AMD Geode SC1201 - Manual (Page 328)

328 AMD Geode™ SC1200/SC1201 Processor Data Book
Video Processor Module 32579B
Figure 7-12. Color Key and Alpha Blending Logic
Color register
enabled for this
window
“Graphics 2
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 value 3
matches
normal color
key
Yes
No
Blend graphics
values and video
values using the
alpha value for
this window
Pixel value 3
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 inside 1
alpha window
COLOR_CHROMA
_SEL = 1
COLOR_CHROMA
_SEL = 1