Adaptive color-temperature calibration system and method
View Patent ↗An adaptive color-temperature calibration system and method are disclosed. A chrominance generation unit generates a chrominance criterion according to an input pixel. A matrix generation unit generates a calibration matrix according to the chrominance criterion and a basis matrix. A color calibration unit then performs color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel.
1. An adaptive color-temperature calibration system, comprising:
a chrominance generation unit configured to generate a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
a matrix generation unit configured to generate a calibration matrix according to the chrominance criterion and a basis matrix; and
a color calibration unit configured to perform color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein the input pixel is represented by red (R), green (G) and blue (B) in RGB color space, and the color calibration unit performs color-temperature calibration by multiplying the input pixel by the generated calibration matrix A according to matrix multiplication:
[
Rout
Gout
Bout
]
=
[
Rin
Gin
Bin
]
·
A
=
[
Rin
Gin
Bin
]
·
[
a
11
a
12
a
13
a
21
a
22
a
23
a
31
a
32
a
33
]
wherein [Rout Gout Bout] is the output pixel, [Rin Gin Bin] is the input pixel, and a 11 through a 33 are constants.
2. An adaptive color-temperature calibration system, comprising:
a chrominance generation unit configured to generate a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
a matrix generation unit configured to generate a calibration matrix according to the chrominance criterion and a basis matrix; and
a color calibration unit configured to perform color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein the basis matrix Al has a form expressed as follows:
A
1
=
[
a
0
0
0
b
0
0
0
c
]
where a, b and c are constants.
3. An adaptive color-temperature calibration system, comprising:
a chrominance generation unit configured to generate a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
a matrix generation unit configured to generate a calibration matrix according to the chrominance criterion and a basis matrix; and
a color calibration unit configured to perform color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein the input pixel is represented by red (R), green (G) and blue (B) in RGB color space, and the chrominance criterion Δs is defined as follows:
Δ
s
=
max
(
RGB
)
-
min
(
RGB
)
max
(
RGB
)
wherein max(RGB) is a maximum value of R, G and B of the input pixel, and min(RGB) is a minimum value of R, G and B of the input pixel.
4. The system of claim 2 , wherein the basis matrix is obtained by assuming that the input pixel is white.
5. An adaptive color-temperature calibration system, comprising:
a chrominance generation unit configured to generate a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
a matrix generation unit configured to generate a calibration matrix according to the chrominance criterion and a basis matrix; and
a color calibration unit configured to perform color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein (1) the calibration matrix is generated to be the basis matrix when the chrominance criterion is lesser than or equal to a pre-determined first threshold; (2) the calibration matrix is generated to be a unit matrix when the chrominance criterion is greater than a pre-determined second threshold that is greater than the first threshold; (3) the calibration matrix is generated by linearly interpolating the basis matrix and the unit matrix when the chrominance criterion is between the first threshold and the second threshold.
6. The system of claim 5 , wherein the calibration matrix A in the case (3) is expressed as follows:
A=α.A 1+(1−α). A 2
wherein A 1 represents the basis matrix, A 2 represents the unit matrix, TH 1 is the first threshold, TH 2 is the second threshold, Δs is the chrominance criterion, and α=(TH 2 −Δs)/(TH 2 −TH 1 ).
7. An adaptive color-temperature calibration method, comprising:
generating a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
generating a calibration matrix according to the chrominance criterion and a basis matrix; and
performing color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein the input pixel is represented by red (R), green (G) and blue (B) in RGB color space, and the step of color-temperature calibration comprises:
multiplying the input pixel by the generated calibration matrix A according to matrix multiplication:
[
Rout
Gout
Bout
]
=
[
Rin
Gin
Bin
]
·
A
=
[
Rin
Gin
Bin
]
·
[
a
11
a
12
a
13
a
21
a
22
a
23
a
31
a
32
a
33
]
wherein [Rout Gout Bout] is the output pixel, [Rin Gin Bin] is the input pixel, and a ll through a 33 are constants.
8. An adaptive color-temperature calibration method, comprising:
generating a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
generating a calibration matrix according to the chrominance criterion and a basis matrix; and
performing color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein the input pixel is represented by red (R), green (G) and blue (B) in RGB color space, and the chrominance criterion Δs is defined as follows:
Δ
s
=
max
(
RGB
)
-
min
(
RGB
)
max
(
RGB
)
wherein max(RGB) is a maximum value of R, G and B of the input pixel, and min(RGB) is a minimum value of R, G and B of the input pixel.
9. An adaptive color-temperature calibration method, comprising:
generating a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
generating a calibration matrix according to the chrominance criterion and a basis matrix; and
performing color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein the basis matrix Al has a form expressed as follows:
A
1
=
[
a
0
0
0
b
0
0
0
c
]
where a, b and c are constants.
10. The method of claim 9 , further comprising a step of obtaining the basis matrix by assuming that the input pixel is white.
11. An adaptive color-temperature calibration method, comprising:
generating a chrominance criterion according to an input pixel, the chrominance criterion indicating amount of chrominance in the input pixel;
generating a calibration matrix according to the chrominance criterion and a basis matrix; and
performing color-temperature calibration on the input pixel according to the generated calibration matrix, thereby generating an output pixel;
wherein (1) the calibration matrix is generated to be the basis matrix when the chrominance criterion is lesser than or equal to a pre-determined first threshold; (2) the calibration matrix is generated to be a unit matrix when the chrominance criterion is greater than a pre-determined second threshold that is greater than the first threshold; (3) the calibration matrix is generated by linearly interpolating the basis matrix and the unit matrix when the chrominance criterion is between the first threshold and the second threshold.
12. The method of claim 11 , wherein the calibration matrix A in the case (3) is expressed as follows:
A=α.A 1+(1−α). A 2
wherein A 1 represents the basis matrix, A 2 represents the unit matrix, TH 1 is the first threshold, TH 2 is the second threshold, Δs is the chrominance criterion, and α=(TH 2 −Δs)/(TH 2 −TH 1 ).