Method and apparatus for block-based depth map coding and 3D video coding method using the same

1. A method for decoding a depth map, the method comprising:

performing bitplane decoding on a bitstream in units of blocks of a predetermined size to reconstruct the depth map;

decoding coding mode information for each depth map block, the coding mode information being contained in the bitstream; and

decoding XOR operation information for each bitplane block contained in the bitstream,

wherein the bitplane decoding is performed in response to the decoded coding mode information indicating bitplane decoding,

wherein the bitplane decoding comprises adaptively performing XOR operation in units of bitplane blocks; and

the XOR operation is performed on a bitplane block only in response to the decoded XOR operation information indicating that an XOR operation has to be performed.

2. The method of claim 1 , further comprising reconstructing the depth map by combining bitplane blocks subjected to XOR operation and/or bitplane blocks not subjected to XOR operation.

3. A method for decoding a depth map, the method comprising:

decoding XOR operation information for each bitplane block contained in the bitstream; and

performing XOR operation information using a restored bitplane block and a reference bitplane block;

restoring coding mode information for each depth map block, the coding mode information contained in the bitstream, the method being performed when the decoding mode information indicates bitplane coding

wherein the XOR operation on the restored bitplane block and the reference bitplane block is performed on a bitplane block only in response to the decoded XOR operation information indicating that XOR operation has to be performed, and

wherein the performing of the SOR operation using the bitplane block and the reference bitplane block comprises:

decoding a bitstream in units of bitplane to restore a bitplane block;

adaptively performing XOR operation on the restored bitplane block; and

combining bitplane blocks subjected to XOR operation and/or bitplane blocks not subjected to XOR operation.

4. The method of claim 3 , further comprising:

restoring block mode information contained in the bitstream,

wherein, in the decoding of the bitstream, the bitplane block is restored according to a method indicated by the block mode information.

5. The method of claim 4 , wherein, if an image to be decoded is an intra picture, the block mode information indicates one mode among an “all — 0 mode,” an “all — 1 mode,” and a “binary image compression mode.”

6. The method of claim 4 , wherein, in response to the block mode information indicating the “all — 0 mode” or the “all — 1 mode,” pixel values of the restored bitplane block are all “0” or “1,” respectively.

7. The method of claim 4 , wherein, if the block mode information indicates the “binary image compression mode,” the bitplane block is restored according to a decoding method regarding the binary image compression mode.

8. The method of claim 7 , wherein the binary image compression mode refers to a Context-based Arithmetic Encoding (CAE) method.

9. The method of claim 7 , wherein the binary image compression mode refers to one selected from a group including a combination of Run Length coding (RLC) and Variable Length Coding (VLC), Context-based Adaptive Binary Arithmatic Coding (CABAC), a Joint Bi-level Image Processing Group (JBIG) method, and a Quad Tree method.

10. The method of claim 4 , wherein, if an image to be decoded is an inter picture, the block mode information indicates one mode among a “No Update Without MV mode”, an “all — 0 mode,” an “all — 1 mode,” a “No Update with MV mode,” and a “binary image compression mode.”

11. The method of claim 10 , wherein, if the block mode information indicates the “No Update Without MV mode” or the “No Update with MV mode,” in the decoding of the bitstream, the bitplane block is restored through motion prediction using an predicted value of a motion vector or a decoded motion vector.

12. The method of claim 3 , wherein the reference bitplane block is a restored bitplane block for a bit level that is 1 level higher than that of the bitplane block or for a specific level of bit selected from among other bitplanes except the bitplane block.

13. The method of claim 3 , wherein, in the combining of the bitplane blocks, if n (≦N) bitplane blocks are combined, further comprising adding (N−n) bits as lower-level bits to each pixel value of the combined bitplane block of the n bitplane blocks, thereby reconstructing the depth map block that is represented by N bits.

