a texture image; a texture coordinates table having entries, each entry defining coordinates in the texture image; and texture indexes associating each vertex of a polygon in the 3D object with an entry in the texture coordinates table. The present invention proposes to search for and delete entry duplicates from the texture coordinates table. To reduce encoding complexity, the search and deletion are based on the connectivity data. This is to exploit redundancies between the mesh connectivity for the polygons within the 3D object and the texture connectivity for the texture polygons within the texture image.

Abstract: An encoding method comprises obtaining a target number of motion information predictors to be used for an image portion to encode and generating a set of motion information predictors using the obtained target number.

Abstract: An encoding method comprises obtaining a target number of motion information predictors to be used for an image portion to encode and generating a set of motion information predictors using the obtained target number.

Abstract: An encoding method comprises obtaining a target number of motion information predictors to be used for an image portion to encode and generating a set of motion information predictors using the obtained target number.

Abstract: The invention concerns a method, device, and computer program for motion vector prediction in scalable video encoder and decoder. It concerns the process to determine motion information predictor in the enhancement layer of a scalable encoding scheme also known as motion derivation process. It comprises a correction of the position in the reference layer used to pick-up the more relevant motion information available due to the compression scheme. Accordingly, motion information prediction is improved.

Abstract: Encoding and decoding of property data, such as colour values, associated with vertices forming 3D objects. From an analysis of connectivity data, a spiral-like scanning path of the vertices within the 3D model is obtained. The colour values are mapped to a 2D image, each attribute value to a pixel. Next, the mapped 2D image is encoded. To increase redundancies in the 2D image, the spiral-like path is split into path segments, each forming a turn in the spiral; each path segment is assigned to a respective line of the 2D image; and the colour values of each path segment are mapped, in the same order, to the respective line of the 2D image. Successive lines in the 2D image thus contain the colour values of neighbouring vertices in the 3D object, and a better encoding can be achieved.

Abstract: The present invention concerns a method of encoding an image, the image comprising a plurality of coding elements made of blocks of pixels, each block of pixels being encoded according to a coding mode out of a plurality of coding modes, the method comprising for each block of pixel to be encoded determining the coding mode to be used for the encoding of a given block of pixels by sequentially evaluating some coding modes in the plurality of coding modes; wherein the method comprises evaluating Inter coding modes and fast IBC coding modes; and no residue-test is conducted between the evaluation of the Inter coding mode and the evaluation of the fast IBC mode. Accordingly, some good predictors may be found more rapidly and the whole encoding process is speed up.

Abstract: An encoding method comprises obtaining a target number of motion information predictors to be used for an image portion to encode and generating a set of motion information predictors using the obtained target number. The set is generated by: obtaining a first set of motion information predictors; if the first set includes duplicates then adding one or more non-duplicate motion information predictor(s).

Abstract: A method for deriving a set of enabled coding modes relative to the encoding of an image or image portion which forms part of an image sequence. The method comprises: obtaining information associated with coding modes of one or more previously encoded images of the sequence, and selectively enabling for the current image or image portion, coding modes based on said obtained information.

Abstract: The invention concerns a method and a device for processing images, e.g. for encoding or decoding the images into or from a bitstream, using a palette prediction mode as defined in HEVC SCC. The images are split into hierarchical coding structures.

Abstract: The present invention provides a method and a device for coding and decoding at least a part of an image comprising a plurality of samples, each sample comprising at least two components, and the encoded image comprising at least one filtering parameter. The filtering comprises using at least one filtering parameter as a common filtering parameter for filtering both the first component and the second component of a reconstructed sample.

Abstract: The present invention is related to video coding and decoding, in particular HEVC SCC that define a palette coding mode. In conventional palette modes, the block of levels built from the Coding Unit and from the palette is encoded using syntax elements, such as the “Pred mode” element, the optional “Level” element and the “Run” element defining the number of successive indexes of the block of indexes that are concerned by an operation defined by the “Pred mode” element and the optional “Level” element. In improved embodiments of the invention, the last “Run” element for the Coding Unit uses a particular up-to-end codeword, instead of a codeword associated with a defined number of successive indexes, in order to indicate to perform the operation for the indexes at all remaining block positions up to the end of the block of indexes, regardless the number of the remaining block positions, are concerned.

Abstract: The present invention provides a method and a device for coding and decoding at least a part of an image comprising a plurality of samples, each sample comprising at least two components, and the encoded image comprising at least one filtering parameter. The filtering comprises using at least one filtering parameter as a common filtering parameter for filtering both the first component and the second component of a reconstructed sample.

Abstract: The present invention provides a method and a device for coding and decoding at least a part of an image comprising a plurality of samples, each sample comprising at least two components, and the encoded image comprising at least one filtering parameter. The filtering comprises using at least one filtering parameter as a common filtering parameter for filtering both the first component and the second component of a reconstructed sample.

Abstract: The invention relates to encoding an image of a video stream according a coding mode selected among several that comprises one using reconstructed pixel blocks of the image to be encoded, where blocks of the image to be encoded are predicted as a function of a weighted prediction method based on a reference image. After having determined whether or not a first portion of the image to be encoded, that belongs to a set reference images, is to be used for encoding a second portion of the image to be encoded, the determination being based on a parameter whose value depends on the coding mode to be used for encoding the second portion of the image to be encoded, weighted prediction information is signaled if the first portion of the image to be encoded, that belongs to the set of reference images, is not used for encoding the image.

Abstract: The invention relates to lossless encoding of pixel blocks. To apply the Palette coding mode, an input 4:2:0 block is up-sampled into a 4:4:4 block. Each 4:4:4 pixel is usually lossless encoded using a fully matching entry from the palette, thus being sub-optimal in terms of rate. This is mainly because lossless encoding is still used even for Chromas that have no impact on the decoded output image. To improve this situation, the invention provides that encoding the up-sampled 4:4:4 block includes encoding a 4:4:4 pixel corresponding to a 4:2:0 input pixel without Chromas, using a palette entry different from the 4:4:4 pixel. A lossy matching counter-intuitively does not provide losses in the decoded output image, since it is limited to Chromas discarded in the 4:2:0 block. Less palette entries are thus required, saving indexes and thus reducing the encoding rate.

Abstract: The present invention relates to encoding an image of a video stream according to at least one coding mode selected among a plurality of coding modes used to encode images of the video stream, where blocks of the image to be encoded are predicted as a function of at least one reference image from a set of at least one reference image, the at least one reference image comprising at least a reconstructed spatial portion of the image to be encoded and at least a low resolution portion of the image to be encoded, the choice between a reconstructed spatial sub-portion or a low resolution sub-portion to be used for encoding a block of the image to be encoded being determined as a function of a control parameter.