Image processing method and apparatus
An image processing method and apparatus includes transforming a first image to obtain a first transform coefficient set; transforming a second image, or transforming a difference image between the first image and a second image, to obtain a second transform coefficient set; selecting a first group of transform coefficients from the first transform coefficient set according to magnitudes of transform coefficients in the first transform coefficient set, where magnitudes of transform coefficients in the first group of transform coefficients meet a preset threshold condition; determining an image difference between the first image and the second image according to the first group of transform coefficients and the second transform coefficient set; and processing the first image and the second image according to the image difference.
1. An image processing method, comprising:
transforming a first image in a first manner to obtain a first transform coefficient set;
transforming a second image in the same manner to obtain a second transform coefficient set, or transforming a difference image between the first image and a second image in the same manner to obtain the second transform coefficient set;
selecting a first group of transform coefficients from the first transform coefficient set according to magnitudes of transform coefficients in the first transform coefficient set, wherein magnitudes of transform coefficients in the first group of transform coefficients meet a preset threshold condition;
determining an image difference between the first image and the second image according to the first group of transform coefficients and the second transform coefficient set; and
processing the first image and the second image according to the image difference.
2. The method according to claim 1 , wherein determining the image difference between the first image and the second image when the second transform coefficient set is obtained by transforming the second image with the transform comprises:
selecting, from the second transform coefficient set according to a one-to-one correspondence between transform coefficients in the first transform coefficient set and in the second transform coefficient set, a second group of transform coefficients that corresponds to the first group of transform coefficients; and
determining the image difference according to the first group of transform coefficients and the second group of transform coefficients.
3. The method according to claim 2 , wherein determining the image difference according to the first group of transform coefficients and the second group of transform coefficients comprises:
determining differences between corresponding transform coefficients in the first group of transform coefficients and in the second group of transform coefficients; and
determining a sum of the differences between the corresponding transform coefficients as the image difference.
4. The method according to claim 2 , wherein both the first group of transform coefficients and the second group of transform coefficients are divided into N subgroups in a same manner, wherein N is an integer, and wherein determining the image difference according to the first group of transform coefficients and the second group of transform coefficients comprises:
determining N target values, wherein an i th target value in the N target values is a sum of differences between corresponding transform coefficients in an i th subgroup of the first group of transform coefficients and in an i th subgroup of the second group of transform coefficients; and
performing weighted summation on the N target values according to weighting coefficients of the N subgroups to obtain the image difference.
5. The method according to claim 2 , wherein determining the image difference according to the first group of transform coefficients and the second group of transform coefficients comprises:
determining a first target value, wherein the first target value is a sum of differences between corresponding transform coefficients in the first group of transform coefficients and in the second group of transform coefficients;
determining a second target value, wherein the second target value is a sum of differences between corresponding transform coefficients in a first remaining group of transform coefficients other than the first group of transform coefficients in the first transform coefficient set and in a second remaining group of transform coefficients other than the second group of transform coefficients in the second transform coefficient set; and
performing weighted summation on the first target value and the second target value according to a weighting coefficient of the first target value and a weighting coefficient of the second target value to obtain the image difference.
6. The method according to claim 1 , wherein determining the image difference between the first image and the second image when the second transform coefficient set is a transform coefficient set that is obtained by transforming the difference image between the first image and the second image in the same manner, comprises:
selecting, from the second transform coefficient set according to a one-to-one correspondence between transform coefficients in the first transform coefficient set and in the second transform coefficient set, a second group of transform coefficients that corresponds to the first group of transform coefficients; and
determining the image difference according to the second group of transform coefficients.
7. The method according to claim 6 , wherein determining the image difference according to the second group of transform coefficients comprises determining a sum of transform coefficients in the second group of transform coefficients as the image difference.
8. The method according to claim 6 , wherein the second group of transform coefficients comprises N subgroups, wherein N is an integer, and wherein determining the image difference according to the second group of transform coefficients comprises:
determining N target values, wherein an i th target value is a sum of transform coefficients in an i th subgroup; and
performing weighted summation on the N target values according to weighting coefficients of the N target values, to obtain the image difference.
