Image data encoding/decoding method and apparatus

1 . A method of decoding an image with a decoding apparatus, comprising:

receiving a bitstream in which the image is encoded;

obtaining, from the bitstream, at least one among a single index for specifying a block division type of a current block in the image, a first flag specifying whether to perform horizontal binary-division and a second flag specifying whether to perform vertical binary-division, the first flag being different from the second flag;

determining, based on at least one among the single index, the first flag and the second flag, the block division type of the current block from a candidate group pre-defined in the decoding apparatus,

wherein the single index is used to select one candidate division types among a plurality of candidate division types included in the candidate group,

wherein, when a size of the current block is within a predetermined range, the plurality of candidate division types includes a first quad-division, a second quad-division, and a binary-division,

wherein, when the size of the current block is out of the predetermined range, the plurality of candidate division types does not include the second quad-division,

wherein the first quad-division is representative of dividing, based on one horizontal line and one vertical line, one coding block into four coding blocks, the second quad-division is representative of dividing, based on three horizontal lines or three vertical lines, one coding block into four coding blocks, and the binary-division is representative of dividing one coding block into two coding blocks, and

wherein the binary-division includes the horizontal binary-division and the vertical binary-division,

wherein the vertical binary-division divides one coding block vertically into two coding blocks having a same size with each other,

dividing, based on the determined block division type, 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,

wherein the four coding blocks obtained by the second quad-division have the same size each other, and

wherein the decoding each of the sub-blocks comprises selecting a prediction method from among a plurality of prediction methods including intra prediction and inter prediction, and generating a prediction block by performing the selected prediction method.

2 . The method of claim 1 , wherein the current block is set equal to a largest coding block or is set a block resulting from dividing the largest coding block,

wherein a size of the largest coding block is variably determined based on information on the largest coding block,

wherein the information on the largest coding block is signaled from the bitstream.

3 . The method of claim 1 , wherein a number of the candidate division types available for the current block is different dependent on at least one of a size of the current block or a shape of the current block.

4 . A method of encoding an image with an encoding apparatus, comprising:

determining a block division type of a current block in the image from a candidate group pre-defined in the encoding apparatus; and

encoding each of sub-blocks resulting from dividing the current block based on the determined block division type,

wherein a single index is used to select one candidate division types among a plurality of candidate division types included in the candidate group,

wherein, when a size of the current block is within a predetermined range, the plurality of candidate division types includes a first quad-division, a second quad-division, and a binary-division,

wherein, when the size of the current block is out of the predetermined range, the plurality of candidate division types does not include the second quad-division,

wherein the first quad-division is representative of dividing, based on one horizontal line and one vertical line, one coding block into four coding blocks, the second quad-division is representative of dividing, based on three horizontal lines or three vertical lines, one coding block into four coding blocks, and the binary-division is representative of dividing one coding block into two coding blocks,

wherein the binary-division includes a horizontal binary-division and a vertical binary-division,

wherein the vertical binary-division divides one coding block vertically into two coding blocks having a same size with each other,

wherein the four coding blocks obtained by the second quad-division have the same size each other, and

wherein the encoding each of the sub-blocks comprises selecting a prediction method from among a plurality of prediction methods including intra prediction and inter prediction, and generating a prediction block by performing the selected prediction method,

encoding at least one among the single index for specifying the determined block division type of the current block, a first flag specifying whether to perform the horizontal binary-division and a second flag specifying whether to perform the vertical binary-division, the first flag being different from the second flag.

5 . A method of transmitting a bitstream comprising:

determining a block division type of a current block in the image from a candidate group pre-defined in the encoding apparatus;

encoding each of sub-blocks resulting from dividing the current block based on the determined block division type to generate the bitstream; and

transmitting the bitstream,

wherein a single index is used to select one candidate division types among a plurality of candidate division types included in the candidate group,

wherein, when a size of the current block is within a predetermined range, the plurality of candidate division types includes a first quad-division, a second quad-division, and a binary-division,

wherein, when the size of the current block is out of the predetermined range, the plurality of candidate division types does not include the second quad-division,

wherein the first quad-division is representative of dividing, based on one horizontal line and one vertical line, one coding block into four coding blocks, the second quad-division is representative of dividing, based on three horizontal lines or three vertical lines, one coding block into four coding blocks, and the binary-division is representative of dividing one coding block into two coding blocks,

wherein the binary-division includes a horizontal binary-division and a vertical binary-division,

wherein the vertical binary-division divides one coding block vertically into two coding blocks having a same size with each other,

wherein the four coding blocks obtained by the second quad-division have the same size each other, and

wherein the encoding each of the sub-blocks comprises selecting a prediction method from among a plurality of prediction methods including intra prediction and inter prediction, and generating a prediction block by performing the selected prediction method,

encoding at least one among the single index for specifying the determined block division type of the current block, a first flag specifying whether to perform the horizontal binary-division and a second flag specifying whether to perform the vertical binary-division, the first flag being different from the second flag.