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.

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.

Abstract: A method of inversely quantizing a quantized block is discussed. The method according to an embodiment includes restoring a differential quantization parameter, generating a quantization parameter predictor, generating a quantization parameter using the differential quantization parameter and the quantization parameter predictor, and inversely quantizing the quantized block using the quantization parameter and a quantization matrix.

Abstract: A method of post-processing a reconstructed image is discussed. The method according to an embodiment includes determining that a deblocking filtering process is performed per slice; when it is determined that the deblocking filtering process is performed, applying the deblocking filtering process to the slice; and applying an edge offset if a sample adaptive offset (SAO) type indicates an edge offset.

Abstract: Provided is a method of post-processing a reconstructed image. The method according to an embodiment includes determining a boundary strength for each 4-sample edge which is a prediction edge or a transform edge and lies on 8×8 sample grid, determining whether deblocking filtering is applied on the 4-sample edge or not using the boundary strength and a boundary quantization parameter, filtering the 4-sample edge if the deblocking filtering is applied on the 4-sample edge, and applying an edge offset if a sample adaptive offset (SAO) type indicates an edge offset.

Abstract: An apparatus of post-processing a reconstructed image is discussed. The apparatus according to an embodiment includes a deblocking filter for determining a boundary strength for each 4-sample edge which is a prediction edge or a transform edge and lies on 8×8 sample grid, determining whether deblocking filtering is applied on the 4-sample edge or not using the boundary strength and a boundary quantization parameter, and filtering the 4-sample edge if the deblocking filtering is applied on the 4-sample edge; and a sample adaptive offset adder for, if a sample adaptive offset type indicates an edge offset, generating an edge index of a current sample, generating an edge offset corresponding to the edge index to the current sample, and adding the edge offset to the current sample.

Abstract: An apparatus of post-processing a reconstructed image is discussed. The apparatus according to an embodiment includes a deblocking filter for determining a boundary strength for each 4-sample edge which is a prediction edge or a transform edge and lies on 8×8 sample grid, determining whether deblocking filtering is applied on the 4-sample edge or not using the boundary strength and a boundary quantization parameter, and filtering the 4-sample edge if the deblocking filtering is applied on the 4-sample edge; and a sample adaptive offset adder for, if a sample adaptive offset type indicates an edge offset, generating an edge index of a current sample, generating an edge offset corresponding to the edge index to the current sample, and adding the edge offset to the current sample.

Abstract: An intra prediction mode decoding method includes 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 the intra prediction mode corresponding to the prediction mode index in the intra prediction group corresponding to the intra prediction mode group indicator, and assigning the lowest mode numbers to non-directional modes. Therefore, it is possible to reduce the amount of information for encoding the intra prediction mode of the current block by using intra prediction modes having higher possibility of being equal to the intra prediction mode of the current block. Also, it is possible to reduce the amount of information by assigning lowest mode numbers to the non-directional modes.

Abstract: An intra prediction mode decoding method includes 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 the intra prediction mode corresponding to the prediction mode index in the intra prediction group corresponding to the intra prediction mode group indicator, and assigning the lowest mode numbers to non-directional modes. Therefore, it is possible to reduce the amount of information for encoding the intra prediction mode of the current block by using intra prediction modes having higher possibility of being equal to the intra prediction mode of the current block. Also, it is possible to reduce the amount of information by assigning lowest mode numbers to the non-directional modes.

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: Provided is a method generates an edge index of a current sample, and applies an edge offset corresponding to the edge index to the current sample. The edge index is generated using the differences between a current sample and two neighboring samples determined by an edge offset type. Accordingly, the difference between original samples and reconstructed samples are effectively reduced by generating the optimum edge index. Also, the quantity of bits required for reducing the differences are reduced by fixing the sign of offset to positive or negative.

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: 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 minimizes the information for encoding the intra prediction mode of the current block by adding MPM candidates or realigning the residual intra prediction modes on the basis of the directionality of valid MPM candidates.

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 intra prediction mode decoding method includes 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 the intra prediction mode corresponding to the prediction mode index in the intra prediction group corresponding to the intra prediction mode group indicator, and assigning the lowest mode numbers to non-directional modes. Therefore, it is possible to reduce the amount of information for encoding the intra prediction mode of the current block by using intra prediction modes having higher possibility of being equal to the intra prediction mode of the current block. Also, it is possible to reduce the amount of information by assigning lowest mode numbers to the non-directional modes.

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 minimizes the information for encoding the intra prediction mode of the current block 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 method is provided which includes reconstructing an intra prediction mode group indicator and a prediction mode index of a current block, constructing a first group using valid intra prediction modes of left and top blocks, and determining the intra prediction mode corresponding to the prediction mode index and the intra prediction mode group indicator. Therefore, by causing the first group to include modes having a high possibility of being equal to the prediction mode of the current block on the basis of the valid intra prediction modes of the left and top blocks of the current block and determining the intra prediction mode group indicator and the prediction mode index to be encoded using the first group, it is possible to reduce an amount of information of the intra prediction mode to be encoded.

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 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 minimizes the information for encoding the intra prediction mode of the current block by adding MPM candidates or realigning the residual intra prediction modes on the basis of the directionality of valid MPM candidates.

Abstract: An intra prediction mode decoding method includes 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 the intra prediction mode corresponding to the prediction mode index in the intra prediction group corresponding to the intra prediction mode group indicator, and assigning the lowest mode numbers to non-directional modes. Therefore, it is possible to reduce the amount of information for encoding the intra prediction mode of the current block by using intra prediction modes having higher possibility of being equal to the intra prediction mode of the current block. Also, it is possible to reduce the amount of information by assigning lowest mode numbers to the non-directional modes.