9. The method according to claim 6 , wherein the determining the image difference according to the second group of transform coefficients comprises:
determining a first target value, wherein the first target value is a sum of transform coefficients in the second group of transform coefficients;
determining a second target value, wherein the second target value is a sum of the second remaining group of transform coefficients other than the second group of transform coefficients in the second transform coefficient set; and
performing weighted summation on the first target value and the second target value according to a weighting coefficient of the first target value and a weighting coefficient of the second target value, to obtain the image difference.
10. The method according to claim 1 , wherein the first image is a target image and the second image is any candidate image in K candidate images, wherein K is an integer, and wherein processing the first image and the second image according to the image difference comprises:
determining a weighting coefficient of each candidate image according to an image difference between the target image and each candidate image; and
determining a filtered image of the target image according to pixel values of the K candidate images and weighting coefficients of the K candidate images.
11. The method according to claim 10 , wherein determining the weighting coefficient of each candidate image according to the image difference between the target image and each of the candidate images comprises determining the weighting coefficient of each of the candidate images according to Wk=b1 (−(Dk) a1 /h1) , wherein each of b1, a1, and h1 represents a positive real number, Dk represents an image difference between the first image and a k th candidate image, and Wk represents a weighting coefficient of the k th candidate image.
12. The method according to claim 10 , wherein determining the weighting coefficient of each candidate image according to the image difference between the target image and each candidate image comprises determining the weighting coefficient of each candidate image according to Wk=b2−(Dk) a2 /h2, wherein each of b2, a2, and h2 represents a positive real number, Dk represents an image difference between the first image and a k th candidate image, and Wk represents a weighting coefficient of the k th candidate image.
13. The method according to claim 10 , wherein determining the weighting coefficient of each candidate image according to the image difference between the target image and each candidate image comprises determining the weighting coefficient of each candidate image according to
Wk
=
h
3
b
3
+
(
Dk
)
a
3
,
wherein each of b3, a3, and h3 represents a positive real number, Dk represents an image difference between the first image and a k th candidate image, and Wk represents a weighting coefficient of the k th candidate image.
14. The method according to claim 10 , wherein determining the filtered image of the target image according to pixel values of the K candidate images and weighting coefficients of the K candidate images comprises determining the filtered image according to
Pf
j
=
W
0
×
P
0
j
+
∑
k
=
1
K
Wk
×
Pk
j
W
0
+
∑
k
=
1
K
Wk
,
wherein Pf j represents a pixel value of the filtered image at a j th pixel point, W 0 represents a weighting coefficient of the first image, Wk represents a weighting coefficient of a k th candidate image, P 0 j represents a pixel value of the first image at a j th pixel point, and Pk j represents a pixel value of the k th candidate image at a j th pixel point.
15. An image processing apparatus, comprising:
a processor;
a first transformer coupled to the processor and configured to transform a first image in a first manner to obtain a first transform coefficient set;
a second transformer coupled to the processor and configured to transform a second image in the same manner or transform a difference image between the first image and a second image in the same manner to obtain a second transform coefficient set;
a selector coupled to the processor and configured to select a first group of transform coefficients from the first transform coefficient set according to magnitudes of transform coefficients in the first transform coefficient set that is obtained by the first transformer, wherein magnitudes of transform coefficients in the first group of transform coefficients meet a preset threshold condition;
a determiner coupled to the processor and configured to determine an image difference between the first image and the second image according to the first group of transform coefficients selected by the selector and the second transform coefficient set obtained by the second transformer; and
the processor configured to process the first image and the second image according to the image difference determined by the determiner.
16. The apparatus according to claim 15 , wherein the determiner is further configured to:
select, from the second transform coefficient set according to a one-to-one correspondence between transform coefficients in the first transform coefficient set and in the second transform coefficient set, a second group of transform coefficients that corresponds to the first group of transform coefficients; and
determine the image difference according to the first group of transform coefficients and the second group of transform coefficients.
17. The apparatus according to claim 16 , wherein the determiner is further configured to:
determine differences between corresponding transform coefficients in the first group of transform coefficients and in the second group of transform coefficients; and
determine a sum of the differences between the corresponding transform coefficients as the image difference.
