An intra prediction method performed by a decoding apparatus, the method comprising: deriving a first candidate intra prediction mode based on a left neighboring block of a current block, wherein when the left neighboring block is located outside of a current picture, the first candidate intra prediction mode is set equal to intra DC mode, wherein when the left neighboring block is not located in a current slice in which the current block is located, the first candidate intra prediction mode is set equal to the intra DC mode, wherein when the left neighboring block is not an intra coded block, the first candidate intra prediction mode is set equal to the intra DC mode; deriving a second candidate intra prediction mode based on an upper neighboring block of the current block, wherein when the upper neighboring block is located outside of the current picture, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not located in the current slice, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not located in a current largest coding unit in which the current block is located, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not an intra coded block, the second candidate intra prediction mode is set equal to the intra DC mode; determining an intra prediction mode for the current block as one of candidate modes including the first candidate intra prediction mode and the second candidate intra prediction mode; and generating prediction samples on the current block based on the determined intra prediction mode. deriving a first candidate intra prediction mode based on a left neighboring block of a current block, wherein when the left neighboring block is located outside of a current picture, the first candidate intra prediction mode is set equal to intra DC mode, wherein when the left neighboring block is not located in a current slice in which the current block is located, the first candidate intra prediction mode is set equal to the intra DC mode, wherein when the left neighboring block is not an intra coded block, the first candidate intra prediction mode is set equal to the intra DC mode; wherein when the left neighboring block is located outside of a current picture, the first candidate intra prediction mode is set equal to intra DC mode, wherein when the left neighboring block is not located in a current slice in which the current block is located, the first candidate intra prediction mode is set equal to the intra DC mode, wherein when the left neighboring block is not an intra coded block, the first candidate intra prediction mode is set equal to the intra DC mode; deriving a second candidate intra prediction mode based on an upper neighboring block of the current block, wherein when the upper neighboring block is located outside of the current picture, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not located in the current slice, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not located in a current largest coding unit in which the current block is located, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not an intra coded block, the second candidate intra prediction mode is set equal to the intra DC mode; wherein when the upper neighboring block is located outside of the current picture, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not located in the current slice, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not located in a current largest coding unit in which the current block is located, the second candidate intra prediction mode is set equal to the intra DC mode, wherein when the upper neighboring block is not an intra coded block, the second candidate intra prediction mode is set equal to the intra DC mode; determining an intra prediction mode for the current block as one of candidate modes including the first candidate intra prediction mode and the second candidate intra prediction mode; and generating prediction samples on the current block based on the determined intra prediction mode.