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. An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
receiving a bitstream including a current image;
dividing, based on coding information from the bitstream, a coding block in the current image to obtain one or more sub-blocks,
wherein the coding information includes at least one of a first flag indicating whether to divide the coding block to obtain the one or more sub-blocks, a second flag indicating whether to divide the coding block asymmetrically, or a third flag indicating whether a division direction for the coding block is a horizontal direction or a vertical direction, and
wherein, in case the coding block is divided asymmetrically, a first sub-block having a ¼ size of the coding block is obtained, the first sub-block belonging to the one or more sub-blocks ¾; and
obtaining a residual signal of the coding block by performing inverse-quantization and inverse-transformation on the first sub-block.
2. An image encoding method performed by an image encoding apparatus, the image encoding method comprising:
dividing a coding block in a current image to obtain one or more sub-blocks, coding information on the dividing the coding block being encoded into a bitstream,
wherein the coding information includes at least one of a first flag indicating whether to divide the coding block to obtain the one or more sub-blocks, a second flag indicating whether to divide the coding block asymmetrically, or a third flag indicating whether a division direction for the coding block is a horizontal direction or a vertical direction,
wherein, in case the coding block is divided asymmetrically, a first sub-block having a ¼ size of the coding block is obtained, the first-sub-block belonging to the one or more sub-blocks; and
encoding a residual signal of the coding block by performing a transform on the first-sub-block.
3. A non-transitory computer-readable recording medium storing a bitstream that is generated by an image encoding method, the image encoding method comprising:
dividing a coding block in a current image to obtain one or more sub-blocks, coding information on the dividing the coding block being encoded into the bitstream,
wherein the coding information includes at least one of a first flag indicating whether to divide the coding block to obtain the one or more sub-blocks, a second flag indicating whether to divide the coding block asymmetrically, or a third flag indicating whether a division direction for the coding block is a horizontal direction or a vertical direction,
wherein, in case the coding block is divided asymmetrically, a first sub-block having a ¼ size of the coding block is obtained, the first-sub-block belonging to the one or more sub-blocks; and
encoding a residual signal of the coding block by performing a transform on the first-sub-block.
4. A method of transmitting a bitstream that is generated by an image encoding method, the image encoding method comprising:
dividing a coding block in a current image to obtain one or more sub-blocks, coding information on the dividing the coding block being encoded into the bitstream,
wherein the coding information includes at least one of a first flag indicating whether to divide the coding block to obtain the one or more sub-blocks, a second flag indicating whether to divide the coding block asymmetrically, or a third flag indicating whether a division direction for the coding block is a horizontal direction or a vertical direction,
wherein, in case the coding block is divided asymmetrically, a first sub-block having a ¼ size of the coding block is obtained, the first-sub-block belonging to the one or more sub-blocks; and
encoding a residual signal of the coding block by performing a transform on the first-sub-block.