Inter prediction method and apparatus using adjacent pixels, and image encoding/decoding method and apparatus using same
The present disclosure relates to an inter prediction method and apparatus using adjacent pixels, and a video encoding method and apparatus using the same. The inter prediction method for a predictive encoding includes: determining a current motion vector by estimating a motion of a current block; generating a reference block indicated by the current motion vector; calculating a motion compensation coefficient or an average compensation coefficient by using pixels neighboring the current block and pixels neighboring reference block; generating a changed reference block reflecting the motion compensation coefficient or the average compensation coefficient in the reference block; and determining the changed reference block as a predicted block of the current block. The present disclosure reduces a difference between an actual block and a predicted block by more accurately predicting the block to be encoded, thereby improving the compression efficiency.
1. An inter prediction method for encoding a video image, comprising:
determining a current motion vector of a current block in a current picture;
generating a reference block by interpolating pixels at a position indicated by the current motion vector in a reference picture;
calculating a compensation coefficient by using values of one or more first pixels neighboring the current block in the current picture and values of one or more second pixels neighboring the reference block in the reference picture;
when a value of the compensation coefficient is not “0”,
generating a changed reference block by applying the compensation coefficient to the reference block, and
setting the changed reference block to be a predicted block of the current block; and
when the value of the compensation coefficient is “0”,
setting the reference block to be the predicted block of the current block,
wherein the one or more first pixels and the one or more second pixels are pixels encoded prior to encoding the current block.
2. The inter prediction method as claimed in claim 1 , further comprising: encoding information for indicating that the changed reference block is selected as the predicted block.
3. An inter prediction method for encoding a video image, comprising:
determining a current motion vector of a current block in a current picture;
generating a reference block by interpolating pixels at a position indicated by the current motion vector in a reference picture;
calculating a compensation coefficient by using values of one or more first pixels neighboring the current block in the current picture and values of one or more second pixels neighboring the reference block in the reference picture;
generating a changed reference block by applying the compensation coefficient to the reference block, and setting the changed reference block to be a predicted block of the current block when a value of the compensation coefficient is within a predetermined range; and
setting the reference block to be the predicted block of the current block when a value of the compensation coefficient is out of the predetermined range,
wherein the one or more first pixels and the one or more second pixels are pixels encoded prior to encoding the current block,
wherein the predetermined range is identified by a maximum threshold and a minimum threshold.
4. The inter prediction method as claimed in claim 1 , further comprising:
re-determining the current motion vector after applying the compensation coefficient to pixels in the reference picture.
5. The inter prediction method as claimed in claim 1 , wherein the compensation coefficient is calculated based on a difference between an average of the one or more first pixels and an average of the one or more second pixels.
6. An inter prediction method for encoding a video image, comprising:
determining a current motion vector of a current block in a current picture;
generating a reference block by interpolating pixels at a position indicated by the current motion vector in a reference picture;
calculating a compensation coefficient by using values of one or more first pixels neighboring the current block in the current picture and values of one or more second pixels neighboring the reference block in the reference picture;
when the value of the compensation coefficient is not “0”,
generating a changed reference block by applying the compensation coefficient to the reference block, and
determining a predicted block of the current block based on the changed reference block; and
when the value of the compensation coefficient is “0”,
setting the reference block to be the predicted block of the current block,
wherein the one or more first pixels and the one or more second pixels are pixels encoded prior to encoding the current block,
wherein the changed reference block is generated by either subtracting the compensation coefficient from each pixel of the reference block or adding the compensation coefficient to each pixel of the reference block.
7. The inter prediction method as claimed in claim 6 , wherein each value of pixels of the changed reference block has a value within a preset range.
8. The inter prediction method as claimed in claim 6 , wherein the one or more first pixels and the one or more second pixels are selected based on a comparison between motion information of the current block and motion information of one or more neighboring blocks of the current block.
