Image data encoding/decoding method and apparatus

A method for encoding a 360-degree image, the method comprising:

• obtaining a 2-dimensional image projected from an image with a 3-dimensional projection structure and including at least one face;
• obtaining an extended 2-dimensional image including the 2-dimensional image and a predetermined extension region;
• and
• encoding data of the extended 2-dimensional image into a bitstream in which the 360-degree image is encoded based on a predicted image for the extended 2-dimensional image, the predicted image being obtained by selecting a prediction method from inter prediction and intra prediction, and by performing prediction based on the selected prediction method,
• wherein a size of the extension region to be padded is encoded based on first width information of the extension region on a left side of the face and second width information of the extension region on a right side of the face, both the first width information and the second width information being encoded into the bitstream, and
• wherein sample values of the extension region are determined differently according to a padding method selected from a plurality of padding methods.

A non-transitory computer-readable recording medium storing a bitstream that is generated by a method for encoding a 360-degree image, the method comprising:

• obtaining a 2-dimensional image projected from an image with a 3-dimensional projection structure and including at least one face;
• obtaining an extended 2-dimensional image including the 2-dimensional image and a predetermined extension region;
• and
• encoding data of the extended 2-dimensional image into a bitstream in which the 360-degree image is encoded based on a predicted image for the extended 2-dimensional image, the predicted image being obtained by selecting a prediction method from inter prediction and intra prediction, and by performing prediction based on the selected prediction method,
• wherein a size of the extension region to be padded is encoded based on first width information of the extension region on a left side of the face and second width information of the extension region on a right side of the face, both the first width information and the second width information being encoded into the bitstream, and
• wherein sample values of the extension region are determined differently according to a padding method selected from a plurality of padding methods.