Image data encoding/decoding method and apparatus

Abstract

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.

What is claimed is: 
     
         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.