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Best view with:
IE 4.0 or higher
Netscape 4.6
16 bits color
800x600
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I have a problem about color depth. Now, I am using Red Hat 6.0 + KDE, but every time
when I start KDE, it always runs at 8 bit (256 colors) mode, I tried 'Ctrl+Alt+'+' ' under
KDE, but it doens't work, I want to change color depth, like 16 bits or 32 bits, how
can I change it? by the way, my video card is G200 SD 8MB. any help would be fine, thanks
a lot.
Answer:
Check your XF86Config file. It's automatically created by whatever
program you use to setup X. Can't say about Red Hat, but with
Slackware, it's /etc/XF86Config
Down near the bottom of the file, you'll see some lines like these from
my own system:
Section
"Screen"
Driver
"accel"
Device "ATI Graphics Xpression with Mach64 CT
(264CT)"
Monitor "TTX
7450A"
Subsection
"Display"
Depth
16
Modes "800x600" "640x480"
"1024x768"
ViewPort 0
0
Virtual 1296
800
EndSubsection
Subsection
"Display"
Depth
8
Modes "800x600" "640x480"
"1024x768"
ViewPort 0
0
Virtual 1296
800
EndSubsection
Subsection
"Display"
Depth
24
Modes "800x600"
"640x480"
ViewPort 0
0
Virtual 1088
640
EndSubsection
Subsection
"Display"
Depth
32
Modes "800x600"
"640x480"
ViewPort 0
0
Virtual 816
640
EndSubsection
EndSection
XFree86 will start in the first mode it reads, unless you tell it to use another on the
command line. Normally 8 bit depth is the first, but I've edited my file manually so that
16 bit is my default, and it starts off in 800 x 600 mode.
Note the virtual desktop sizes I've selected. These are limited by the ammount of memory
your video card has. Mine only has 2 megs, so with 8 megs, you shouldn't have much of a
problem.
Here's how to figure out the maximums you can use.
Take the ammount of video memory, 8 megs = 8,388,608
Divide by 2 for 16 bit depth, 3 for 24 bit, or 4 for 32 bit. This gives you the maximum
number of pixels you can have on the virtual desktop. Next, take the maximum physical
screen width you'll be using, and add 256 to this number. This is so that you can use
video memory as a
cache, and makes for somewhat faster operation.
I don't have enough video memory to use any caching in 32 bit mode, but
in the other modes I do.
Ok, now suppose you want to use 32 bit mode with a 1024 x 768 physical screen. Here's how
the numbers work out.
8,388,608 / 4 = 2,097,152 pixels maximum
1024 + 256 = 1280
2,097,152 / 1280 = 1638
So you could have a virtual desktop 1280 wide by 1632 tall. Note that both numbers must be
an exact multiple of 16. You could specify 1280 x 1638 in the file, but X will actually
use 1280 x 1632.
Now that virtual desktop is not the normally accepted shape, but there's nothing wrong
with using it if you want to.
Something more normal might be 1664x1248 or 1648x1264, both close to the normal 4:3 aspect
ratio.
Now, if you'ld like to use the 16:9 aspect ratio of the new HDTV, something like 1920x1088
or 1936x1072 will get you close.
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