Method and apparatus for encoding video, and method and apparatus for decoding video
A method of decoding an image including: obtaining information about an intra prediction mode applied to a current block to be decoded, from a bitstream; obtaining one of a left neighboring pixel whose location is determined based on j*dy>>n and a up neighboring pixel whose location is determined based on i*dx>>m, where a current pixel is located on (i,j), dx, dy, m and n are integers; performing intra prediction on the current pixel using one of the left neighboring pixel and the up neighboring pixel.
1. A method of decoding an image, the method comprising:
obtaining information about an intra prediction mode of a current block to be decoded, from a bitstream, the intra prediction mode indicating a particular direction among a plurality of directions, the particular direction being indicated by one of dx number in a horizontal direction and a fixed number in a vertical direction, and dy number in the vertical direction and a fixed number in the horizontal direction;
obtaining a number of neighboring pixels located on one side among a left side of the current block and an upper side of the current block according to a position of a current pixel and the one of the dx number in the horizontal direction and the dy number in the vertical direction, where dx and dy are integers according to the particular direction;
determining one of a location of a neighboring pixel located on the left side of the current block determined based on the dy number in the vertical direction and the fixed number in the horizontal direction and a location of a neighboring pixel located on the upper side of the current block determined based on the dx number in the horizontal direction and the fixed number in the vertical direction;
when the number of neighboring pixels is 1, obtaining a prediction value of the current pixel based on the neighboring pixel; and
when the number of the neighboring pixels is 2, obtaining the prediction value of the current pixel based on a weighted average of the neighboring pixels,
wherein the dx number and the dy number are determined among {32, 26, 21, 17, 13 9, 5, 2, 0, −2, −5, −9, −13, −17, −21, −26}according to the intra prediction mode of the current block,
wherein the fixed integer number is power of 2.
wherein the image is split into a plurality of maximum coding units according to information about maximum size of a coding unit,
a maximum coding unit, of the plurality of maximum coding units, is hierarchically split into one or more coding units of depths including at least one of a current depth and a lower depth according to split information,
when the split information indicates a split for the current depth, a coding unit of the current depth is split into four coding units of the lower depth, independently from neighboring coding units, and
when the split information indicates a non-split for the current depth, one or more prediction units are obtained from the coding unit of the current depth.