Method and device for intra-prediction

Abstract

The multi sample prediction method of the present invention comprises the steps of: determining a sample group consisting of a plurality of samples inside a decoding target block; determining a representative position corresponding to the sample group, inside the decoding target block; determining a representative prediction value for the sample group, on the basis of the determined representative position; and determining the determined representative prediction value as the final prediction value for each of the plurality of samples making up the sample group. The present invention enhances efficiency in encoding/decoding and reduces complexity thereof.

1 . A multi-sample prediction method comprising:
 determining a sample group comprised of a plurality of samples in a decoding target block;   determining a representative position corresponding to the sample group in the decoding target block;   determining a representative prediction value with respect to the sample group based on the determined representative position; and   determining the determined representative prediction value as a final prediction value with respect to each of the plurality of samples constituting the sample group.   
     
     
         2 . The method of  claim 1 , further comprising:
 determining whether to apply multi-sample prediction to the decoding target block by using a coding parameter of the decoding target block,   wherein when it is determined to apply multi-sample prediction to the decoding target block, the operations that follow the sample group determining operation are sequentially performed and,   the coding parameter includes at least one of a size of the decoding target block and an intra prediction mode of the decoding target block.   
     
     
         3 . The method of  claim 1 , wherein, in the determining of a sample group,
 the size and shape of the sample group are determined according to the coding parameter of the decoding target block, and   the coding parameter includes at least one of the size of the decoding target block and the intra prediction mode of the decoding target block.   
     
     
         4 . The method of  claim 1 , wherein, in the determining of a representation position,
 one of positions of the plurality of samples constituting the sample group is selected as a representative position with respect to the sample group.   
     
     
         5 . The method of  claim 1 , wherein, in the determining of a representation position,
 a middle position between a plurality of samples constituting the sample group is determined as a representative position with respect to the sample group.   
     
     
         6 . The method of  claim 1 , wherein, in the determining of a representation position, a position of a sample existing outside the sample group in the decoding target block is determined as a representative position with respect to the sample group. 
     
     
         7 . The method of  claim 1 , wherein, the determining of a representation prediction value comprises:
 determining a reference position corresponding to the representative position based on the intra prediction mode of the decoding target block; and   determining a representative prediction value with respect to the sample group based on the reference position.   
     
     
         8 . The method of  claim 7 , wherein when the determined reference position is the same as a position of a single reference sample with respect to the decoding target block,
 a sample value of the reference sample having the same position as the reference position is determined as the representative prediction value in the determining of a representative prediction value.   
     
     
         9 . The method of  claim 7 , wherein, when the determined reference position is a position between a plurality of reference samples with respect to the decoding target block,
 a sample value of a reference sample positioned to be closest to a prediction direction of the decoding target block among the plurality of reference samples is determined as the representative prediction value in the determining of a representative prediction value.   
     
     
         10 . The method of  claim 7 , wherein when the determined reference position is a position between the plurality of reference samples with respect to the decoding target block, interpolation is performed on the sample values of the plurality of reference samples to determine the representative prediction value in the determining of a representative prediction value. 
     
     
         11 . The method of  claim 7 , wherein, when the determined reference position is a position between the plurality of reference samples with respect to the decoding target block,
 a sample average value of the plurality of reference samples is determined as the representative prediction value in the determining of a representative prediction value.   
     
     
         12 . An image decoding method comprising:
 determining a sample group comprised of a plurality of samples in a decoding target block;   determining a representative position corresponding to the sample group in the decoding target block;   determining a representative prediction value with respect to the sample group based on the determined representative position;   determining the determined representative prediction value as a final prediction value with respect to each of the plurality of samples constituting the sample group; and   generating a reconstructed image by using the final prediction value.   
     
     
         13 . The method of  claim 12 , wherein, in the determining of a sample group,
 the size and shape of the sample group are determined according to the coding parameter of the decoding target block, and   the coding parameter includes at least one of a size of the decoding target block and an intra prediction mode of the decoding target block.   
     
     
         14 . The method of  claim 12 , in the determining of a representation position,
 one of positions of the plurality of samples constituting the sample group is selected as a representative position with respect to the sample group.   
     
     
         15 . The method of  claim 12 , in the determining of a representation position,
 a middle position between a plurality of samples constituting the sample group is determined as a representative position with respect to the sample group.   
     
     
         16 . The method of  claim 12 , in the determining of a representation position,
 a position of a sample existing outside the sample group in the decoding target block is determined as a representative position with respect to the sample group.   
     
     
         17 . The method of  claim 12 , the determining of a representation prediction value comprises:
 determining a reference position corresponding to the representative position based on the intra prediction mode of the decoding target block; and   determining a representative prediction value with respect to the sample group based on the reference position.