IMAGE DATA ENCODING/DECODING METHOD AND APPARATUS
A method for decoding a 360-degree image includes: receiving a bitstream obtained by encoding a 360-degree image; generating a prediction image by making reference to syntax information obtained from the received bitstream; combining the generated prediction image with a residual image obtained by dequantizing and inverse-transforming the bitstream, so as to obtain a decoded image; and reconstructing the decoded image into a 360-degree image according to a projection format. Here, generating the prediction image includes: checking, from the syntax information, prediction mode accuracy for a current block to be decoded; determining whether the checked prediction mode accuracy corresponds to most probable mode (MPM) information obtained from the syntax information; and when the checked prediction mode accuracy does not correspond to the MPM information, reconfiguring the MPM information according to the prediction mode accuracy for the current block.
1 . A method of decoding a 360-degree image, the method comprising:
receiving a bitstream in which the 360-degree image is encoded;
generating a predicted image with reference to syntax information acquired from the received bitstream;
acquiring a decoded image by combining the generated predicted image with a residual image acquired by inversely quantizing and inversely transforming the bitstream; and
reconstructing the decoded image into the 360-degree image according to a projection format,
wherein the generating of the predicted image comprises:
checking, in the syntax information, prediction mode precision for a current block to be decoded;
determining whether the checked prediction mode precision corresponds to most probable mode (MPM) mode information acquired from the syntax information; and
reconstructing the MPM mode information according to the prediction mode precision for the current block when the checked prediction mode precision does not correspond to the MPM mode information.
2 . The method of claim 1 , wherein the MPM mode information indicates an intra-prediction mode for at least one block among blocks adjacent to the current block.
3 . The method of claim 2 , wherein the generating of the predicted image comprises:
performing intra-prediction according to the intra-prediction mode of the block adjacent to the current block with reference to information obtained by reconstructing the MPM mode information.
4 . The method of claim 3 , wherein the performing of the intra-prediction according to the intra-prediction mode of the block adjacent to the current block comprises:
constructing a reference pixel belonging to the adjacent block; and
generating a prediction block for the current block by performing intra-prediction using the reference pixel.
5 . The method of claim 4 , wherein at the constructing of the reference pixel, when the block adjacent to the current block is unavailable, the reference pixel of the unavailable block is constructed using a boundary pixel of another block having image correlation with the current block.