Method for selecting content adaptive coding mode
View Patent ↗A method for selecting content adaptive coding mode can apply a critical value to update by taking the advantages of a content adaptive MCTF update method and a covered pixel detection algorithm and, at the same time, improve the image quality by selecting a block having improper motion information and converting it into a coding in screen mode. The method also provides a method for selecting content adaptive coding mode that can improve the conventional MCTF algorithm by reusing JND, which is used in content adaptive MCTF, to find a block that has improper coding information and selecting a block that has improper motion information.
1. A method of selecting a content adaptive coding mode, the method comprising:
retrieving motion information for a current block and generating a high frequency band image by using the retrieved motion information;
calculating a local dispersion value JND of a reference block of a reference image and calculating a sum JND sum of all local dispersion values and a sum U sum of extra data U being added to all even frames;
setting a coding in screen mode when the U sum value is greater than the first critical value after comparing the calculated U sum value to a first critical value JND sum +E B ;
comparing the calculated U sum value to a second critical value JND sum when the U sum value is equal to or smaller than the first critical value;
maintaining a content adaptive motion compensated temporal filtering mode for a corresponding block when the U sum value is equal to or smaller than the second critical value, and adjusting the JND as a critical value of the U when the U sum value is greater than the second critical value, the JND being changed based on a pixel value in the image;
proceeding an update process by using a conventional motion compensated temporal filtering method for each pixel in a block, the mode of which is not changed,
wherein the E B is a sum of a tolerance range V permitted for each pixel.
2. The method of claim 1 , wherein the retrieving of the motion information for a current block is performed through a prediction process by performing an MCTF using a lifting scheme and the reverse conversion by applying a wavelet filter.
3. The method of claim 1 , wherein the critical value is a permissible range of U according to a difference between a current pixel and its surrounding pixels.
4. The method of claim 1 , wherein the JND sum is calculated by
JND
sum
=
[
∑
x
=
1
B
x
∑
y
=
1
B
y
JND
s
(
x
,
y
)
S
]
,
and the U sum is calculated by
U
sum
=
∑
x
=
1
B
x
∑
y
=
1
B
y
U
[
s
i
(
x
,
y
)
]
,
and
wherein S is a coefficient representing the degree of effect by the JND, x and y are coordinates in the block, B x and B y are respectively the horizontal and vertical sizes of the block, V is a tolerance range of the U permitted for each pixel, and E B is a sum of the V.
5. The method of claim 1 , wherein the setting a coding in screen mode is for omitting the update process.
6. The method of claim 1 , wherein the adjusting the JND as a critical value of the U is for limiting the update process.
7. A method of selecting a content adaptive coding mode, the method comprising:
retrieving motion information for a current block and generating a high frequency band image by using the retrieved motion information;
calculating a local dispersion value JND of a reference block of a reference image and calculating a sum JND sum of all local dispersion values and a sum U sum of extra data U being added to all even frames;
applying a content adaptive motion compensated temporal filtering update when the U value is within the range of E B +JND sum S;
applying an update by adjusting the JND as a critical value of the U when the U value is within the range of E B +JND sum S but exceeds the range of JND sum S, the JND being changed based on a pixel value in the image;
modifying a coding mode of a corresponding block into a coding in screen mode when the U value is greater than E B +JND sum S,
wherein the S is a coefficient representing the degree of effect by the JND, and the E B is a sum of a tolerance range V permitted for each pixel.
8. The method of claim 7 , wherein the retrieving of the motion information for a current block is performed through a prediction process by performing an MCTF using a lifting scheme and the reverse conversion by applying a wavelet filter.
9. The method of claim 7 , wherein the critical value is a permissible range of U according to a difference between a current pixel and its surrounding pixels.
10. The method of claim 7 , wherein the JND sum is calculated by
JND
sum
=
[
∑
x
=
1
B
x
∑
y
=
1
B
y
JND
s
(
x
,
y
)
S
]
,
and the U sum is calculated by
U
sum
=
∑
x
=
1
B
x
∑
y
=
1
B
y
U
[
s
i
(
x
,
y
)
]
,
and
wherein S is a coefficient representing the degree of effect by the JND, x and y are coordinates in the block, B x and B y are respectively the horizontal and vertical sizes of the block, V is a tolerance range of the U permitted for each pixel, and E B is a sum of the V.
11. A non-transitory computer-readable storage medium encoded with computer-executable instructions, which when executed by a computer, cause the computer to perform a method comprising:
retrieving motion information for a current block and generating a high frequency band image by using the retrieved motion information;
calculating a local dispersion value JND of a reference block of a reference image and calculating a sum JND sum of all local dispersion values and a sum U sum of extra data U being added to all even frames;
setting a coding in screen mode when the U sum value is greater than the first critical value after comparing the calculated U sum value to a first critical value JND sum +E B ;
comparing the calculated U sum value to a second critical value JND sum when the U sum value is equal to or smaller than the first critical value;
maintaining a content adaptive motion compensated temporal filtering mode for a corresponding block when the U sum value is equal to or smaller than the second critical value, and adjusting the JND as a critical value of the U when the U sum value is greater than the second critical value, the JND being changed based on a pixel value in the image; and
proceeding an update process by using a conventional motion compensated temporal filtering method for each pixel in a block, the mode of which is not changed,
wherein E B the is a sum of a tolerance range V permitted for each pixel.
12. A non-transitory computer-readable storage medium encoded with computer-executable instructions, which when executed by a computer, cause the computer to perform a method comprising:
retrieving motion information for a current block and generating a high frequency band image by using the retrieved motion information;
calculating a local dispersion value JND of a reference block of a reference image and calculating a sum JND sum of all local dispersion values and a sum U sum of extra data U being added to all even frames;
applying a content adaptive motion compensated temporal filtering update when the U value is within the range of E B +JND sum S;
applying an update by adjusting the JND as a critical value of the U when the U value is within the range of E B +JND sum S but exceeds the range of JND sum S, the JND being changed based on a pixel value in the image;
modifying a coding mode of a corresponding block into a coding in screen mode when the U value is greater than E B +JND sum S,
wherein the S is a coefficient representing the degree of effect by the JND, and the E B is a sum of a tolerance range V permitted for each pixel.