Image encoding/decoding method and apparatus, and recording medium for storing bitstream that involves performing intra prediction using constructed reference sample

A method of encoding an image, the method comprising:

• deriving an intra prediction mode for a current block;
• deriving a reference sample for the current block;
• and
• performing intra prediction on the current block by using the derived reference sample,
• wherein the reference sample is included in a reference sample line,
• wherein the reference sample line is derived by selecting one reference sample line among a plurality of neighboring reference sample lines of the current block based on a position of the current block within a coding tree block,
• wherein when an upper boundary of the current block, partitioned from the coding tree block, corresponds to an upper boundary of the coding tree block, the reference sample line is derived by selecting a reference sample line closest to the current block,
• wherein the reference sample is derived by performing filtering samples of the selected reference sample line only when the selected reference sample line is the reference sample line closest to the current block among the plurality of neighboring reference sample lines, and
• wherein the filtering is performed only using the reference sample of the reference sample line closest to the current block.

A non-transitory storage medium storing a bitstream generated by a method of encoding an image, the method including:

• deriving an intra prediction mode for a current block;
• deriving a reference sample for the current block;
• and
• performing intra prediction on the current block by using the derived reference sample,
• wherein the reference sample is included in a reference sample line,
• wherein the reference sample line is derived by selecting one reference sample line among a plurality of neighboring reference sample lines of the current block based on a position of the current block within a coding tree block,
• wherein when an upper boundary of the current block, partitioned from the coding tree block, corresponds to an upper boundary of the coding tree block, the reference sample line is derived by selecting a reference sample line closest to the current block,
• wherein the reference sample is derived by performing filtering samples of the selected reference sample line only when the selected reference sample line is the reference sample line closest to the current block among the plurality of neighboring reference sample lines, and
• wherein the filtering is performed only using the reference sample of the reference sample line closest to the current block.