Abstract: The embodiments of the present invention relate to compression of parameters of an encoded texture block such that an efficient encoding is achieved. Index data is used as an example of parameters to be encoded. Accordingly, encoding the index data is achieved by predicting the index data, wherein the prediction is done in the pixel color domain, where changes often are smooth, instead of in the pixel index domain where the changes vary a lot. Hence, according to embodiments of the present invention the index data is predicted from previously predicted neighboring pixels taking into account that the base value and a modifier table value are known. When the index value is predicted the real index value can be decoded with the prediction as an aid. Since this way of predicting the index provides a very good prediction, it lowers the number of bits needed to represent the pixel index.

Abstract: A compressed pixel block (400) is decompressed by defining multiple available property values. At least one reference point relative the pixel block (300) is identified based on a reference codeword (410) of the compressed pixel block (400). Pixel indices of the pixels (310) are determined based on the respective positions of pixels (310) in the pixel block (300) relative the at least one reference point. These pixel indices are used for selecting among the multiple defined property values. The selected property values are then assigned to pixels (310) to be decompressed based on their determined pixel indices.

Abstract: Encoder, decoder and methods for intra coding of video. The method in the decoder relates to decoding of an intra coded block IZ having a number N of neighboring blocks CU1-CUN. When at least one block CUk of the number of neighboring blocks is unavailable for intra prediction, pixel values for spatial positions covered by CUk are estimated based on at least one pixel value of at least one of blocks CUk?m and CUk+p within the range [CU1-CUk?1, CUk+1-CUN] of blocks, which is available for intra prediction. Further, the block IZ is decoded, using the estimated pixel values for prediction, thus generating a block Z of pixels. k, m and p are integers, and 1?k?N; 1?m?k; and 1?p?N?k; and N is a positive integer.

Abstract: An image (1) is decomposed into multiple superblocks (20, 22), each encompassing multiple pixel blocks (30A-30D, 32A-32D) having multiple pixels (40). The property values of a superblock (20) is fixed rate compressed to get a compressed block having a target bit length. The compressed block is stored in the memory locations (310, 320) assigned to the multiple pixel blocks (30A-30D) encompassed by the superblock (20) to thereby get multiple copies of the compressed block in the memory (300). The multiple copies collectively constitute a compressed representation of the superblock (20). When accessing a compressed block in a memory location (310) using random access during decoding, property values for neighboring pixel blocks (30B-30D) are obtained for free without the need for any further memory access.

Abstract: A tile of pixels is encoded by variable length encoding at least a first block of pixels into a first sequence of symbols and a second block of pixels into a second sequence of symbols. The symbols of the first and second sequences are co-organized into a combined sequence of symbols in which the symbols of the first sequence are readable in a first reading direction and at least a portion of the symbols in the second sequence are readable in a second, opposite reading direction. The encoding of the tile to form one or more combined sequences significantly reduces the bandwidth requirements when writing the tile to a pixel value buffer. The co-organization of the first and second sequences enables parallel reading and decoding of the first and second sequences from the pixel value buffer, thereby reducing any decoding latency.

Abstract: A slice granularity representing a hierarchical level for slice boundary alignment in a picture (1) comprising at least one slice (10, 12) of coding units (20-56) is used together with coordinates of the coding units (20-56) in a slice (10, 12) to determine those coding units (30, 46A, 46B, 36) that potentially could constitute an end of a slice (10, 12). Each coding unit (30, 46A, 46B) except one of the determined coding units (30, 46A, 46B, 36) is assigned an end-of-slice flag with a first value, while the one determined coding unit (36) gets an end-of-slice flag with a second value. The end-of-slice flags are used during decoding for identifying the end of a slice (10, 12). The embodiments provide an efficient end-of-slice flag signaling by merely assigning such flags to some of the coding units (30, 46A, 46B, 36) in the picture (1), while other coding units need no associated flag.

Abstract: A first and a second data value are co-compressed by generating a sequence of symbols having a most significant symbol that is the most significant symbol of a compressed representation of the first data value and a least significant symbol that is the most significant symbol of a compressed representation of the second data value. The compressed representation of the first data value corresponds to at least a portion of the symbols of the sequence of symbols starting from the most significant symbol and extending towards the least significant symbol in a first reading direction. The compressed representation of the second data value also corresponds to at least a portion of the symbols of the sequence of symbols, however, starting from the least significant symbol and extending in an opposite reading direction towards the most significant symbol.

Abstract: The present invention relates to methods and arrangements for compressing images. The invention is based on the fact that edge blocks contain much information in one direction (across the edge), but very little information in the other direction (along the edge). By encoding edges explicitly, it is possible to obtain a high quality to a very low cost for many blocks. A block is encoded by first specifying the orientation of the edge in the block, and then specifying the profile across the edge using a function with a small number of parameters.

Abstract: A compressing of a texel block (10) consisting of two texel sub-blocks (12, 14) involves determining respective value codewords (31, 32) and table codewords (33, 34) for the two texel sub-blocks (12, 14). The value codewords (31, 32) represent respective base texel values and the table codewords (33, 34) represent respective modifier sets comprising multiple value modifiers for modifying the base texel value associated with the given texel sub-block (12, 14). Each texel (20) in the texel block (10) is assigned a texel index associated with one of the value modifiers of the modifier set for the texel sub-block (12, 14) to which the texel (20) belongs or indicates that the base texel value of the other texel sub-block (12, 14) is to be used for the texel (20).

