Abstract: 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.

Abstract: The invention is related to a method and a device for encoding of a bit sequence. Said method comprises generating, for each run of Ones comprised in the bit sequence, a unary representation of length of the respective run of Ones, generating a first sequence by concatenating the generated unary representations of lengths of runs of Ones, generating, for each run of Zeroes comprised in the bit sequence, a unary representation of the length of the respective run of Zeroes, generating a second sequence by concatenating the generated unary representations of lengths of runs of Zeroes, and bit plane encoding the generated first and second sequence of unary representations. In most cases, overall entropy of bit planes of unary representations of run lengths is smaller than entropy of the bit sequence. Thus, more compact encoding can be achieved.

Abstract: The invention is related to lossless compression of prefix-suffix-codes wherein a prefix comprises unary code, and to corresponding decompression. The method for lossless compressing prefix-suffix-codes comprises the steps of forming a first contiguous bit sequence from the prefixes, and lossless compressing the first contiguous bit sequence by removing redundancy related to the difference between the first value's frequency in the first contiguous bit sequence and the second value's frequency in the first contiguous bit sequence. Bit values are unevenly distributed in the prefixes while distribution of bit values in the suffixes is more even. Therefore, better compression is achievable if the prefixes are compressed separately.

Abstract: In known image compression, following quantisation, a very sparse distribution of significant (i.e. non-zero) amplitude coefficients of the transformed image signal may be obtained while most quantised coefficients are zeros. A costly task for a transform-based image compression in terms of resulting overall data rate is to record the locations of such significant coefficients within the coding blocks. In quartation processing, a ‘significant square’ (containing at least one non-zero amplitude coefficient in the coefficient block) is recursively divided into four smaller squares until single significant coefficients are reached, and the significance statuses of all generated squares are encoded. However, for some distribution patterns encoding the x-y-coordinates of the significant coefficients as binary numbers will lead to less coding cost.

Abstract: A method for encoding a sequence of integers includes identifying a contiguous sub-sequence in the sequence of integers wherein the sub-sequence includes interrelated integers having a same prefix when being variable length encoded and an independent last integer. A code for the contiguous sub-sequence is formed using a code for an indication of the number of interrelated integers in the contiguous subsequence, a code of a prefix indication, and the suffixes of variable length codes of the integers in the contiguous sub-sequence. In doing so, a single prefix is sufficient instead of n individual prefixes.

Abstract: The invention is related to a method and a device for encoding of a bit sequence. Said method comprises generating, for each run of Ones comprised in the bit sequence, a unary representation of length of the respective run of Ones, generating a first sequence by concatenating the generated unary representations of lengths of runs of Ones, generating, for each run of Zeroes comprised in the bit sequence, a unary representation of the length of the respective run of Zeroes, generating a second sequence by concatenating the generated unary representations of lengths of runs of Zeroes, and bit plane encoding the generated first and second sequence of unary representations. In most cases, overall entropy of bit planes of unary representations of run lengths is smaller than entropy of the bit sequence. Thus, more compact encoding can be achieved.

Abstract: The invention is related to a method for encoding a sequence of integers, to a storage device and to a signal carrying such encoded sequence and to a method for decoding such encoded sequence. Said method comprises the steps of identifying a contiguous sub-sequence in the sequence of integers wherein said sub-sequence comprises interrelated integers having a same prefix when being variable length encoded and an independent last integer, and forming a code for the contiguous sub-sequence by help of code for an indication of the number of interrelated integers in said contiguous subsequence, a code of a prefix indication and the suffixes of variable length codes of the integers in the contiguous is sub-sequence. Thus, if there are n integers of which each is encoded with the same prefix then, instead of n individual prefixes for the integers, a single prefix for the contiguous subsequence is sufficient.