Figure 7-12. Color Key And Alpha Blending Logic - AMD Geode SC3200 Data Book

32581C
Yes
Use selected cur-
sor color for pixel
Yes
Use graphics
value for this pixel
Blend graphics
values and video
No
values using the
alpha value for
this window
Replace the value
Yes
with the color
register value
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]).
324
Start
Cursor color
key matches
graphics value
No
Pixel outside
the video
window
No
1
Pixel inside
No
alpha window
Yes
3
Pixel value
matches
normal color
key
Yes
Color register
enabled for this
window
No
Yes
COLOR_CHROMA
_SEL = 1
No
Use video value Use graphics
for this pixel value for this pixel

Figure 7-12. Color Key and Alpha Blending Logic

2
"Graphics
Yes
inside Video"
is enabled
No
3
Pixel value
Yes
matches
normal color
key
No
COLOR_CHROMA
_SEL = 1
Yes
No
Use video value
for this pixel
AMD Geode™ SC3200 Processor Data Book
Video Processor Module
Yes
COLOR_CHROMA
_SEL = 1
No
Use graphics
value for this pixel