Abstract: Provided is a method extracts a merge index from a bit stream, constructs a merge candidate list using available spatial and temporal merge candidates, selects a merge predictor among merge candidates using the merge index, and sets motion information of the merge predictor as motion information of the current prediction unit. The temporal merge candidate includes a reference picture index and a motion vector, and a motion vector of a temporal merge candidate block of a temporal merge candidate picture is set as the motion vector of the temporal merge candidate. Accordingly, the coding efficiency of the motion information is improved by including various merge candidates. Also, the computational complexity of an encoder and a decoder is reduced maintaining improvement of coding efficiency by adaptively storing motion information of reference picture and adaptively generating a temporal merge candidate.

Abstract: An image decoding device includes a processor, and a non-transitory computer-readable medium having stored thereon instructions that, when executed, cause the processor to perform a method that use quantization parameters of left and above coding units to derive a quantization parameter predictor used for generating a residual block.

Abstract: A method is provided for reconstructing video data using a merge mode. A merge list is constructed using available spatial and temporal merge candidates. A merge candidate on the merge list corresponding to a merge index is determined as motion information of a current prediction unit;. A predicted block of the current prediction unit is generated using the motion information. A transformed block is generated by inverse-quantizing a block of quantized coefficients using a quantization parameter. A residual block is generated by inverse-transforming the transformed block. A reconstructed block is generated using the predicted block and the residual block.

Abstract: Provided is a method that derives an intra prediction mode of a prediction unit, selects an inverse scan pattern of a current transform unit among a diagonal scan, a vertical scan and a horizontal scan based on the intra prediction mode and a size of the transform unit, and generates a quantized block by inversely scanning significant flags, coefficients signs and coefficient levels according to the selected inverse scan pattern. If the transform unit is larger than a predetermined size, multiple subsets are generated and inversely scanned. Therefore, the amount of coding bits of the residual block is reduced by determining the scan pattern based on the size of the transform unit and the intra prediction mode, and by applying the scan pattern to each subset. Also, the signaling bits decreases by generating MPM group adaptively according to the neighboring intra prediction modes.

Abstract: A method of decoding an intra prediction mode, can include reconstructing an intra prediction mode group indicator and a prediction mode index, constructing an MPM group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current block, determining an intra prediction mode of the MPM group corresponding to the prediction mode index as the intra prediction mode of the current block when the intra prediction mode group indicator indicates that the intra prediction mode of the current block belongs to the MPM group and determining the intra prediction mode of the current block using the prediction mode index and the three intra prediction modes of the MPM group when the intra prediction mode group indicator indicates that the intra prediction mode of the current block does not belong to the MPM group.

Abstract: Provided is a method derives a reference picture index and a motion vector of a current prediction unit, generates a prediction block of the current prediction unit using the reference picture index and the motion vector, generating a residual block by inverse-scan, inverse-quantization and inverse transform, and generates reconstructed pixels using the prediction block and the residual block. Prediction pixels of the prediction block is generated using an interpolation filter selected based on the motion vector. Accordingly, the coding efficiency of the motion information is improved by including various merge candidates. Also, the computational complexity of an encoder and a decoder is reduced by selecting different filter according to location of the prediction pixels determined by the motion vector.

Abstract: Provided is a method that derives an intra prediction mode of a prediction unit, determines a size of a current block using transform size information, generates a prediction block of the current block according to the intra prediction mode, generating a residual block of the current block according to the intra prediction mode and generating a reconstructed block of the current block using the prediction block and the residual block. The sizes of the prediction block and the residual block are set equal to a size of a transform unit. Therefore, the distance of intra prediction becomes short, and the amount of coding bits of residual block is reduced by generating a prediction block very similar to original block. Also, the signaling bits required to signal intra prediction mode decrease by generating MPM group adaptively according to the neighboring intra prediction modes.

