Method of dimming backlight assembly
View Patent ↗A plurality of gray-scale values is extracted from image signals corresponding to a dimming area to calculate a mean value of the gray-scale values, and at least one of a variance, a standard deviation, a kurtosis, a skewness, a central moment, and an image moment is calculated using the mean value. Then, a representative gray-scale value corresponding to the dimming area is determined using the calculated values, and a dimming function for the light sources included in the dimming area is determined based on the representative gray-scale value. Then, the light sources included in the dimming area are driven based on the dimming function.
1. A method of dimming a backlight assembly of a display panel comprising a plurality of light sources divided into at least one dimming area, the method comprising:
providing image signals to the display panel;
extracting a plurality of gray-scale values from image signals corresponding to the dimming area to calculate at least one of a mean value, a median value or a mode value of the gray-scale values;
calculating at least one of a variance, a standard deviation, a kurtosis, a skewness, a central moment, and an image moment using at least one of a mean value, a median value or a mode value, wherein the image moment comprises a raw image moment of an n-th degree or lower and a central image moment of the n-th degree or lower, where n is a number of the gray-scale values;
calculating a maximum value of the gray-scale values;
determining a representative gray-scale value corresponding to the dimming area using the calculated values;
determining a dimming function for the light sources included in the dimming area based on the representative gray-scale value; and
driving the light sources included in the dimming area based on the dimming function,
wherein the representative gray-scale value GRE is represented by the following formula:
γ 2 ≧0 ,GRE=α×m +(1−α)× P,
γ 2 <0 ,GRE=α×m +(1−α)× P−βγ 1 ,
wherein
m denotes the at least one of a mean value, a median value or a mode value,
P denotes the maximum value,
γ 1 denotes the kurtosis, γ 2 denotes the skewness,
α
=
1
C
+
K
and β are predetermined constants,
C is a predetermined constant satisfying 0.5≦C≦1.5,
K is Max(| x |, | y |, √{square root over (|μ 11 |)}) if
Max
(
μ
20
,
μ
02
,
μ
12
3
,
μ
21
3
,
μ
30
3
,
μ
03
3
)
≥
T
and zero (0) if
Max
(
μ
20
,
μ
02
,
μ
12
3
,
μ
21
3
,
μ
30
3
,
μ
03
3
)
<
T
,
T denotes a predetermined threshold value,
x denotes an x-axis average raw image moment of the gray-scale values,
y denotes a y-axis average raw image moment of the gray-scale values, and
μ ij denotes the central image moment of an i-th degree along the x-axis and of a j-th degree along the y-axis.
2. The method of claim 1 , wherein determining the dimming function comprises:
extracting a target brightness value corresponding to the representative gray-scale value using a target gamma curve;
extracting a light-emitting brightness value of the light sources using the target brightness value; and
determining the dimming function for the light sources included in the dimming area in response to the light-emitting brightness value.
3. A method of dimming a backlight assembly of a display panel comprising a plurality of light sources divided into at least one dimming area, the method comprising:
providing image signals to the display panel;
extracting a plurality of gray-scale values from image signals corresponding to the dimming area to calculate at least one of a mean value, a median value or a mode value of the gray-scale values;
calculating at least one of a variance, a standard deviation, a kurtosis, a skewness, a central moment, and an image moment using the at least one of a mean value, a median value or a mode value, wherein the image moment comprises a raw image moment of an n-th degree or lower and a central image moment of the n-th degree or lower, where n is a number of the gray-scale values;
determining a representative gray-scale value corresponding to the dimming area using the calculated values;
determining a dimming function for the light sources included in the dimming area based on the representative gray-scale value; and
driving the light sources included in the dimming area based on the dimming function,
wherein the representative gray-scale value GRE is represented by the following formula:
γ
1
≥
0
,
GRE
=
m
-
K
σ
+
γ
2
2
,
γ
1
<
0
,
GRE
=
m
+
K
σ
+
γ
2
2
,
wherein in denotes the at least one of a mean value, a median value or a mode value,
σ denotes the variance,
γ 1 denotes the kurtosis, γ 2 denotes the skewness, and
K is a predetermined constant satisfying K>0.
4. The method of claim 3 , wherein determining the dimming function comprises:
extracting a target brightness value corresponding to the representative gray-scale value using a target gamma curve;
extracting a light-emitting brightness value of the light sources using the target brightness value; and
determining the dimming function for the light sources included in the dimming area in response to the light-emitting brightness value.
