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Display Subsystem Functional Description
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11
Y0
7.4.2.3.2 Color Space Conversion
The color space conversion module converts the video-encoded pixel values from YCbCr 4:2:2 format into
RGB24.
Figure 7-70
rotation parameters.
Figure 7-70. YCbCr 4:2:2 to YCbCr 4:4:4 (0- or 180-Degree Rotation)
Image data line (0- and 180- degree rotation)
Line n
Line n
Figure 7-71. YCbCr 4:2:2 to YCbCr 4:4:4 (90- or 270-Degree Rotation)
Image data line
(90- and 270-
degree
rotation)
The interpolation of the missing chrominance component is given by the equation in
Figure 7-72. Interpolation of the Missing Chrominance Component
First, to convert the YCbCr 4:2:2 encoded pixel values into YCbCr 4:4:4 format, the missing chrominance
samples (Cb and Cr) are interpolated using the average values of the two closest values on the same line
(1/2, 1/2) or are repeated from the second pixel in the same 32-bit container.
•
In case of rotation 0-degree, for the last pixel, the chrominance samples are duplicated using the
values from the previous pixel; otherwise, the chrominance samples are averaged using the two
adjacent values.
•
In case of 180-degree rotation, for the first pixel the chrominance samples missing are duplicated from
the adjacent pixel; otherwise, the chrominance samples are averaged using the two adjacent values.
•
In case of rotation 90- and 270-degree, the missing chrominance components are duplicated from the
adjacent pixel in the same 32-bit container.
1642
Display Subsystem
Public Version
Cb0
and
Figure 7-71
detail the YCbCr 4:2:2 conversion to YCbCr 4:4:4 depending on the
Last Pixel
½ ½
1
Line n+2
Line n
Line n+1
Cb
(
YCbCr
n
1
-
Cb
(
YCbCr
444
)
=
n
Cr
(
YCbCr
n
1
-
(
444
)
Cr
YCbCr
=
n
Copyright © 2009–2010, Texas Instruments Incorporated
10
Y1
YUV4:2:2
Luminance sample (Y)
Chrominance sample (Cb)
Chrominance sample (Cr)
YUV4:4:4
Line n+3
Luminance sample (Y)
Chrominance sample (Cb)
Chrominance sample (Cr)
422
)
Cb
(
YCbCr
422
+
n
1
+
2
422
)
Cr
(
YCbCr
422
+
n
1
+
2
SWPU177N – December 2009 – Revised November 2010
www.ti.com
9
8
7
6
5
4
3
2
Cr0
dss-061
dss-060
Figure
7-72.
)
(n
odd)
)
(n
odd)
dss-E062
1
0
dss-T072
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