Method and device for encoding/decoding image, and recording medium in which bitstream is stored

An image encoding method performed by an image encoding apparatus, the method comprising:

• deriving a prediction mode of a current block;
• deriving reference samples neighboring the current block;
• deriving prediction samples of the current block based on the prediction mode of the current block and the reference samples;
• generating residual samples of the current block based on the prediction samples;
• and
• encoding image information including prediction mode information for the current block,
• wherein the reference samples include top reference samples of the current block and left reference samples of the current block,
• wherein whether a filtering is applied to the reference samples is determined based on the prediction mode of the current block and a size of the current block,
• wherein, for the filtering for the reference samples, a 3-tap filter or a 5-tap filter is used based on the size of the current block,
• wherein based on the prediction mode being a directional mode, a 4-tap interpolation filter is used for deriving the prediction samples,
• wherein based on a case that the filtering is applied to the reference samples, the filtering for the reference samples is performed based on neighboring samples of a reference sample, and
• wherein the neighboring samples of the reference sample include a first sample adjacent to the reference sample in a horizontal direction and a second sample adjacent to the reference sample in a vertical direction.

A transmission method for image data, the method comprising:

• obtaining a bitstream for the image data, wherein the bitstream is generated based on deriving a prediction mode of a current block, deriving reference samples neighboring the current block, deriving prediction samples of the current block based on the prediction mode of the current block and the reference samples, generating residual samples of the current block based on the prediction samples, and encoding image information including prediction mode information for the current block;
• and
• transmitting the image data comprising the bitstream,
• wherein the reference samples include top reference sample of the current block and left reference samples of the current block,
• wherein whether a filtering is applied to the reference samples is determined based on the prediction mode of the current block and a size of the current block,
• wherein, for the filtering for the reference samples, a 3-tap filter or a 5-tap filter is used based on the size of the current block,
• wherein based on the prediction mode being a directional mode, a 4-tap interpolation filter is used for deriving the prediction samples,
• wherein based on a case that the filtering is applied to the reference samples, the filtering for the reference samples is performed based on neighboring samples of a reference sample, and
• wherein the neighboring samples of the reference sample include a first sample adjacent to the reference sample in a horizontal direction and a second sample adjacent to the reference sample in a vertical direction.