18. The apparatus according to claim 16 , wherein both the first group of transform coefficients and the second group of transform coefficients are divided into N subgroups in a same manner, wherein N is an integer, and wherein the determiner is further configured to:
determine N target values, wherein an i th target value in the N target values is a sum of differences between corresponding transform coefficients in an i th subgroup of the first group of transform coefficients and in an i th subgroup of the second group of transform coefficients; and
perform weighted summation on the N target values according to weighting coefficients of the N subgroups to obtain the image difference.
19. The apparatus according to claim 16 , wherein the determiner is configured to:
determine a first target value, wherein the first target value is a sum of differences between corresponding transform coefficients in the first group of transform coefficients and in the second group of transform coefficients;
determine a second target value, wherein the second target value is a sum of differences between corresponding transform coefficients in a first remaining group of transform coefficients other than the first group of transform coefficients in the first transform coefficient set and in a second remaining group of transform coefficients other than the second group of transform coefficients in the second transform coefficient set; and
perform weighted summation on the first target value and the second target value according to a weighting coefficient of the first target value and a weighting coefficient of the second target value to obtain the image difference.
20. The apparatus according to claim 15 , wherein the determiner is further configured to:
select, from the second transform coefficient set according to a one-to-one correspondence between transform coefficients in the first transform coefficient set and in the second transform coefficient set, a second group of transform coefficients that is corresponding to the first group of transform coefficients; and
determine the image difference according to the second group of transform coefficients.
21. The apparatus according to claim 20 , wherein the determiner is configured to determine a sum of transform coefficients in the second group of transform coefficients as the image difference.
22. The apparatus according to claim 20 , wherein the second group of transform coefficients comprises N subgroups, wherein N is an integer, and wherein the determiner is further configured to:
determine N target values, wherein an i th target value is a sum of transform coefficients in an i th subgroup; and
perform weighted summation on the N target values according to weighting coefficients of the N target values, to obtain the image difference.
23. The apparatus according to claim 20 , wherein the determiner is further configured to:
determine a first target value, wherein the first target value is a sum of transform coefficients in the second group of transform coefficients;
determine a second target value, wherein the second target value is a sum of the second group of remaining transform coefficients other than the second group of transform coefficients in the second transform coefficient set; and
perform weighted summation on the first target value and the second target value according to a weighting coefficient of the first target value and a weighting coefficient of the second target value to obtain the image difference.
24. The apparatus according to claim 15 , wherein the first image is a target image and the second image is any candidate image in K candidate images, wherein K is an integer, and wherein the processor is further configured to:
determine a weighting coefficient of each candidate image according to an image difference between the target image and each candidate image; and
determine a filtered image of the target image according to pixel values of the K candidate images and weighting coefficients of the K candidate images.
25. The apparatus according to claim 24 , wherein the determiner is configured to determine the weighting coefficient of each candidate image according to Wk=b1 (−(Dk) a1 /h1) , and wherein each of b1, a1, and h1 represents a positive real number, Dk represents an image difference between the first image and a k th candidate image, and Wk represents a weighting coefficient of the k th candidate image.
26. The apparatus according to claim 24 , wherein the determiner is configured to determine the weighting coefficient of each candidate image according to Wk=b2−(Dk) a2 /h2, and wherein each of b2, a2, and h2 represents a positive real number, Dk represents an image difference between the first image and a k th candidate image, and Wk represents a weighting coefficient of the k th candidate image.
27. The apparatus according to claim 24 , wherein the determiner is configured to determine the weighting coefficient of each candidate image according to
Wk
=
h
3
b
3
+
(
Dk
)
a
3
,
and wherein each of b3, a3, and h3 represents a positive real number, Dk represents an image difference between the first image and a k th candidate image, and Wk represents a weighting coefficient of the k th candidate image.
28. The apparatus according to claim 24 , wherein the processor is configured to determine the filtered image according to
Pf
j
=
W
0
×
P
0
j
+
∑
k
=
1
K
Wk
×
Pk
j
W
0
+
∑
k
=
1
K
Wk
,
and wherein Pf j represents a pixel value of the filtered image at a j th pixel point, W 0 represents a weighting coefficient of the first image, Wk represents a weighting coefficient of a k th candidate image, P 0 j represents a pixel value of the first image at a j th pixel point, and Pk j represents a pixel value of the k th candidate image at a j th pixel point.