Method and apparatus for converting grayscale, and display device
The disclosure relates to a method and apparatus for converting a grayscale, and a display device, where color coordinates of respective pixel elements are determined according to grayscales corresponding to red sub-pixels, green sub-pixels, and blue sub-pixels in the respective pixel elements in image data of a frame to be displayed, and then the distances between the color coordinates of the respective pixel elements, and color coordinates of a preset white pixel on the panel, in a CIE chroma graph are determined; and the maximum grayscales of white sub-pixels in the respective pixel elements are further determined according to the respective determined distances and a preset segmentation function.
1. A method for converting a grayscale, the method comprising:
receiving image data of a frame to be displayed, wherein the image data of the frame to be displayed comprise grayscales corresponding respectively to red sub-pixels, green sub-pixels, and blue sub-pixels in respective pixel elements;
determining color coordinates of the respective pixel elements according to the grayscales corresponding to the red sub-pixels, the green sub-pixels, and the blue sub-pixels in the respective pixel elements;
determining distances between the color coordinates of the respective pixel elements and color coordinates of a preset white pixel on a panel, in a CIE chroma graph; and
determining a maximum grayscale of the white sub-pixels in the respective pixel elements according to respective determined distances and a preset segmentation function;
wherein the determining the maximum grayscale of the white sub-pixels in the respective pixel elements according to the respective determined distances and the preset segmentation function comprises:
for each pixel element, determining the maximum grayscale W pixel_max of the white sub-pixel in the pixel element in the equation of:
W
pixel
_
m
ax
=
f
(
k
)
*
W
ma
x
,
and
f
(
k
)
=
{
α
0
+
α
1
k
+
α
2
k
2
+
α
3
k
2
+
…
+
α
n
k
n
(
0
≤
k
≤
k
1
)
β
0
+
β
1
k
+
β
2
k
2
+
β
3
k
3
+
…
+
β
m
k
m
(
k
1
<
k
≤
1
)
,
wherein k represents the distance between the color coordinates of the pixel element, and the color coordinates of the preset white pixel on the panel, in the CIE chroma graph, W max represents a maximum of all normalized grayscales in the image data of the frame to be displayed, α n and β m represents coefficients respectively, n≥0 and n is an integer, m≥0 and m is an integer, and 0≤k 1 ≤1.
2. The method for converting a grayscale according to claim 1 , wherein k 1 =0.5, n=3, and m=2.
3. The method for converting a grayscale according to claim 1 , wherein the determining the color coordinates of the respective pixel elements according to the grayscales corresponding to the red sub-pixels, the green sub-pixels, and the blue sub-pixels in the respective pixel elements comprises:
for each pixel element, determining a simulation value X corresponding to the red sub-pixel, a simulation value Y corresponding to the green sub-pixel, and a simulation. value Z corresponding to the blue sub-pixel in the pixel element in the equation of:
(
X
Y
Z
)
=
(
X
R
X
G
X
B
Y
R
Y
G
Y
B
Z
R
Y
G
Z
B
)
*
(
R
G
B
)
,
wherein
(
X
R
X
G
X
B
Y
R
Y
G
Y
B
Z
R
Y
G
Z
B
)
represents coefficients, R represents the grayscale of the red sub-pixel in the pixel element, Ci represents the grayscale of the green sub-pixel in the pixel element, and B represents the gmyscale of the blue sub-pixel in the pixel element; and
determining the color coordinates (x, y) of the pixel element according to determined simulation value X corresponding to the red sub-pixel, simulation value corresponding to the green sub-pixel, and the simulation value Z corresponding to the blue sub-pixel in the equation of:
{
x
=
X
X
+
Y
+
Z
y
=
Y
X
+
Y
+
Z
.
