Abstract: An image encoding method can include determining an intra prediction mode of a current prediction unit; constructing a mode group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current prediction unit; determining a mode group indicator and a prediction mode index of the current prediction unit; and encoding the mode group indicator and the prediction mode index, in which the mode group indicator indicates whether or not the intra prediction mode of the current prediction unit belongs to the mode group, when the mode group indicator indicates that the intra prediction mode of the current prediction unit belongs to the mode group, the prediction mode index specifies the intra prediction mode of the current prediction unit in the mode group, when the mode group indicator indicates that the intra prediction mode of the current prediction unit does not belong to the mode group, the prediction mode index specifies the intra prediction mode of the current pre

Abstract: A reconstructed block creating method in a decoder can include obtaining an intra prediction mode group indicator and a prediction mode index from a received bitstream; decoding an intra prediction mode using the intra prediction mode group indicator, the prediction mode index and a MPM group, in which the MPM group is generated using intra prediction modes of left and top blocks of a current block, and the MPM group includes three intra prediction modes; constructing a prediction block using the intra prediction mode and reference pixels; inversely quantizing a received residual signal using a quantization parameter to create a quantized block and inversely transforming the quantized block to create a residual block; and adding the prediction block and the residual block to create a reconstructed block.

Abstract: A reconstructed block creating method in a decoder can include obtaining an intra prediction mode group indicator and a prediction mode index from a received bitstream; decoding an intra prediction mode using the intra prediction mode group indicator, the prediction mode index and a MPM group, in which the MPM group is generated using intra prediction modes of left and top blocks of a current block, and the MPM group includes three intra prediction modes; constructing a prediction block using the intra prediction mode and reference pixels; inversely quantizing a received residual signal using a quantization parameter to create a quantized block and inversely transforming the quantized block to create a residual block; and adding the prediction block and the residual block to create a reconstructed block.

Abstract: A method for decoding image, includes generating a residual block; reconstructing an intra prediction mode group indicator and a prediction mode index of a current block, wherein the indicator indicates whether the intra prediction mode of the current block belongs to which intra prediction mode group among a first or second group, and the prediction mode index specifies intra prediction mode in an intra prediction mode group indicated by the indicator; constructing the first group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current block; determining the intra prediction mode corresponding to the prediction mode index in the first group as the intra prediction mode of the current block when the indicator indicates the first group; generating a prediction block based on the determined intra prediction mode of the current block; generating a reconstructed block using the residual block and the prediction block; and performing deblocking filtering on a

Abstract: An image encoding method can include determining an intra prediction mode of a current prediction unit; constructing a mode group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current prediction unit; determining a mode group indicator and a prediction mode index of the current prediction unit; and encoding the mode group indicator and the prediction mode index, in which the mode group indicator indicates whether or not the intra prediction mode of the current prediction unit belongs to the mode group, when the mode group indicator indicates that the intra prediction mode of the current prediction unit belongs to the mode group, the prediction mode index specifies the intra prediction mode of the current prediction unit in the mode group, when the mode group indicator indicates that the intra prediction mode of the current prediction unit does not belong to the mode group, the prediction mode index specifies the intra prediction mode of the current pre

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: 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: 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: 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 for decoding image, includes generating a residual block; reconstructing an intra prediction mode group indicator and a prediction mode index of a current block, wherein the indicator indicates whether the intra prediction mode of the current block belongs to which intra prediction mode group among a first or second group, and the prediction mode index specifies intra prediction mode in an intra prediction mode group indicated by the indicator; constructing the first group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current block; determining the intra prediction mode corresponding to the prediction mode index in the first group as the intra prediction mode of the current block when the indicator indicates the first group; generating a prediction block based on the determined intra prediction mode of the current block; generating a reconstructed block using the residual block and the prediction block; and performing deblocking filtering on a

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 present 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 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 does not indicate the MPM group, in which a DC mode and a planar mode are two non-directional intra prediction mode, and a mode number of the planar mode is lower than mode numbers of the other intra prediction modes.

Abstract: A method of image decoding can include generating a quantization block by inversely scanning quantization coefficient information; generating a transform block by inversely quantizing the quantization block using a quantization step size; generating a residual block by inversely transforming the transform block; reconstructing an intra prediction mode group indicator and a prediction mode index of a current block; constructing a first group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current block; determining the intra prediction mode corresponding to the prediction mode index in the first group as the intra prediction mode of the current block when the intra prediction mode group indicator indicates the first group; generating a prediction block on the basis of the determined intra prediction mode of the current block; and generating a reconstructed block using the residual block and the prediction block.

