Thomson Licensing

Qu Qing Chen

Zhi Chen

Li Zhu

Kangying Cai

Xiao Dong Gu

Jun Teng

Kang Ying Cai

Tong Zhou

Xiao Zhong Xu

Zhi Bo Chen

3D mesh models are represented by three types of data: connectivity data, geometry data and property data. The surface of a 3D object is a triangle mesh. 3D meshes contain huge amounts of data that need to be compressed efficiently. Additionally to the common world coordinate system for the complete model and local coordinate system for a single triangle, an individual component coordinate system for each connected component is used. The component coordinate system is used to normalize the orientation of the respective component for quantization and de-quantization. This improves the accuracy of encoded 3D mesh models after quantization/de-quantization, particularly if a 3D mesh model comprises one or more distinct components.

Method for encoding/decoding a 3D mesh model that comprises one or more components

An algorithm for efficiently compressing floating-point data in 3D meshes is disclosed. 3D meshes are represented by topology data, geometry data and property data. Geometry data specify vertex locations and are usually represented by floating-point coordinates. While geometry data are usually compressed by quantization, prediction and entropy coding, the present invention uses no prediction. A floating-point number consists of mantissa and exponent, and normally the exponent, sign and mantissa are compressed separately. A method for encoding floating-point formatted data comprises determining if a current floating-point value was previously stored in a memory, storing the current value in the memory if it was not previously stored in the memory, and encoding it. Otherwise, if the current floating-point value was previously stored in a memory, the storage position of the value within the memory is determined and a reference pointing to the storage position is encoded.

Method for encoding floating-point data, method for decoding floating-point data, and corresponding encoder and decoder

3D mesh models are widely used in various applications for representing 3D objects. These models are made of vertices and corresponding triangles, which can be compressed based on prediction and residuals. The present invention improves the accuracy of parallelogram prediction, particularly near sharp features. The proposed 3D mesh model encoding comprises analyzing the spatial or dihedral angles between triangles, clustering triangles with similar or equal dihedral angles, and defining a representative dihedral angle for each cluster. Triangles of each cluster are then encoded relative to individual prediction triangles having the representative dihedral angle according to the cluster. Additionally, the prediction triangle may be mirrored. An indication of the encoding mode is inserted into each vertex of the encoded bitstream. A decoder extracts the encoding mode indication, reconstructs the individual prediction triangles based on the respective representative dihedral angles and performs triangle prediction and reconstruction.

Method and apparatus for encoding 3D mesh models, and method and apparatus for decoding encoded 3D mesh models

The invention is related to encoding an image block of an image using a partitioned block transform. The inventors recognized that applying a texture-pattern associated invertible mapping to the pixels of a first partition, said first partition resulting from partitioning said image block according to a current texture pattern with which said texture-pattern associated invertible mapping is associated, allows for limiting the maximum number of required first 1-D transforms to not exceeding a number of columns in the image block as well as limiting the maximum number of required second 1-D transforms to not exceeding a number of rows in the image block, also. Achieving limitation of maximum required 1-D transforms enables more efficient implementation on hardware and improves encoding performance but also allows for further partitions according to texture patterns which comprise at least one of multiple strips, texture patterns with highly unsymmetrical pixel distribution and non-directional texture patterns.

Texture-pattern-adaptive partitioned block transform

An adaptive video presentation method for automatically presenting a video with stream-embed information based on content analysis of the video on a smaller display with a limited screen size is provided. The method comprises steps of determining a salient object group containing at least one salient object based on perceptual interest value of macroblocks for each frame of said video, extracting a window having a minimum size containing the salient object group for a scene of the video, characterized in that it further comprises steps of comparing size of the extracted window with the smaller display size; and presenting at least a selected area of the extracted window containing at least a part of the salient object group for the scene on the smaller display in different operation modes based on the result of the comparison steps for different motion mode for the scene of the video.

Method and device for adaptive video presentation

When for video coding Intra refresh is used, which inserts Intra coded blocks into previously Inter coded pictures, an efficiently adapted rate control method is required for error resilient video coding. A method for adaptively determining a bit budget for encoding video pictures comprises pre-analyzing each of the pictures of a group of pictures, wherein a relative complexity index is calculated for each picture, allocating bits to the pictures based on their relative complexity index and encoding each of the pictures with the allocated number of bits. The pre-analysis comprises selecting pictures for Intra refresh coding, extracting attention area information from the selected pictures, encoding at least the macroblocks of the attention area using Intra mode, calculating for each picture a complexity index, and calculating from the complexity indices of the pictures of the group a relative complexity index for each picture. Thus, a subjectively better video quality is achieved.

Method and apparatus for adaptively determining a bit budget for encoding video pictures

The invention is made in the technical field of encoding and decoding of bit sequences. The invention proposes a device for compression-encoding an input bit sequence in which Zeroes and Ones occur equally frequent, comprising an XOR gate adapted for receiving pairs of immediately succeeding bits of the input bit sequence as inputs and for outputting further bits of another bit sequence, means for adding a bit to said other bit sequence wherein the added bit is a primary bit which is equal to a primary bit of the input bit sequence or a last bit which is equal to a last bit of the input bit sequence, and means for encoding the other sequence. The XOR gate transforms the input bit sequence into the other bit sequence which comprises more uneven frequencies of occurrence of Zeroes and Ones than the input bit sequence.

