Method and apparatus for video coding on pixel-wise prediction
A pixel-based video encoding apparatus includes a block prediction unit, a residual image generation unit, a pixel prediction unit, and an entropy-coding unit. The block prediction unit performs temporal or spatial prediction between a reference image and a current image in order to generate a prediction block corresponding to a current block to be encoded. The residual image generation unit generates a residual image block composed of a residual signal corresponding to a difference between pixels of the prediction block and pixels of the current block. The pixel prediction unit determines whether to apply differential pulse coded modulation to each of pixels of the residual image block based on a rate distortion optimization value. The entropy-coding unit performs entropy-coding on the residual image block.
1. A pixel-based video encoding apparatus comprising:
a block prediction unit performing temporal or spatial prediction between a reference image and a current image in order to generate a prediction block corresponding to a current block to be encoded;
a residual image generation unit generating a residual image block composed of a residual signal corresponding to a difference between pixels of the prediction block and pixels of the current block;
a pixel prediction unit determining whether to apply differential pulse coded modulation (DPCM) to each of pixels of the residual image block based on a rate distortion optimization (RDO) value calculated for case where DPCM is applied to each of the pixels of the residual image block and a RDO value calculated for case where DPCM is not applied to each of the pixels of the residual image block; and
an entropy-coding unit performing entropy-coding on the residual image block.
2. The pixel-based video encoding apparatus of claim 1 , further comprising a reference data generation unit decoding the residual image block in order to generate reference data for prediction of a next block.
3. The pixel-based video encoding apparatus of claim 2 , wherein the pixel prediction unit transmits a signal indicating whether DPCM has been applied to the reference data generation unit.
4. The pixel-based video encoding apparatus of claim 2 , further comprising:
a transformation unit transforming the residual image block obtained by the pixel prediction unit; and
a quantization unit quantizing the transformed residual image block and transmitting the quantized residual image block to the entropy-coding unit.
5. The pixel-based video encoding apparatus of claim 4 , wherein the reference data generation unit comprises:
an inverse quantization unit corresponding to the quantization unit and inversely quantizing the quantized residual image block; and
an inverse transformation unit corresponding to the transformation unit, inversely transforming the inversely quantized residual image block.
6. The pixel-based video encoding apparatus of claim 1 , wherein the pixel prediction unit applies DPCM by predicting a luminance value of a current pixel from luminance values of neighbor pixels located around the current pixel in the residual image block.
7. The pixel-based video encoding apparatus of claim 6 , wherein a luminance value {circumflex over (x)} KDP of the current pixel x is given by:
x
^
EDP
=
{
min
(
a
,
b
)
if
c
>
max
(
a
,
b
)
max
(
a
,
b
)
if
c
<
min
(
a
,
b
)
a
+
b
-
c
otherwise
where c indicates a luminance value of an edge pixel in the residual image block, and a and b indicate luminance values of neighbor pixels around the edge pixel with the luminance value of c, and
the neighbor pixel with the smaller luminance value between a and b is used as a prediction pixel for the current pixel x if c is largest among a, b, and c, the neighbor pixel with the larger luminance value between a and b is used as the prediction pixel for the current pixel x if c is smallest, and it is determined that there is no edge and the luminance value of the current pixel x is predicted using a+b−c in other cases.
8. A pixel-based video decoding apparatus comprising:
a reception unit receiving a bitstream including coefficients resulting from entropy-coding of a residual image block that selectively undergoes differential pulse coded modulation (DPCM) and a mode flag having information about whether DPCM has been applied to the residual image block;
a pixel reconstruction unit selectively performing inverse differential pulse coded modulation (IDPCM) on the coefficients based on the mode flag in order to reconstruct the residual image block; and
a motion compensation unit performing motion compensation based on the residual image block to which IDPCM is selectively applied.
9. The pixel-based video decoding apparatus of claim 8 , further comprising:
an inverse quantization unit inversely quantizing the received bitstream; and
an inverse transformation unit inversely transforming the inversely quantized bitstream and transmitting the inversely quantized bitstream to the pixel reconstruction unit.
10. The pixel-based video decoding apparatus of claim 8 , wherein the pixel reconstruction unit performs IDPCM by reconstructing a luminance value of a current pixel based on luminance values of neighbour pixels located around the current pixel in the residual image block.
11. A pixel-based video codec stored in a non-transitory media which includes a computer-readable media as well as a machine/computer comprising:
a residual image generation unit generating a prediction block corresponding to a current block to be encoded between a reference image and a current image and generating a residual image block composed of a residual signal corresponding to a difference between pixels of the prediction block and pixels of the current block;
a pixel prediction unit determining whether to apply differential pulse coded modulation (DPCM) to each of pixels of the residual image block based on a rate distortion optimization (RDO) value calculated for the case where DPCM is applied to each of the pixels of the residual image block and a RDO value calculated for the case where DPCM is not applied to each of the pixels of the residual image block;
a pixel reconstruction unit selectively performing inverse differential pulse coded modulation (IDPCM) on a bitstream generated by entropy-coding the residual image block in order to reconstruct the residual image block; and
a motion compensation unit performing motion compensation based on the residual image block to which IDPCM is selectively applied.
