Encoding / decoding method and apparatus using a tree structure
The present disclosure provides an encoding/decoding method using a tree structure. The encoding method for encoding image information includes: grouping predetermined areas having the image information into a plurality of groups, and generating a node value of each layer up to an uppermost layer by determining a minimum value or a maximum value of information to be encoded within grouped areas as information on the grouped areas; and encoding a difference value between the node value of each layer and a node value of an upper layer or a difference value between the node value of each layer and a value determined based on a preset criterion. Accordingly, the encoding efficiency and in turn the video compression efficiency are improved by using the tree structure in the encoding of various pieces of image information and the decoding of the resultant encoded data.
1. A decoding method performed by a video decoding apparatus for reconstructing image information divided by a tree structure from a bitstream, comprising:
decoding the bitstream to reconstruct additional information, including first information on a minimum block size and second information on a difference between the minimum block size and a maximum block size, wherein the maximum block size is identified based on the first information on the minimum block size and the second information on the difference; and
reconstructing a partition flag indicating whether or not each block, starting from a block corresponding to an uppermost layer of the tree structure, is divided into blocks of a lower layer, the block corresponding to the uppermost layer having the maximum block size identified based on the first and second information, and reconstructing image information of a block which is not further divided.
2. The decoding method of claim 1 , wherein, when the partition flag indicates that a block of an upper layer is divided into blocks of a lower layer, the block of the upper layer is divided into four equal-sized blocks.
3. The decoding method of claim 1 , wherein the partition flag indicating whether a block having the minimum block size is divided is not included in the bitstream.
4. The decoding method of claim 1 , wherein the additional information is included as a sequence information.
5. The decoding method of claim 1 , wherein the image information includes prediction information and information on residuals needed for reconstructing pixels of the block which is not further divided.
6. A decoding apparatus for reconstructing image information divided by a tree structure from a bitstream, comprising:
an additional information decoder configured to decode the bitstream to reconstruct additional information, including first information on a minimum block size and second information on a difference between the minimum block size and a maximum block size, wherein the additional information decoder identifies the maximum block size based on the first information on the minimum block size and the second information on the difference; and
a tree decoder configured to reconstruct a partition flag indicating whether or not each block, starting from a block corresponding to an uppermost layer of the tree structure, is divided into blocks of a lower layer, the block corresponding to the uppermost layer having the maximum block size identified based on the first and second information, and reconstruct image information of a block which is not further divided.
7. The decoding apparatus of claim 6 , wherein, when the partition flag indicates that a block of an upper layer is divided into blocks of a lower layer, the block of the upper layer is divided into four equal-sized blocks.
8. The decoding method of claim 6 , wherein the partition flag indicating whether a block having the minimum block size is divided is not included in the bitstream.
9. The decoding apparatus of claim 6 , wherein the additional information is included as a sequence information.
10. The decoding apparatus of claim 6 , wherein the image information includes prediction information and information on residuals needed for reconstructing pixels of the block which is not further divided.