Method and device for encoding an input bit sequence and corresponding decoding method and device

A method for compressing a symbol sequence, wherein each symbol may have one out of three or more possible symbol values, said method comprises the steps of modifying the symbol sequence by replacing each run pair, which contains a first run of symbols of a most frequent symbol value and a second run of symbols of a second most frequent symbol value, by a further symbol value not comprised in the three or more possible symbol values, generating a binary sequence comprising all replaced run pairs and compression encoding the binary sequence and the modified symbol sequence.

Method and device for encoding and decoding of symbol sequences wherein each symbol may have one out of three or more possible symbol values

When video sequences are obtained from e.g. news, interviews, conferences and sports matches, flashlight often appears in the video due to photographing. When encoding the video sequence, the intensity changes a lot so that the motion estimation can not find a well-matching block in a previous picture. Accordingly, the video encoder will encode in intra mode and thereby generate much more bits than for the neighboring non-flash pictures. According to the invention, not the real flash picture is encoded in the video sequence but an artificial non-flash or de-flashed picture, and some indications and parameters are inserted into the bit stream to model the flash effect. The decoder can regenerate the flash picture by reconstructing the non-flash picture and then adding the flash effect. The number of bits required for coding flash pictures is thereby significantly reduced.

Method and apparatus for encoding a flash picture occurring in a video sequence, and for decoding corresponding data for a flash picture

The invention concerns a method for embedding video annotation data into a coded video stream. The method comprises the step of &#x2014;encapsulating said video annotation data into a unit, so-called video annotation unit, of the coded video data stream which format corresponds to at least one format used for sending the associated video data, &#x2014;inserting an identifiable synchronizing code enabling the identification of said video annotation unit into the video data stream.

Method for embedding video annotation data into a coded video stream and video recording device

International image or video coding standards uses hybrid coding, wherein a picture is separated into pixel blocks on which predictive coding, transform coding and entropy coding is employed. The transform coding is effective because the prediction error samples are correlated in the frequency domain. However, when the prediction quality is getting better and better, spatial domain coding becomes more effective than transform coding. According to the invention, it is first determined in which corner of a current block the first non-zero amplitude value is located. Based on the related zeros run length value in that block, a pre-defined scan path is selected, i.e. a context-based adaptive scan mode is used.

Method and apparatus for selecting a scan path for the elements of a block in spatial domain picture encoding and decoding

The present invention provides a salience estimation method for object-based visual attention model. The method comprises steps of segmenting the image into a plurality of objects to be estimated, extracting feature maps for each segmented object, calculating the saliences of each segmented object in a set of circles defined around a center pixel of the object based on the extracted feature maps, and integrating the saliences of each segmented object in all circles in order to achieve an overall salience estimation for each segmented object. The present invention is much more human vision inosculated and of low computing complexity.

Salience estimation for object-based visual attention model

In known video coding standards there are basically three types of pictures: I, P and B. Video sequences are usually coded in a group of picture structure wherein several P or B pictures are coded following one I picture. However, this GOP structure has some disadvantages with respect to error resilience and storage medium recording. If a P picture is lost e.g. due to transmission channel error, then the subsequent P pictures can not be reconstructed correctly, and the error will propagate temporally and cause unpleasing artifacts. This GOP structure is designed for forward play only and makes complicated a reverse play operation. According to the invention, a reversible GOP structure is used for the video encoding and decoding. The RGOP structure contains both, a forward encoding chain and a backward encoding chain. Each picture in the RGOP structure is assigned to only one of these chains and the video pictures of adjacent RGOP chains are interleaved.

Method and apparatus for encoding groups of pictures of a video sequence, each of said groups including an intra encoded picture and more than two encoded pictures

The frame following a scene cut is usually coded as an I picture. In CBR encoding, the encoder will try to keep the bit rate constant, which will often cause serious picture quality degradation at scene changes. In VBR encoding, more bits will be allocated to the first frame of the new scene and the bit rate will increase significantly for a short time. Therefore subsequent frames must be coded in 'skipped' mode, which will often cause jerk artifacts. According to the invention, in each frame belonging to a scene change period, areas are determined that have different human attention levels. In the frames (n&#x2212;1, n&#x2212;2, n&#x2212;3) located prior to the first new scene frame, to the areas having a lower attention level less bits are assigned than in the default encoding, and in the frames (n, n+1, n+2) located at and after the scene cut the thus saved bits are additionally assigned to the areas having a higher attention level.

Method and apparatus for adapting a default encoding of a digital video signal during a scene change period

Optimised bit allocation is important in video compression to increase the coding efficiency, i.e. to make optimum use of the available data rate. In view of the human visual system, a human usually pays more attention to some part of a picture rather than to other parts of that picture. Therefore the bit allocation should be optimised for different-attention picture areas (GOB). The inventive distortion-driven bit allocation scheme allocates the coding/decoding error distortion to picture areas consistently with the human visual system, and satisfies the constraint of bit rate as well. The invention uses a distortion/bitrate/rhoquantization parameter histogram analysis. Based on corresponding tables (D[QP], R[QP] and &#x3c1;[QP]), the relationships between quantization parameter, rate, distortion and percentage of non-zero coefficients for the different-attention areas are determined (PREALUTI, DISALL, RALL). Thereafter a rho-domain bit rate control is used (RDBALL) for calculating the bit allocation inside each group of macroblocks.

Growing community of inventors

Beijing, China

Qu Qing Chen