334 AMD Geode™ SC2200 Processor Data Book
Video Processor Module
32580B
Figure 7-12. Color Key and Alpha Blending Logic
Color register
enabled for this
window
“Graphics2
inside Video”
is enabled
Cursor color
key matches
graphics value
Pixel outside
the video
window
No
Yes
Use selected cur-
sor color for pixel
No
No
Pixel value3
matches
normal color
key
Yes
No
Blend graphics
values and video
values using the
alpha value for
this window
Pixel value3
matches
normal color
key
No
Use graphics
value for this pixel
Yes
Yes
Replace the value
with the color
register value
Yes
Start
Notes:
1) Alpha window should not be placed outside of the video window.
2) “Graphics inside Video” is enabled via bit GFX_INS_VIDEO in the Video De-interlacing and Alpha Control register
(F4BAR0+Memory Offset 4Ch[8]).
3) The “Pixel Value” refers to either the Video value or the Graphics value, depending on the setting of bit COLOR_CHROMA_SEL
in the Display Configuration register (F4BAR0+Memory Offset 04h[20]).
Yes
Use graphics
value for this pixel
Use video value
for this pixel
Yes
COLOR_CHROMA
_SEL = 1
No
No
No
Yes
Use graphics
value for this pixel
Use video value
for this pixel
No
Yes
Yes
No
Pixel inside1
alpha window
COLOR_CHROMA
_SEL = 1
COLOR_CHROMA
_SEL = 1