5. A method of dimming a backlight assembly of a display panel comprising a plurality of light sources divided into at least one dimming area, the method comprising:
providing image signals to the display panel;
extracting a plurality of gray-scale values from image signals corresponding the dimming area to calculate at least one of a mean value, a median value or a mode value of the gray-scale values;
calculating at least one of a variance, a standard deviation, a kurtosis, a skewness, a central moment, and an image moment using the at least one of a mean value, a median value or a mode value, wherein the image moment comprises a raw image moment of an n-th degree or lower and a central image moment of the n-th degree or lower, where n is a number of the gray-scale values;
calculating a maximum value of the gray-scale values;
determining a representative gray-scale value corresponding to the dimming area using the calculated values;
determining a dimming function for the light sources included in the dimming area based on the representative gray-scale value; and
driving the light sources included in the dimming area based on the dimming function,
wherein the representative gray-scale value GRE is represented by the following formula:
GRE
=
α
1
m
+
α
2
σ
+
α
3
γ
1
+
α
4
γ
2
+
α
5
P
+
α
6
x
_
+
α
7
y
_
+
α
8
μ
11
+
α
9
μ
20
+
α
10
μ
02
+
α
11
μ
12
3
+
α
12
μ
21
3
+
α
13
μ
30
3
+
α
14
μ
03
3
,
wherein m denotes the at least one of a mean value, a median value or a mode value,
σ denotes the variance,
P denotes the maximum value,
γ 1 denotes the kurtosis, γ 2 denotes the skewness,
x denotes an x-axis average raw image moment of the gray-scale values,
y denotes a y-axis average raw image moment of the gray-scale values, and
μ ij denotes the central image moment of an i-th degree along the x-axis and of a j-th degree along the y-axis, and if
α 1 +α 2 +α 3 +α 4 +α 5 +α 5 +α 7 +α 8 +α 9 +α 10 +α 11 α 12 +α 13 +α 14 is 1, then each α i is greater than or equal to zero (0) and less than or equal to one (1) (0≦α i ≦1).
6. The method of claim 5 , wherein determining the dimming function comprises:
extracting a target brightness value corresponding to the representative gray-scale value using a target gamma curve;
extracting a light-emitting brightness value of the light sources using the target brightness value; and
determining the dimming function for the light sources included in the dimming area in response to the light-emitting brightness value.
7. A method of dimming a backlight assembly of a display panel comprising a plurality of light sources divided into at least one dimming area, the method comprising;
providing image signals to the display panel;
extracting a plurality of gray-scale values from image signals corresponding to the dimming area to calculate at least one of a mean value, a median value or a mode value of the gray-scale values;
calculating at least one of a variance, a standard deviation, a kurtosis, a skewness, a central moment, and an image moment using the at least one of a mean value, a median value or a mode value, wherein the image moment comprises a raw image moment of an n-th degree or lower and a central image moment of the n-th degree or lower, where n is a number of the gray-scale values;
calculating a maximum value of the gray-scale values;
determining a representative scale value corresponding to the dimming area using the calculated values;
determining a dimming function for the light sources included in the dimming area based on the representative gray-scale value; and
driving the light sources included in the dimming area based on the dimming function,
wherein the representative gray-scale value GRE is represented by the following formula:
A≦T 1 ,GRE=m,
A≧T 2 ,GRE=P,
wherein when A is greater than T 1 and less than T 2 (T 1 <A<T 2 ),
the representative gray-scale value satisfies GRE=α×m+(1−α)×P when the kurtosis γ 1 is greater than zero (γ 1 >0),
the representative gray-scale value satisfies
GRE=(1−β)×m+β×P when the kurtosis γ 1 is equal to or smaller than zero (γ≦0),
wherein A=| x |+| y |+√{square root over (|μ 11 |)}
x denotes an x-axis average raw image moment of the gray-scale values,
y denotes a y-axis average raw image moment of the gray-scale values,
μ ij denotes the central image moment of an i-th degree along the x-axis and of a j-th degree along the y-axis,
m denotes the at least one of a mean value, a median value or a mode value,
P denotes the maximum value,
γ 1 denotes the kurtosis, T 1 and T 2 are predetermined threshold values,
α=Kγ 1 K 2 , βγ 1 γ 2 ,
K denotes a predetermined constant, and γ 2 denotes the skewness.
8. The method of claim 7 , wherein determining the dimming function comprises:
extracting a target brightness value corresponding to the representative gray-scale value using a target gamma curve;
extracting a light-emitting brightness value of the light sources using the target brightness value; and
determining the dimming function for the light sources included in the dimming area in response to the light-emitting brightness value.