Method and device for intra prediction video

An apparatus for decoding a video, the apparatus comprising:

• one or more processors:
• and
• a memory storing a program which causes the one or more processors to:
• determine availability of a predetermined number of adjacent pixels used for intra prediction of a current block;
• when a first adjacent pixel among the predetermined number of adjacent pixels is unavailable, obtain a second adjacent pixel that is available by searching for the predetermined number of adjacent pixels in a predetermined direction based on the first adjacent pixel, and replace a pixel value of the first adjacent pixel with a pixel value of the second adjacent pixel;
• and
• perform intra prediction on the current block by using the predetermined number of adjacent pixels including the replaced first adjacent pixel,
• wherein the one or more processors determine an available adjacent pixel initially found to be the second adjacent pixel by searching for the predetermined number of adjacent pixels in the predetermined direction based on the first adjacent pixel, search for the second adjacent pixel by searching left and lower left adjacent pixels of the current block from bottom to top based on the first adjacent pixel, and when the second adjacent pixel is not found in the left and lower left adjacent pixels of the current block, search top and upper right adjacent pixels of the current block from left to right, and the first adjacent pixel is a lowermost left adjacent pixel from among left and lower left adjacent pixels of the current block.