Method and device for processing video signal

Abstract

A method of video decoding according to the present invention may comprise determining an intra prediction mode of a current block, determining a DC value based on at least one of top reference samples or left reference samples of the current block when the intra prediction mode of the current block is a DC mode, and deriving a prediction sample of the current block based on the DC value.

1 - 15 . (canceled) 
     
     
         16 . A method of decoding a video, the method comprising:
 determining an intra prediction mode of a current block;   in response to the intra prediction mode of the current block being a directional mode, obtaining a first prediction value for a current sample in the current block based on a first reference sample, the first reference sample being adjacent to the current block and being located in a prediction direction of the directional mode from the current sample; and   generating a final prediction value of the current sample in the current block by modifying the first prediction value based on a second reference sample, the second reference sample being located in a direction opposite to the prediction direction of the directional mode from the current sample,   wherein the intra prediction mode of the current block is determined as a conventional intra prediction mode or an extended intra prediction mode,   wherein whether the intra prediction mode of the current block is determined as the extended intra prediction mode is determined based on a shape of the current block, and   wherein the first prediction value is modified in response that a size of the current block is greater than a threshold value.   
     
     
         17 . The method of  claim 16 , wherein modifying the first prediction value is allowed only when the directional mode is one of intra prediction modes pre-defined in a decoder. 
     
     
         18 . The method of  claim 17 , wherein prediction values of samples belonging to a first region in the current block are modified but prediction values of samples belonging to a second region in the current block are output as they are. 
     
     
         19 . The method of  claim 18 , wherein a size of the first region and the second region is determined differently based on the intra prediction mode of the current block. 
     
     
         20 . The method of  claim 19 , wherein a position of the second reference sample is determined based on a value resulting from adding an offset value to a x-coordinate or a y-coordinate of the current sample, and
 wherein the offset value is determined based on an angle of the directional mode.   
     
     
         21 . The method of  claim 20 , wherein the first prediction value for the current sample is obtained based on a weight sum of a plurality of first reference samples while the second prediction value is obtained by copying a value of the second reference sample. 
     
     
         22 . The method of  claim 16 , wherein in response to the shape of the current block being a non-square, the intra prediction mode of the current block is determined as the extended intra prediction mode, and
 wherein in response to the shape of the current block being a square, the intra prediction mode of the current block is determined as the non-extended intra prediction mode.   
     
     
         23 . A method of encoding a video, the method comprising:
 obtaining a first prediction value for a current sample in a current block based an intra prediction mode of the current block and a first reference sample, the intra prediction mode being representative of a directional mode, the first reference sample being adjacent to the current block and being located in a prediction direction of the directional mode from the current sample; and
 generating a final prediction value of the current sample in the current block by modifying the first prediction value based on a second reference sample, the second reference sample being located in a direction opposite to the prediction direction of the directional mode from the current sample, 
 wherein the intra prediction mode of the current block is determined as a conventional intra prediction mode or an extended intra prediction mode, 
 wherein whether the intra prediction mode of the current block is determined as the extended intra prediction mode is determined based on a shape of the current block, and 
 wherein the first prediction value is modified in response that a size of the current block is greater than a threshold value. 
   
     
     
         24 . A non-transitory computer-readable medium for storing data associated with a video signal, comprising:
 a data stream stored in the non-transitory computer-readable medium, the data stream comprising intra prediction mode information for intra prediction of a current block,   wherein an intra prediction mode of a current block is determined based on the intra prediction mode information,   wherein the intra prediction mode of the current block is determined as a conventional intra prediction mode or an extended intra prediction mode,   wherein whether the intra prediction mode of the current block is determined as the extended intra prediction mode is determined based on a shape of the current block,   wherein, in response to the intra prediction mode of the current block being a directional mode, a first prediction value for a current sample in the current block is obtained based on a first reference sample, the first reference sample being adjacent to the current block and being located in a prediction direction of the directional mode from the current sample,   wherein a final prediction value of the current sample in the current block is generated by modifying the first prediction value based on a second reference sample, the second reference sample being located in a direction opposite to the prediction direction of the directional mode from the current sample, and   wherein the first prediction value is modified in response that a size of the current block is greater than a threshold value.