Image encoding method and apparatus, and image decoding method and apparatus

An image decoding method comprising:

• obtaining, from a bitstream, information about a transform coefficient of a current block;
• obtaining an intra prediction sample of a current sample in the current block based on an intra prediction mode of the current block;
• when the intra prediction mode of the current block is an angular mode with one among left prediction directions including a lower-left prediction direction, determining a first reference sample to be used in filtering, among a plurality of reference samples in an upper side of the current block based on a position of the current sample and the intra prediction mode of the current block and determining a first weight for the first reference sample based on a Y-coordinate of the position of the current sample;
• obtaining a modified intra prediction sample of the current sample based on the first reference sample to be used in filtering, the intra prediction sample of the current sample, the first weight for the first reference sample to be used in filtering, and a second weight for the intra prediction sample of the current sample;
• generating a prediction block of the current block, the prediction block including the modified intra prediction sample of the current sample;
• obtaining a residual sample of the current sample using the information about the transform coefficient of the current block;
• and
• reconstructing the current block using the modified intra prediction sample of the current sample and the residual sample of the current sample,
• wherein based on the intra prediction mode of the current block being a first angular mode, the first reference sample to be used in filtering is determined among the plurality of reference samples in the upper side of the current block based on the position of the current sample and the first angular mode, and the first weight for the first reference sample to be used in filtering is determined based on the Y-coordinate of the position of the current sample,
• wherein based on the intra prediction mode of the current block being a second angular mode, the first reference sample to be used in filtering is determined among a plurality of reference samples in a left side of the current block based on the position of the current sample and the second angular mode, and the first weight for the first reference sample to be used in filtering is determined based on a X-coordinate of the position of the current sample, and
• wherein the obtaining of the intra prediction sample of the current sample in the current block based on the intra prediction mode of the current block comprises:
• determining a second reference sample corresponding to the current sample based on the position of the current sample and the intra prediction mode of the current block;
• and
• obtaining the intra prediction sample of the current sample based on the second reference sample.