4. An apparatus for converting a grayscale, the apparatus comprising:
a receiving module configured to receive image data of a frame to be displayed, wherein the image data of the frame to be displayed comprise grayscales corresponding respectively to red sub-pixels, green sub-pixels, and blue sub-pixels in respective pixel elements;
a color coordinate determining module configured to determine color coordinates of the respective pixel elements according to the grayscales corresponding to the red sub-pixels, the green sub-pixels, and the blue sub-pixels in the respective pixel elements;
a distance determining module configured to determine distances between the color coordinates of the respective pixel elements and color coordinates of a preset white pixel on the panel, in a CIE chroma graph; and
a grayscale determining module configured to determine a maximum grayscale of the white sub-pixels in the respective pixel elements according to the respective determined distances and a preset segmentation function;
wherein the grayscale determining module is configured, for each pixel element, to determine the maximum grayscale W pixel_max of the white sub-pixel in the pixel element in the equation of:
W
pixel
_
m
ax
=
f
(
k
)
*
W
ma
x
,
and
f
(
k
)
=
{
α
0
+
α
1
k
+
α
2
k
2
+
α
3
k
2
+
…
+
α
n
k
n
(
0
≤
k
≤
k
1
)
β
0
+
β
1
k
+
β
2
k
2
+
β
3
k
3
+
…
+
β
m
k
m
(
k
1
<
k
≤
1
)
,
wherein k represents the distance between the color coordinates of the pixel element, and the color coordinates of the preset white pixel on the panel, in the CIE chroma graph, W max represents the maximum of all the normalized grayscales in the image data of the frame to be displayed, α n and β m represents coefficients respectively, n≥0 and n is an integer, m≥0 and m is an integer, and, 0≤k 1 ≤1.
5. The apparatus for converting a grayscale according to claim 4 , wherein k 1 =0.5, n=3, and m=2.
6. The apparatus for converting a grayscale according to claim 4 , wherein the color coordinate determining module is configured, for each pixel element, to determine a simulation value X corresponding to the red sub-pixel, a simulation. value Y corresponding to the green sub-pixel, and a simulation value Z corresponding to the blue sub-pixel in the pixel. clement in the equation of:
(
X
Y
Z
)
=
(
X
R
X
G
X
B
Y
R
Y
G
Y
B
Z
R
Y
G
Z
B
)
*
(
R
G
B
)
,
wherein
(
X
R
X
G
X
B
Y
R
Y
G
Y
B
Z
R
Y
G
Z
B
)
represents coefficients, R represents the grayscale of the red sub-pixel in the pixel element, G represents the grayscale of the green sub-pixel in the pixel element, and B represents the grayscale of the blue sub-pixel in the pixel element; and
to determine the color coordinates (x, y) of the pixel element according to determined simulation value X corresponding to the red sub-pixel, simulation value Y corresponding to the green sub-pixel, and the simulation value Z corresponding to the blue sub-pixel in the equation of:
{
x
=
X
X
+
Y
+
Z
y
=
Y
X
+
Y
+
Z
.
7. A display device, comprising the apparatus for converting a grayscale according to claim 4 .
8. The display device according to claim 7 , wherein k 1 =0.5, n=3, and m=2.
9. The display device according to claim 7 , wherein the color coordinate determining module is configured, for each pixel element, to determine a simulation value X corresponding to the red sub-pixel, a simulation value Y corresponding to the green sub-pixel, and a simulation value Z. corresponding to the blue sub-pixel in the pixel element in the equation of:
(
X
Y
Z
)
=
(
X
R
X
G
X
B
Y
R
Y
G
Y
B
Z
R
Y
G
Z
B
)
*
(
R
G
B
)
,
wherein
(
X
R
X
G
X
B
Y
R
Y
G
Y
B
Z
R
Y
G
Z
B
)
represents coefficients, R represents the grayscale of the red sub-pixel in the pixel element, G represents the grayscale of the green sub-pixel in the pixel element, and B represents the grayscale of the blue sub-pixel in the pixel element; and
to determine the color coordinates (x, y) of the pixel element according to determined simulation value X corresponding to the red sub-pixel, simulation value Y corresponding to the green sub-pixel, and the simulation value Z corresponding to the blue sub-pixel in the equation of:
{
x
=
X
X
+
Y
+
Z
y
=
Y
X
+
Y
+
Z
.
10. The display device according to claim 7 , wherein the display device further comprises a display panel and a display driver, wherein the display panel comprises a plurality of pixel elements PX, each of which comprises a red sub-pixel R, a green sub-pixel G, a blue sub-pixel B, and a white sub-pixel W; and
the display driver is configured to drive the display panel to display an image, according to the maximum grayscales of the white sub-pixels in. the respective pixel elements, and the grayscales corresponding to the red sub-pixels, the green sub-pixels, and the blue sub-pixels in the respective pixel elements, determined by the apparatus for converting a grayscale.