9. An inter prediction method for decoding a video image, comprising:
reconstructing a current motion vector of a current block in a current picture from a bitstream;
generating a reference block by interpolating pixels at a position indicated by the current motion vector in a reference picture;
calculating a compensation coefficient by using values of one or more first pixels neighboring the current block in the current picture and values of one or more second pixels neighboring the reference block in the reference picture;
when a value of the compensation coefficient is not “0”,
generating a changed reference block by applying the compensation coefficient to the reference block; and
setting the changed reference block to be a predicted block of the current block; and
when the value of the compensation coefficient is “0”,
setting the reference block to be the predicted block of the current block,
wherein the one or more first pixels and the one or more second pixels are pixels decoded prior to decoding the current block.
10. The inter prediction method as claimed in claim 9 , further comprising:
extracting compensation coefficient usage information from the bitstream,
wherein the predicted block of the current block is determined based on the compensation coefficient when the compensation coefficient usage information indicates use of the compensation coefficient.
11. An inter prediction method for decoding a video image, comprising:
reconstructing a current motion vector of a current block in a current picture from a bitstream;
generating a reference block by interpolating pixels at a position indicated by the current motion vector in a reference picture;
calculating a compensation coefficient by using values of one or more first pixels neighboring the current block in the current picture and values of one or more second pixels neighboring the reference block in the reference picture;
generating a changed reference block by applying the compensation coefficient to the reference block, and
setting the changed reference block to be a predicted block of the current block, when a value of the compensation coefficient is within a predetermined range; and
setting the reference block to be the predicted block of the current block when the value of the compensation coefficient is out of the predetermined range,
wherein the one or more first pixels and the one or more second pixels are pixels decoded prior to decoding the current block,
wherein the predetermined range is identified by a maximum threshold and a minimum threshold.
12. The inter prediction method as claimed in claim 9 , wherein the one or more first pixels and the one or more second pixels are selected based on a comparison between motion information of the current block and motion information of one or more neighboring blocks adjacent to the current block.
13. The inter prediction method as claimed in claim 9 , wherein the current block is a subblock of a macroblock.
14. The inter prediction method as claimed in claim 9 , wherein when one or more neighboring reference blocks indicated by the motion information of the one or more neighboring blocks are neighboring the reference block in the reference picture,
one or more pixels located within the one or more neighboring blocks are selected as the one or more first pixels, and
one or more pixels located within the one or more neighboring reference blocks are selected as the one or more first pixels.
15. The inter prediction method as claimed in claim 12 , wherein when one or more differences between the current motion vector and one or more motion vectors of the one or more neighboring blocks are smaller than a reference threshold,
one or more pixels located within the one or more neighboring blocks are selected as the one or more first pixels, and
one or more pixels located within one or more neighboring reference blocks are selected as the one or more second pixels, the one or more neighboring reference blocks being indicated by motion information of the one or more neighboring blocks.
16. The inter prediction method as claimed in claim 15 , wherein when one or more distances between the current motion vector and the one or more motion vectors of the one or more neighboring blocks smaller than a distance threshold, the one or more differences are smaller than the reference threshold.
17. The inter prediction method as claimed in claim 9 , wherein the compensation coefficient is calculated based on a difference between an average of the one or more first pixels and an average of the one or more second pixels.
18. An inter prediction method for decoding a video image, comprising:
reconstructing a current motion vector of a current block in a current picture from a bitstream;
generating a reference block by interpolating pixels at a position indicated by the current motion vector in a reference picture;
calculating a compensation coefficient by using values of one or more first pixels neighboring the current block in the current picture and values of one or more second pixels neighboring the reference block in the reference picture;
generating a changed reference block by applying the compensation coefficient to the reference block, and determining a predicted block of the current block based on the changed reference block, when a value of the compensation coefficient is within a predetermined range; and
setting the reference block to be the predicted block of the current block when the value of the compensation coefficient is out of the predetermined range,
wherein the one or more first pixels and the one or more second pixels are pixels decoded prior to decoding the current block,
wherein the changed reference block is generated by either subtracting the compensation coefficient from each pixel of the reference block or adding the compensation coefficient to each pixel of the reference block,
wherein the predetermined range is identified by a maximum threshold and a minimum threshold.
19. The inter prediction method as claimed in claim 9 , wherein each value of pixels of the changed reference block has a value within a preset range.