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Video Output Filtering
4-23Video Display PortSPRU629
Figure 4–20. 2x Co-Sited Scaling
2× upscaled output
YCbCr 4:2:2 co–sited
source pixels
Luma (Y)
sample
Y’
d’
= (–1Y
c
+ 17Y
d
+ 17Y
e
– 1Y
f
) / 32
Cb’
d
= (–1Cb
a
+ 17Cb
c
+ 17Cb
e
– 1Cb
g
) / 32
Cr’
d
= (–1Cr
a
+ 17Cr
c
+ 17Cr
e
– 1Cr
g
) / 32
–
Chroma (Cb/Cr)
samples
–
aa’ bb’ cc’ dd’ ee’ ff’
abcdefg
g
Cr’
c
= Cr
c
Cb’
c
= Cb
c
Y’
b
= Y
b
Figure 4–21. 2x Interspersed Scaling
2x upscaled
YCbCr 4:2:2
co-sited output
YCbCr 4:2:2
interspersed
source pixels
Luma (Y)
sample
Cb’
d
= (–3Cb
ab
+ 101Cb
cd
+ 33Cb
ef –
3Cb
gh
) / 128
Cr’
d
= (–3Cr
ab
+ 101Cr
cd
+ 33Cr
ef –
3Cr
gh
) / 128
–
Chroma (Cb/Cr)
samples
–
aa’ bb’ cc’ dd’ ee’ ff’
abcdefg
g
Y’
a
= Y
a
Cb’
e
= (–3Cb
ab
+ 33Cb
cd
+ 101Cb
ef –
3Cb
gh
) / 128
Cr’
e
= (–3Cr
ab
+ 33Cr
cd
+ 101Cr
ef –
3Cr
gh
) / 128
h’
Y’
e’
= (–1Y
d
+ 17Y
e
+ 17Y
f
– 1Y
g
) / 32
4.4.4 Edge Pixel Replication
Because four tap filters are used on the output, the first and last two pixels on
each line must be mirrored. An example of how the filter uses the mirrored pixels
for the luminance filter (2× co-sited) is shown in Figure 4–22.
Figure 4–22. Output Edge Pixel Replication
a
–
–
a’ bb’ c
a
n–1’ n
n’n–2n–2’ n–1
abc nn–2n–1
Horizontal Image Size
Leading edge
replicated pixel
Trailing edge
replicated pixels
nn–1
Y’
a
= Y
a
Y’
b
= Y
b
Y’
c
= Y
c
Y’
n–2
=
Y
n–2
Y’
n–1
=
Y
n–1
Y’
n
= Y
n
Y’
a
’ = ƒ(Y
a’
, Y
a’
, Y
b’
, Y
c
)
Y’
b’
= ƒ(Y
a’
, Y
b’
, Y
c’
, Y
d
)
Y’
n’
= ƒ(Y
n–1
, Y
n
, Y
n
, Y
n–1)
Y’
n–2’
= ƒ(Y
n–3
, Y
n–2
, Y
n–1’
, Y
n
)
Y’
n–1’
= ƒ(Y
n–2
, Y
n–1
, Y
n’
, Y
n
)
Luma (Y)
sample
Chroma (Cb/Cr)
samples