Method and apparatus of encoding/decoding image data based on tree structure-based block division
Disclosed are methods and apparatuses for image data encoding/decoding. A method of decoding an image includes receiving a bitstream in which the image is encoded; obtaining index information for specifying a block division type of a current block in the image; and determining the block division type of the current block from a candidate group pre-defined in the decoding apparatus. The candidate group includes a plurality of candidate division types, including at least one of a non-division, a first quad-division, a second quad-division, a binary-division or a triple-division. The method also includes dividing the current block into a plurality of sub-blocks; and decoding each of the sub-blocks with reference to syntax information obtained from the bitstream.
1. A method for decoding a 360-degree image, the method comprising:
receiving a bitstream in which the 360-degree image is encoded, the bitstream including data of an extended 2-dimensional image, the extended 2-dimensional image including a 2-dimensional image and a predetermined extension region, and the 2-dimensional image being projected from an image with a 3-dimensional projection structure and including at least one face; and
reconstructing the extended 2-dimensional image by decoding the data of an extended 2-dimensional image,
wherein a size of the extension region is determined based on both 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 obtained from the bitstream,
wherein sample values of the extension region are determined differently according to a padding method selected from a plurality of padding methods,
wherein the extended 2-dimensional image is reconstructed based on a residual image, the residual image being generated by decoding information on the residual image included in the bitstream.
2. The method of claim 1 , wherein the padding method is selected from the plurality of padding methods based on selection information obtained from the bitstream.
3. The method of claim 1 , wherein the plurality of padding methods includes at least a first padding method which copies sample values of the face for the sample values of the extension region.
4. The method of claim 3 , wherein the first padding method horizontally copies the sample values of the face to the sample values of the extension region.
5. The method of claim 1 , wherein the plurality of padding methods includes at least a second padding method which changes sample values of the face for the sample values of the extension region.
6. 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,
wherein a size of the extension region is encoded based on both 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,
wherein sample values of the extension region are determined differently according to a padding method selected from a plurality of padding methods,
wherein the extended 2-dimensional image is encoded by encoding information on a residual image into the bitstream.
7. A method of transmitting a bitstream, 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;
encoding data of the extended 2-dimensional image into the bitstream in which a 360-degree image is encoded; and
transmitting the bitstream,
wherein a size of the extension region is encoded based on both 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,
wherein sample values of the extension region are determined differently according to a padding method selected from a plurality of padding methods,
wherein the extended 2-dimensional image is encoded by encoding information on a residual image into the bitstream.