Abstract: Embodiments relate to compression and decompression of textures. A texel block (10) is compressed by specifying two major directions in the texel block (10) and defining the profiles of how the texel values change along the respective directions. The resulting compressed texel block (30) comprises two value codewords (31, 32), two line codewords (35-38) and a function codeword (33, 34). The two value codewords (31, 32) are employed to calculate two texel values for the texel block (10). The line codewords (35-38) are employed to determine equations of two lines (20, 22) coinciding with the two major directions in the texel block (10). Signed distances are calculated for each texel (12) from the texel position in the texel block (10) and to the two lines (20, 22). The signed distances are input to a function defined by the function codeword (33, 34) to output two values from which weights are calculated and applied to the two texel values in order to get a representation of the texel value of a texel (12).

Abstract: A pixel block is compressed by providing a respective color component prediction for each pixel in the block. A difference between color components of two neighboring pixels is calculated and compared to a threshold. If the difference is smaller than the threshold, the prediction is calculated based on a first linear combination of the color components of these two neighboring pixels. However, if the difference exceeds the threshold, a second or third linear combination of the color components of the neighboring pixels is employed in the prediction. A guiding bit associated with the selected linear combination may be used. A prediction error is calculated based on the color component of the pixel and the provided prediction. The compressed block comprises an encoded representation of the prediction error and any guiding bit.

Abstract: A pixel block (300) is losslessly compressed into a candidate compressed block. If the bit length of the candidate block exceeds a threshold value, the property values of the pixels (310-317) in the block (300) are quantized and the quantized values are losslessly compressed into a new candidate compressed block. The procedure is repeated until a candidate compressed block having good image quality and a bit length below the threshold value is found. A compressed representation (400) of the block (300) is determined based on the found candidate compressed block (420) and an identifier (410) of the used quantization parameter.

Abstract: A pixel block is compressed by providing a respective color component prediction for each pixel in the block. A difference between color components of two neighboring pixels is calculated and compared to a threshold. If the difference is smaller than the threshold, the prediction is calculated based on a first linear combination of the color components of these two neighboring pixels. However, if the difference exceeds the threshold, a second or third linear combination of the color components of the neighboring pixels is employed in the prediction. A guiding bit associated with the selected linear combination may be used. A prediction error is calculated based on the color component of the pixel and the provided prediction. The compressed block comprises an encoded representation of the prediction error and any guiding bit.

Abstract: A pixel block (300) is compressed by selecting a start depth value and a restart depth value based on the multiple depth values of the pixels (310-318) in the block (300). A respective plane representation (430) indicative of which plane of a start or restart depth value plane is determined for the pixels (311-318). These representations (430) are employed for selecting a pixel set comprising at least one other pixel (312, 314-317) in the block (300) for a pixel (318) to be encoded. The depth value(s) of the pixel(s) (312, 314-317) in the set are used for determining a prediction of the depth value of the pixel (318). The depth value and the prediction are employed for calculating a prediction error, which is encoded. The compressed pixel block (400) comprises the encoded prediction errors (460), a start value representation (420), a restart value representation (430) and the plane representations (440).

Abstract: Device, computer readable medium, and method for selecting compression modes to be applied in a depth buffer (20).

Abstract: Compression of a pixel block having multiple pixels comprises calculating a respective prediction error for each pixel component of the pixels except a defined starting pixel. Respective minimum number of symbols required for representing the prediction errors are determined and used to select a symbol configuration among multiple different symbol configurations. Each such symbol configuration defines respective numbers of symbols maximally available for the different prediction errors. A compressed representation of the pixel block comprises a configuration identifier of the selected symbol configuration, a representation of the pixel value of the defined starting pixel and representations of the prediction errors calculated for the remaining pixels.

Abstract: The present invention relates to methods and arrangements for compressing images. The invention is based on the fact that edge blocks contain much information in one direction (across the edge), but very little information in the other direction (along the edge). By encoding edges explicitly, it is possible to obtain a high quality to a very low cost for many blocks. A block is encoded by first specifying the orientation of the edge in the block, and then specifying the profile across the edge using a function with a small number of parameters.

Abstract: An image (1) is decomposed into multiple superblocks (20, 22), each encompassing multiple pixel blocks (30A-30D, 32A-32D) having multiple pixels (40). The property values of a superblock (20) is fixed rate compressed to get a compressed block having a target bit length. The compressed block is stored in the memory locations (310, 320) assigned to the multiple pixel blocks (30A-30D) encompassed by the superblock (20) to thereby get multiple copies of the compressed block in the memory (300). The multiple copies collectively constitute a compressed representation of the superblock (20).

Abstract: There is provided a method of selecting PMV candidates, wherein each PMV candidate corresponds to a motion vector used for coding of a previous block, said previous block having a distance from a current block. The method comprises identifying allowed distance values of distances between the current block and the previous block. The method further comprises selecting a set of PMV candidates as a subset of the set of previously coded motion vectors that were used for previous blocks having an allowed distance from the current block.

Abstract: There is provided a method of managing PMV candidates. The method comprises selecting a set of PMV candidates as a subset of the previously coded motion vectors. The method further comprises assigning a code value to each PMV candidate in the set of PMV candidates. The code values vary in length and are assigned to the PMV candidates in order of expected usage such that the PMV candidate having the highest expected usage has one of the shortest code values.