Abrégé

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.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale

Abrégé

A method for decoding an intra prediction mode according to the present invention comprises: restoring an intra prediction mode group indicator and a prediction mode index; creating an MPM group comprising three intra prediction modes using valid intra prediction modes of blocks left and above the current block; and selecting, as the intra prediction mode of the current block, an intra prediction mode from within the group corresponding to the prediction mode indicator and the prediction mode index, wherein the non-directional intra prediction modes have smaller intra prediction mode numbers than the directional intra prediction modes. Therefore, the encoding efficiency of the intra prediction mode can be improved by using modes having a high probability of being identical to the intra prediction mode of the current block on the basis of the valid intra prediction modes of blocks left and above the current block. Additionally, the amount of information needed to encode the intra prediction mode of the current block can be reduced by configuring the method so that the non-directional modes are assigned indices having low occurrence frequencies.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale

Abrégé

An image decoding apparatus according to the present invention comprises: an intra prediction unit for generating a prediction block by reconstructing the intra prediction mode of the current block, in current block or sub-block of the current block units; a reverse scanning unit for transforming residual signals into a two-dimensional quantization block; a reverse quantization unit for reverse quantizing the quantization block using a quantization parameter; and a reverse transformation unit for reverse transforming the reverse quantization block. The quantization parameter predictor, used to reconstruct the quantization parameter, is generated by using the quantization parameters of the coding units left and above the current coding unit (CU). Therefore, the image quality is improved by adaptively controlling the quantization parameters on the basis of the encoding size, and the efficiency of image compression is improved by efficient encoding and decoding of the quantization parameters which reduce the number of bits necessary for transmitting quantization parameters.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale

Abrégé

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.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale

Abrégé

An image decoding method according to the present invention comprises: reconstructing an intra prediction mode group indicator and a prediction mode index of the current block; creating a first group with valid intra prediction modes of blocks left and above the current block; and, from the group indicated by the intra prediction mode group indicator, selecting a intra prediction mode corresponding to the prediction mode index as the intra prediction mode of the current block, wherein the size of a prediction block is in accordance with the information regarding the transformation size. Therefore, on the basis of the valid intra prediction modes of blocks left and above the current block, the intra prediction mode group indicator and the prediction mode index are determined by including, in the first group, the modes with high probabilities of being identical to the intra prediction mode of the current block, thereby reducing the amount of intra prediction information to be encoded.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale

Abrégé

A method for generating a reconstructed block according to the present invention comprises: decoding an intra prediction mode using a received intra prediction mode group indicator and a prediction mode index; generating a prediction block in accordance with the intra prediction mode; reverse quantizing a received residual signal using a quantization parameter; generating a residual block through an adaptive reverse transformation on the basis of the intra prediction mode; and generating a reconstructed block by adding the prediction block and the residual block, wherein the quantization parameter is reconstructed in accordance with the received information indicating the minimum quantized CU size, and the minimum quantized CU size information is determined in accordance with a parameter transmitted from a picture parameter set. Therefore, the image quality is improved by adaptively controlling the quantization parameters on the basis of the encoding size, and the efficiency of image compression is improved by efficient encoding and decoding of the quantization parameters which reduce the number of bits necessary for transmitting quantization parameters.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale

Abrégé

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.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale

Abrégé

An image decoding apparatus according to the present invention reconstructs the intra prediction mode of a current prediction unit by using a prediction mode group indicator and a prediction mode index, determines the size of a sub-block if the current prediction unit generates the intra prediction blocks in a plurality of sub-block units, and generates reference pixels and prediction blocks for each sub-block. Therefore, the amount of information for the intra prediction mode to be encoded can be reduced by selecting the group indicator and the prediction mode index, which are to be encoded for the current block, using modes having a high likelihood of being identical to the intra prediction mode of the current block, on the basis of the valid intra prediction modes of blocks on the left and above the current block. Additionally, encoding and decoding efficiencies are raised by generating a prediction block that is similar to the current block, thus reducing the number of bits of the residual block to be encoded and decoded.

Classes IPC  ?

• H04N 7/34 - utilisant la prédiction spatiale