Abstract: A method of image decoding can include generating a quantization block by inversely scanning quantization coefficient information; generating a transform block by inversely quantizing the quantization block using a quantization step size; generating a residual block by inversely transforming the transform block; reconstructing an intra prediction mode group indicator and a prediction mode index of a current block; constructing a first group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current block; determining the intra prediction mode corresponding to the prediction mode index in the first group as the intra prediction mode of the current block when the intra prediction mode group indicator indicates the first group; generating a prediction block on the basis of the determined intra prediction mode of the current block; and generating a reconstructed block using the residual block and the prediction block.

Abstract: A reconstructed block creating method is provided which includes decoding an intra prediction mode using an intra prediction mode group indicator and a prediction mode index, constructing a prediction block, inversely quantizing a received residual signal using a quantization parameter and adaptively inversely transforming the residual signal using the intra prediction mode to create a residual block, and adding the prediction block and the residual block to create a reconstructed block. The quantization parameter is reconstructed using a minimum quantization CU size, and the minimum quantization CU size is determined by a parameter transmitted from a picture parameter set. 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.

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 present 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 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 does not indicate the MPM group, in which a DC mode and a planar mode are two non-directional intra prediction mode, and a mode number of the planar mode is lower than mode numbers of the other intra prediction modes.

Abstract: A method for decoding an image is discussed. The method can include generating a residual block; reconstructing an intra prediction mode group indicator and a prediction mode index of a prediction unit; constructing a first group including three intra prediction modes using available intra prediction modes of left and top blocks of the prediction unit; determining the intra prediction mode corresponding to the prediction mode index in the first group as the intra prediction mode of the prediction unit when the intra prediction mode group indicator indicates the first group; generating a prediction block on the basis of the determined intra prediction mode of the prediction unit; generating a reconstructed block using the residual block and the prediction block; and performing deblocking filtering on a reconstructed picture.

Abstract: A method for encoding an intra prediction mode according to the present invention selects an intra prediction mode for a current block, determines the number of valid MPM candidates by checking the validity of MPM candidates of the current block, and if the number of valid MPM candidates is less than a previously set number, adds additional intra prediction modes as MPM candidates. MPM candidates can be adaptively added on the basis of the directionality of valid MPM candidates. Additionally, during the encoding of residual intra prediction modes, residual intra prediction modes are realigned on the basis of the directionality of valid MPM candidates. Accordingly, the present invention allows the information for encoding the intra prediction mode of the current block to be minimized by adding MPM candidates or realigning the residual intra prediction modes on the basis of the directionality of valid MPM candidates.

Abstract: An image decoding device is provided which reconstructs an intra prediction mode of a current prediction unit using a prediction mode group indicator and a prediction mode index, determines a size of a sub block when intra prediction is performed on each sub block of the current prediction unit, and creates reference pixels and a prediction block per sub block. Therefore, by causing the first group to include modes having a high possibility of being equal to the prediction mode of the current block and determining the intra prediction mode group indicator and the prediction mode index, it is possible to reduce an amount of information of the intra prediction mode to be encoded. Also, by creating a prediction block very similar to the current block, the number of bits to be encoded and to be decoded are reduced.

Abstract: A method for encoding an intra prediction mode according to the present invention selects an intra prediction mode for a current block, determines the number of valid MPM candidates by checking the validity of MPM candidates of the current block, and if the number of valid MPM candidates is less than a previously set number, adds additional intra prediction modes as MPM candidates. MPM candidates can be adaptively added on the basis of the directionality of valid MPM candidates. Additionally, during the encoding of residual intra prediction modes, residual intra prediction modes are realigned on the basis of the directionality of valid MPM candidates. Accordingly, the present invention allows the information for encoding the intra prediction mode of the current block to be minimized by adding MPM candidates or realigning the residual intra prediction modes on the basis of the directionality of valid MPM candidates.

Abstract: A method for decoding an image is discussed. The method can include generating a residual block; reconstructing an intra prediction mode group indicator and a prediction mode index of a prediction unit; constructing a first group including three intra prediction modes using available intra prediction modes of left and top blocks of the prediction unit; determining the intra prediction mode corresponding to the prediction mode index in the first group as the intra prediction mode of the prediction unit when the intra prediction mode group indicator indicates the first group; generating a prediction block on the basis of the determined intra prediction mode of the prediction unit; generating a reconstructed block using the residual block and the prediction block; and performing deblocking filtering on a reconstructed picture.