14. A depth map decoding method, comprising:

decoding coding mode information for each depth map block, the coding mode information contained in a bitstream; and

performing bitplane decoding or Discrete Cosine Transform (DCT)-based decoding on the bitstream in units of blocks according to the decoded coding mode information to restore bitplane blocks,

wherein the performing of bitplane decoding comprises:

decoding the bitstream in units of bitplane to restore a bitplane block;

decoding XOR operation information for each bitplane block contained in the bitstream;

adaptively performing XOR operation on the restored bitplane block; and

combining bitplane blocks subjected to XOR operation and/or bitplane blocks not subjected to XOR operation, and

wherein the XOR operation is performed on a bitplane block only in response to the decoded XOR operation information indicating that XOR operation has to be performed.

15. The depth map decoding method of claim 14 , wherein the DCT-based decoding is one decoding method among MPEG-1, MPEG-2, MPEG-4 Part 2 Visual, H.264/AVC (Advanced Video Coding), and VC (Video Coding)-1.

16. The depth map decoding method of claim 14 , wherein the coding mode information indicates one selected between the bitplane coding and the DCT-based coding through evaluation in coding efficiency based on a predetermined algorithm when the depth map is encoded in units of blocks.

17. The depth map decoding method of claim 16 , wherein the predetermined algorithm is a Rate-Distortion (RD) optimization technique.

18. A method for decoding a depth map block each pixel of which is represented by N bits, the method comprising:

performing decoding according to block mode information for each bitplane block to restore n (≦N) bitplane blocks;

adaptively performing XOR operation on each of the n bitplane blocks using a reference bitplane block according to XOR operation information for each of the bitplane blocks; and

combining the n bitplane blocks subjected to and not subjected to the XOR operation,

wherein if n is less than N, the method further comprises adding (N−n) bits as lower-level bits to each pixel value of the combined bitplane block of the n bitplane blocks, thereby reconstructing the depth map block that is represented by N bits, and

wherein the XOR operation is performed on a bitplane block only in response to the decoded XOR operation information indicating that XOR operation has to be performed.

19. The depth map decoding method of claim 18 , wherein the block mode information indicates one mode among an “all — 0 mode,” an “all — 1 mode,” and a “binary image compression mode.”

20. The depth map decoding method of claim 18 , wherein the block mode information indicates one mode among a “No Update Without MV mode,” an “all — 0 mode,” an “all — 1 mode,” a “No Update with MV mode,” and a “binary image compression mode.”

21. The depth map decoding method of claim 20 , wherein the binary image compression mode refers to a Context-based Arithmetic Encoding (CAE) method.

22. The depth map decoding method of claim 21 , wherein a reference bitplane block required to perform the CAE method is generated using bitplane blocks that are obtained by adaptively performing XOR operation on bitplane blocks for a bit level having the same bit level as that of a current bitplane block, among M bitplane blocks generated by dividing each of reference depth map blocks adjacent to the current depth map block.

23. The depth map decoding method of claim 22 , wherein, in the generating of the reference bitplane block, the XOR operation is performed when XOR operation information of the current bitplane block indicates that the current bitplane block has been subjected to XOR operation.

24. The depth map decoding method of claim 22 , wherein each reference depth map block is a depth map block reconstructed in the reconstructing of the depth map block or a depth map block reconstructed using Discrete Cosine Transform (DCT)-based decoding.

25. The depth map decoding method of claim 18 , wherein the decoding is performed by a binary image compression mode that is one selected from a group including a combination of Run Length coding (RLC) and Variable Length Coding (VLC), Context-based Adaptive Binary Arithmatic Coding (CABAC), a Joint Bi-level Image Processing Group (JBIG) method, and a Quad Tree method.

26. The depth map decoding method of claim 18 , wherein the reference bitplane block is a reconstructed bitplane block for a bit level that is 1 level higher than that of the bitplane block or for a specific level of bit selected from among other bitplanes except the bitplane block.