12. The pixel-based video codec of claim 11 , wherein the pixel prediction unit transmits information about whether DPCM has been applied to the pixel reconstruction unit through the bitstream.
13. The pixel-based video codec of claim 11 , further comprising a reference data generation unit decoding the residual image block to which DPCM has been selectively applied, in order to generate reference data for prediction of a next block.
14. The pixel-based video codec of claim 13 , wherein the pixel prediction unit transmits a signal indicating whether DPCM has been applied to the reference data generation unit.
15. The pixel-based video codec of claim 11 , wherein the pixel prediction unit performs DPCM by predicting a luminance value of the current pixel from luminance values of neighbor pixels around a current pixel in the residual image block and the pixel reconstruction unit performs IDPCM by reconstructing the luminance value of the current pixel based on the luminance values of the neighbour pixels around the current pixel in the residual image block.
16. The pixel-based video codec of claim 15 , wherein a luminance value {circumflex over (x)} EDP of the current pixel x is given by:
x
^
EDP
=
{
min
(
a
,
b
)
if
c
>
max
(
a
,
b
)
max
(
a
,
b
)
if
c
<
min
(
a
,
b
)
a
+
b
-
c
otherwise
where c indicates a luminance value of an edge pixel in the residual image block, and a and b indicate luminance values of neighbor pixels around the edge pixel with the luminance value of c, and
the neighbor pixel with the smaller luminance value between a and b is used as a prediction pixel for the current pixel x if c is largest among a, b, and c, the neighbor pixel with the larger luminance value between a and b is used as the prediction pixel for the current pixel x if c is smallest, and it is determined that there is no edge and the luminance value of the current pixel x is predicted using a+b−c in other cases.
17. A pixel-based video codec stored in non-transitory media which includes a computer-readable media as well as a machine/computer comprising:
a block identification unit identifying the encoding mode of a current block of an input video frame and whether the current block is an intra-mode block or an inter-mode block; and
a prediction mode determination unit determining a prediction mode for the current block based on a rate distortion optimization (RDO) value calculated for the case where DPCM is applied to the current block and a RDO value calculated for the case where DPCM is not applied to the current block if the current block is an intra-mode block.
18. The pixel-based video codec of claim 17 , further comprising:
a residual image generation unit generating a prediction block corresponding to the current block in the determined prediction mode and generating a residual image block composed of a residual signal corresponding to a difference between pixels of the prediction block and pixels of the current block; and
an entropy-coding unit performing entropy-coding on the residual image block.
19. The pixel-based video codec of claim 18 , further comprising a reference data generation unit decoding the residual image block in order to generate reference data for prediction of a next block.
20. The pixel-based video codec of claim 19 , further comprising:
a transformation unit transforming the residual image block; and
a quantization unit quantizing the transformed residual image block and transmitting the quantized residual image block to the entropy-coding unit.
21. The pixel-based video codec of claim 20 , wherein the reference data generation unit comprises:
an inverse quantization unit inversely quantizing the received bitstream; and
an inverse transformation unit inversely transforming the inversely quantized bitstream and transmitting the inversely quantized bitstream to the pixel reconstruction unit.
22. A pixel-based video encoding method comprising:
generating a prediction block corresponding to a current block to be encoded by performing temporal or spatial prediction between a reference image and a current image;
generating a residual image block composed of a residual signal corresponding to a difference between pixels of the prediction block and pixels of the current block;
performing pixel prediction by determining whether to apply differential pulse coded modulation (DPCM) to each of pixels of the residual image block based on a rate distortion optimization (RDO) value calculated for the case where DPCM is applied to each of the pixels of the residual image block and a RDO value calculated for the case where DPCM is not applied to each of the pixels of the residual image block; and
performing entropy-coding on the residual image block.
23. The pixel-based video encoding method of claim 22 , further comprising generate reference data for prediction of a next block by decoding the residual image block.
24. The pixel-based video encoding method of claim 23 , wherein the performing pixel prediction comprises transmits a signal indicating whether DPCM has been applied to the generating reference data.
25. The pixel-based video encoding method of claim 23 , further comprising transforming and quantizing the residual image block obtained by the pixel prediction.
26. The pixel-based video encoding method of claim 22 , wherein DPCM is performed by predicting a luminance value of a current pixel from luminance values of neighbor pixels around the current pixel in the residual image block.
