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Seeb
October 28th, 2010, 08:57 PM
Hi,

since I don't have a xorg.conf anymore (just wasn't installed :-o) I wonder how to change the color depth to 32.

I'm using the standard xserver-xorg-video-radeon driver.

Thank you.

mcduck
October 28th, 2010, 09:26 PM
You don't. :)

There is no such thing as 32-bit colors, at least when it comes to displays. Not even when Microsoft likes to call their 24-bit color mode a "32-bit" mode.

24-bit colors give you 8 bits per color channel, totaling 16,7 million colors (2^8 * 2^8 * 2^8 = ). That's way more than what most LCD displays are able to handle (in fact most consumer-grade LCD panels are really only able to display 18-bit colors)

Pictures and graphics can have 32-bit colors, in which case the last 8 bits are used for Alpha channel (transparency). As long as out displays can't become transparent they have no need for those last 8 bits.

edit: http://en.wikipedia.org/wiki/Color_depth


32-bit color

It is generally a misnomer in regard to display color depth. While actual 32-bit color at ten to eleven bits per channel produces over 4.2 billion distinct colors, the term “32-bit color” is most often a misuse referring to 24-bit color images with an additional eight bits of non-color data (I.E.: alpha, Z or bump data), or sometimes even to plain 24-bit data.


edit 2: if it seems like you don't have enough color depth, you are probably running in 4-bit or 8-bit color mode. In that case you can fix it using xorg.conf just like before. While the file doesn't exist by default it's used if you create it.

Seeb
October 28th, 2010, 09:38 PM
Hey, thanks for your reply.

I already know that there is no visible difference for the human eye between 24 and 32 bit, but i think i need that 32 bit mode to get transparency with xcompmgr to work (see: http://ubuntuforums.org/showthread.php?t=1607992 ).

I am currently running in 24 bit mode.

I will create a xorg.conf file now and I hope, Ill be able to switch to 32 bit. Thank you :-)

Edit:
I can just "touch" the xorg.conf right? I dont have to run xorgconf, since I dont know the vsync rates and stuff from my laptop screen.

I have this now:


Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
DefaultDepth "32"
EndSection

mcduck
October 28th, 2010, 09:58 PM
Hey, thanks for your reply.

I already know that there is no visible difference for the human eye between 24 and 32 bit, but i think i need that 32 bit mode to get transparency with xcompmgr to work (see: http://ubuntuforums.org/showthread.php?t=1607992 ).

I am currently running in 24 bit mode.

I will create a xorg.conf file now and I hope, Ill be able to switch to 32 bit. Thank you :-)

Edit:
I can just "touch" the xorg.conf right? I dont have to run xorgconf, since I dont know the vsync rates and stuff from my laptop screen.

I have this now:


Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
DefaultDepth "32"
EndSection

no, I really mean that there is no 32-bit mode for your display. You can't set such mode in xorg.conf. It doesn't exist.

That's the very point of using a compositor, it composites the 32-bit graphics into 24-bit image for your display, allowing programs to use transparency.

24-bit color mode for the display is all you need, if you have problems with xcompmgr it's definitely something else than the color mode of your display.

Seeb
October 28th, 2010, 10:02 PM
Ahh, ok, I get it.

My Xserver wouldnt want to start with those settings any way :D


thanks man.