Abstract: A method of generating a reconstructed block is provided. A mode group indicator and a prediction mode index are entropy-decoded. A quantized block is inversely quantized using a quantization parameter and a quantization matrix to generate a transform block. The transform block is inversely transformed to generate a residual block. A Most Probable Mode (MPM) group including three intra prediction modes is constructed using a left intra prediction mode and an above intra prediction mode of a current prediction unit. An intra prediction mode of the current prediction unit is derived using the mode group indicator and the prediction mode index. Reference pixels of a current block are adaptively filtered according to a size of a transform unit and the intra prediction mode. The prediction block is generated according to the intra prediction mode. The reconstructed block is generated using the prediction block and the residual block.

Abstract: Provided is a method checks availability of spatial merge candidates and a temporal merge candidate, constructs a merge candidate list using available spatial and temporal merge candidates, and adds one or more candidates if the number of available spatial and temporal merge candidates is smaller than a predetermined number. The spatial merge candidate is motion information of a spatial merge candidate block, the spatial merge candidate block is a left block, an above block, an above-right block, a left-below block or an above-left block of the current block, and if the current block is a second prediction unit partitioned by asymmetric partitioning, the spatial merge candidate corresponding to a first prediction unit partitioned by the asymmetric partitioning is set as unavailable. Therefore, the coding efficiency of motion information is improved by removing unavailable merge candidates and adding new merge candidates from the merge list.

Abstract: Provided is a method checks availability of spatial merge candidates and a temporal merge candidate, constructs a merge candidate list using available spatial and temporal merge candidates, and adds one or more candidates if the number of available spatial and temporal merge candidates is smaller than a predetermined number. The spatial merge candidate is motion information of a spatial merge candidate block, the spatial merge candidate block is a left block, an above block, an above-right block, a left-below block or an above-left block of the current block, and if the current block is a second prediction unit partitioned by asymmetric partitioning, the spatial merge candidate corresponding to a first prediction unit partitioned by the asymmetric partitioning is set as unavailable. Therefore, the coding efficiency of motion information is improved by removing unavailable merge candidates and adding new merge candidates from the merge list.

Abstract: Provided is a method that derives an intra prediction mode of a prediction unit, selects an inverse scan pattern of a current transform unit among a diagonal scan, a vertical scan and a horizontal scan based on the intra prediction mode and a size of the transform unit, and generates a quantized block by inversely scanning significant flags, coefficients signs and coefficient levels according to the selected inverse scan pattern. If the transform unit is larger than a predetermined size, multiple subsets are generated and inversely scanned. Therefore, the amount of coding bits of the residual block is reduced by determining the scan pattern based on the size of the transform unit and the intra prediction mode, and by applying the scan pattern to each subset. Also, the signaling bits decreases by generating MPM group adaptively according to the neighboring intra prediction modes.

Abstract: Provided is a method that derives a chroma intra prediction mode of a prediction unit, determines a size of a current chroma block using luma transform size information, generates a chroma prediction block of the current chroma block using the chroma intra prediction mode, generates a chroma residual block of the current chroma block using the chroma intra prediction mode and a chroma quantization parameter, generates a chroma reconstructed block adding the chroma prediction block and the chroma residual block, and the chroma quantization parameter is generated using a luma quantization parameter and information indicating the relationship between the luma quantization parameter and the chroma quantization parameter. Therefore, the coding efficiency is improved by adjusting the chroma quantization parameter per picture. Also, the amount of bits for transmitting the luma and chroma quantization parameters is reduced by encoding the luma quantization parameter using neighboring luma quantization parameters.

Abstract: Provided is a method that derives an intra prediction mode of a prediction unit, selects an inverse scan pattern of a current transform unit among a diagonal scan, a vertical scan and a horizontal scan based on the intra prediction mode and a size of the transform unit, and generates a quantized block by inversely scanning significant flags, coefficients signs and coefficient levels according to the selected inverse scan pattern. If the transform unit is larger than a predetermined size, multiple subsets are generated and inversely scanned. Therefore, the amount of coding bits of the residual block is reduced by determining the scan pattern based on the size of the transform unit and the intra prediction mode, and by applying the scan pattern to each subset. Also, the signaling bits decreases by generating MPM group adaptively according to the neighboring intra prediction modes.