27. The pixel-based video encoding method of claim 26 , wherein a luminance value {circumflex over (x)} EDP of the current pixel x is given by:
x
^
EDP
=
{
min
(
a
,
b
)
if
c
>
max
(
a
,
b
)
max
(
a
,
b
)
if
c
<
min
(
a
,
b
)
a
+
b
-
c
otherwise
where c indicates a luminance value of an edge pixel in the residual image block, and a and b indicate luminance values of neighbor pixels around the edge pixel with the luminance value of c, and
the neighbor pixel with the smaller luminance value between a and b is used as a prediction pixel for the current pixel x if c is largest among a, b, and c, the neighbor pixel with the larger luminance value between a and b is used as the prediction pixel for the current pixel x if c is smallest, and it is determined that there is no edge and the luminance value of the current pixel x is predicted using a+b−c in other cases.
28. A non-transitory computer-readable medium having recorded thereon a program for implementing the pixel-based video encoding method claimed in any one of claims 22 through 27 and claims 32 through 42 and the pixel-based decoding method claimed in any one of claims 29 through 31 .
29. A pixel-based video decoding method comprising:
receiving a bitstream including coefficients resulting from entropy-coding of a residual image block that selectively undergoes differential pulse coded modulation (DPCM) and a mode flag having information about whether DPCM has been applied to the residual image block;
performing pixel reconstruction by selectively performing inverse differential pulse coded modulation (IDPCM) on the coefficients based on the mode flag in order to reconstruct the residual image block; and
performing motion compensation based on the residual image block to which IDPCM is selectively applied.
30. The pixel-based video decoding method of claim 29 , further comprising inversely quantizing and inversely transforming the received bitstream.
31. The pixel-based video decoding method of claim 29 , wherein the performing pixel reconstruction comprises performing IDPCM by reconstructing a luminance value of a current pixel based on luminance values of neighbour pixels around the current pixel in the residual image block.
32. A pixel-based video encoding method comprising:
generating a prediction block corresponding to a current block to be encoded between a reference image and a current image and generating a residual image block composed of a residual signal corresponding to a difference between pixels of the prediction block and pixels of the current block;
performing pixel prediction by determining whether to apply differential pulse coded modulation (DPCM) to each of pixels of the residual image block based on a rate distortion optimization (RDO) value calculated for the case where DPCM is applied to each of the pixels of the residual image block and a RDO value calculated for the case where DPCM is not applied to each of the pixels of the residual image block;
performing pixel reconstruction by selectively performing inverse differential pulse coded modulation (IDPCM) on a bitstream generated by entropy-coding the residual image in order to reconstruct the residual image block; and
performing motion compensation based on the residual image block to which IDPCM is selectively applied.
33. The pixel-based video encoding method of claim 32 , wherein the performing pixel prediction transmits information about whether DPCM has been applied to the performing pixel reconstruction through the bitstream.
34. The pixel-based video encoding method of claim 33 , further comprising generating reference data for prediction of a next block by decoding the residual image block to which DPCM has been selectively applied.
35. The pixel-based video encoding method of claim 34 , the performing pixel prediction further comprising, transmitting a signal indicating whether DPCM has been applied to the generating reference data.
36. The pixel-based video encoding method of claim 32 , wherein the performing pixel prediction comprises performing DPCM by predicting a luminance value of a current pixel from luminance values of neighbor pixels around the current pixel in the residual image block.
37. The pixel-based video encoding method of claim 36 , wherein a luminance value {circumflex over (x)} EDP of the current pixel x is given by:
x
^
EDP
=
{
min
(
a
,
b
)
if
c
>
max
(
a
,
b
)
max
(
a
,
b
)
if
c
<
min
(
a
,
b
)
a
+
b
-
c
otherwise
where c indicates a luminance value of an edge pixel in the residual image block, and a and b indicate luminance values of neighbor pixels around the edge pixel with the luminance value of c, and
the neighbor pixel with the smaller luminance value between a and b is used as a prediction pixel for the current pixel x if c is largest among a, b, and c, the neighbor pixel with the larger luminance value between a and b is used as the prediction pixel for the current pixel x if c is smallest, and it is determined that there is no edge and the luminance value of the current pixel x is predicted using a+b−c in other cases.
38. A pixel-based video encoding method comprising:
identifying the encoding mode of a current block of an input video frame and whether the current block is an intra-mode block or an inter-mode block; and
determining a prediction mode for the current block based on a rate distortion optimization (RDO) value calculated for the case where DPCM is applied to the current block and a RDO value calculated for the case where DPCM is not applied to the current block if the current block is the intra-mode block.
39. The pixel-based video encoding method of claim 38 , further comprising:
generating a prediction block corresponding to the current block in the determined prediction mode and generating a residual image block composed of a residual signal corresponding to a difference between pixels of the prediction block and pixels of the current block; and
performing entropy-coding on the residual image block.
40. The pixel-based video encoding method of claim 39 , further comprising generating reference data for prediction of a next block by decoding the residual image block.
41. The pixel-based video encoding method of claim 40 , further comprising transforming and quantizing the residual image block.
42. The pixel-based video encoding method of claim 41 , wherein the generating reference data comprises inversely quantizing and inversely transforming the received bitstream.