Method and device for encoding and decoding intra-frame prediction

Abstract

A method and a device for encoding and decoding intra prediction are disclosed. An image decoding method for performing intra prediction comprises the steps of: receiving a bitstream including data on prediction modes of a current block and a block adjacent to the current block; extracting the data from the received bitstream so as to confirm the prediction mode of the adjacent block; determining whether a boundary pixel within the adjacent block can be used as a reference pixel for the current block in consideration of the prediction mode of the adjacent block; obtaining the reference pixel of the current block according to the determined result; generating a prediction block predicted in the frame on the basis of the obtained reference pixel; and decoding the current block by using the generated prediction block.

1 . An image encoding method for performing intra prediction, the method comprising:
 determining whether a boundary pixel within an adjacent block is available as a reference pixel of a current block in consideration of a prediction mode of each of the current block and the adjacent block;   obtaining the reference pixel of the current block based on a determined result;   generating a prediction block through intra prediction based on the obtained reference pixel; and   decoding the current block using the generated prediction block.   
     
     
         2 . The image encoding method of  claim 1 , wherein the determining whether the boundary pixel within the adjacent block is available as the reference pixel includes determining whether the boundary pixel is available as a reference pixel of a current picture in consideration of a reference picture of the adjacent block when the prediction mode of the adjacent block is inter prediction. 
     
     
         3 . The image encoding method of  claim 2 , wherein the reference picture is selected from a list 0 storing data for the reference picture previous to the current picture or a list 1 storing data for the reference picture subsequent to the current picture, and the current picture is included in the list 0 or the list 1. 
     
     
         4 . The image encoding method of  claim 2 , wherein the boundary pixel is determined to be available as the reference pixel of the current picture, when the reference picture of the adjacent block is the current picture. 
     
     
         5 . The image encoding method of  claim 2 , wherein the boundary pixel is determined to be unavailable as the reference pixel of the current picture, when the reference picture of the adjacent block is not the current picture. 
     
     
         6 . An image decoding method for performing intra prediction, the method comprising:
 receiving a bitstream including data on prediction modes of a current block and a block adjacent to the current block;   confirming the prediction mode of the adjacent block by extracting the data from the received bitstream;   determining whether a boundary pixel within the adjacent block is available as a reference pixel of the current block in consideration of the prediction mode of the adjacent block;   obtaining the reference pixel of the current block depending on the determined result;   generating a prediction block through intra prediction block based on the obtained reference pixel; and   decoding the current block using the generated prediction block.   
     
     
         7 . The image decoding method of  claim 6 , wherein the determining whether the boundary pixel within the adjacent block is available as the reference pixel includes determining whether the boundary pixel is available as a reference pixel of a current picture in consideration of a reference picture of the adjacent block when the prediction mode of the adjacent block is inter prediction. 
     
     
         8 . The image decoding method of  claim 7 , wherein the reference picture is selected from a list 0 storing data for the reference picture previous to the current picture or a list 1 storing data for the reference picture subsequent to the current picture, and the current picture is included in the list 0 or the list 1. 
     
     
         9 . The image decoding method of  claim 7 , wherein the boundary pixel is determined to be available as the reference pixel of the current picture, when the reference picture of the adjacent block is the current picture. 
     
     
         10 . The image encoding method of  claim 7 , wherein the pixel in the adjacent block is determined to be unavailable as the reference pixel of the current picture, when the reference picture of the adjacent block is not the current picture. 
     
     
         11 . An image encoding method for performing intra prediction, the method comprising:
 determining whether each of a left block and an upper block of a current block is available for constructing a reference pixel of the current block;   selecting a most probable mode MPM candidate group based on the determined result;   determining redundancy of prediction blocks derived from intra prediction modes in the MPM candidate group;   selecting a MPM group using a prediction mode of a substitute block adjacent to the left block or adjacent to the upper block when it is determined that the redundancy exists; and   performing an intra prediction mode encoding on the current block based on the selected MPM group.   
     
     
         12 . The image encoding method of  claim 11 , wherein the determining the redundancy includes determining the redundancy based on variance values computed for reference pixel values in two or more consecutive blocks among the blocks located at lower left, left, upper left, upper, and upper right of the current block, when the left block and the upper block are all available. 
     
     
         13 . The image encoding method of  claim 11 , wherein the determining the redundancy includes selecting intra prediction modes constructed by referring only to boundary pixels between an unavailable block and the current block when at least one of the left block and the upper block is unavailable, and determining that redundancy exists when at least two of the prediction modes selected are included in the MPM candidate group. 
     
     
         14 . The image encoding method of  claim 11 , wherein the substitute block is selected from adjacent blocks located at lower left, upper left, and upper right of the current block. 
     
     
         15 . An image decoding method for performing intra prediction, the method comprising:
 extracting data on whether a prediction mode for a current block is included in a most probable mode MPM group from a bitstream received;   determining whether the prediction mode for the current block is included in the MPM group based on the data;   extracting MPM group index data of the current block from the received bitstream when it is determined that the prediction mode for the current block is included in the MPM group;   confirming the prediction mode for the current block in the MPM group based on the extracted MPM group index data; and   performing intra prediction on the current block based on the confirmed prediction mode.   
     
     
         16 . The image decoding method of  claim 15 , wherein the MPM group is selected by determining whether each of a left block and an upper block of the current block is available for constructing a reference pixel of the current block, selecting a MPM candidate group based on a determined result, determining redundancy of prediction blocks derived from intra prediction modes in the MPM candidate group, and using a prediction mode of a substitute block adjacent to the left block or adjacent to the upper block when it is determined that the redundancy exists. 
     
     
         17 . The image decoding method of  claim 16 , wherein the determining the redundancy includes determining the redundancy based on variance values computed for reference pixel values in two or more consecutive blocks among the blocks located at lower left, left, upper left, upper, and upper right of the current block, when the left block and the upper block are all available. 
     
     
         18 . The image decoding method of  claim 16 , wherein the determining the redundancy includes selecting an intra prediction mode constructed by referring only to boundary pixels between an unavailable block and the current block when at least one of the left block and the upper block is unavailable, and determining that the redundancy exists when at least two of the prediction modes selected are included in the MPM candidate group. 
     
     
         19 . The image decoding method of  claim 16 , wherein the substitute block is selected from adjacent blocks located at lower left, upper left, and upper right of the current block. 
     
     
         20 . The image decoding method of  claim 16 , wherein the substitute block is selected with a clockwise or counterclockwise priority among adjacent blocks located at lower left, upper left, and upper right of the current block.