Abstract: An image decoding device is provided which includes an intra prediction module for reconstructing an intra prediction mode and creating a prediction block of a current block or a sub block, an inverse scanning module for converting residual signals into a quantization block, an inverse quantization module for inversely quantizing the quantization block, and an inverse transform module for inversely-transforming the inversely-quantized block. A quantization parameter predictor for deriving the quantization parameter is created using quantization parameters of a left coding unit and a top coding unit of a current coding unit. Therefore, it is possible to improve image quality by adaptively adjusting a quantization parameter of a current block depending on the size of a coding unit and enhance compression efficiency of an image by effectively encoding/decoding the quantization parameter to reduce the number of bits required for transmitting the quantization parameter.

Abstract: Provided is a method extracts a merge index from a bit stream, constructs a merge candidate list using available spatial and temporal merge candidates, selects a merge predictor among merge candidates using the merge index, and sets motion information of the merge predictor as motion information of the current prediction unit. The temporal merge candidate includes a reference picture index and a motion vector, and a motion vector of a temporal merge candidate block of a temporal merge candidate picture is set as the motion vector of the temporal merge candidate. Accordingly, the coding efficiency of the motion information is improved by including various merge candidates. Also, the computational complexity of an encoder and a decoder is reduced maintaining improvement of coding efficiency by adaptively storing motion information of reference picture and adaptively generating a temporal merge candidate.

Abstract: Provided is a method that constructs an MPM group including three intra prediction modes, determines the intra prediction mode of the MPM group specified by the prediction mode index as the intra prediction mode of the current prediction unit if the mode group indicator indicates the MPM group, and derives the intra prediction mode of the current prediction unit using the prediction mode index and the three prediction modes of the MPM group if the mode group indicator does not indicate the MPM group. Accordingly, additional bits resulted from increase of a number of intra prediction mode are effectively reduced. Also, an image compression ratio can be improved by generating a prediction block similar to an original block.

Abstract: Provided is a method that restores a differential quantization parameter of a current coding unit, generates a quantization parameter predictor of the current coding unit using one or two quantization parameters of a left quantization parameter, an above quantization parameter and a previous quantization parameter and generates a quantization parameter of the current coding unit using the differential quantization parameter and the quantization parameter predictor, wherein a minimum size of quantization unit is adjusted per picture. Therefore, the complexity of the encoding and decoding apparatus is reduced by adjusting the minimum size of the quantization unit. Also, coding efficiency is improved by encoding the quantization parameter using neighboring quantization parameters and by signaling the minimum size of the quantization unit per picture.

Abstract: A method of decoding an intra prediction mode, can include reconstructing an intra prediction mode group indicator and a prediction mode index, constructing an MPM group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current block, determining an intra prediction mode of the MPM group corresponding to the prediction mode index as the intra prediction mode of the current block when the intra prediction mode group indicator indicates that the intra prediction mode of the current block belongs to the MPM group and determining the intra prediction mode of the current block using the prediction mode index and the three intra prediction modes of the MPM group when the intra prediction mode group indicator indicates that the intra prediction mode of the current block does not belong to the MPM group.

Abstract: Provided is a method that constructs an MPM group including three intra prediction modes, determines the intra prediction mode of the MPM group specified by the prediction mode index as the intra prediction mode of the current prediction unit if the mode group indicator indicates the MPM group, and derives the intra prediction mode of the current prediction unit using the prediction mode index and the three prediction modes of the MPM group if the mode group indicator does not indicate the MPM group. Accordingly, additional bits resulted from increase of a number of intra prediction mode are effectively reduced. Also, an image compression ratio can be improved by generating a prediction block similar to an original block.

Abstract: An apparatus of decoding an image is discussed. The apparatus can include an intra prediction unit for generating a prediction block using an intra prediction mode of a current prediction unit; an inverse scanning unit for inversely scanning significant flags, coefficient signs and coefficient levels according to an inverse scan pattern which is selected based on the intra prediction mode and a size of a transform unit to generate a quantized block; an inverse quantization unit for inversely quantizing the quantized block using a quantization parameter and a quantization matrix to generate a transform block; an inverse transform unit for inversely transform the transform block to generate a residual block; and an adder for adding the prediction block and the residual block to generate a reconstructed block.