32-bit colours

[Agent007]

Hi!

Am using RedHat Linux 7.2, How can i force Xserver use 32bit colors instead of 16bit or 24bit. the graphics card is a Riva TnT with 16MB RAM. Supports 16bit and 32 bit colours NOT 24bit.

thanks,
Agent007

[JimH]

Under X the value 32 is not a valid color depth. That said under X a setting of 24 is 32. ;D

From the X docs:
"depth means the number of bits in a pixel that are actually use to determine the pixel colour. 32 is not a valid depth value. Most hardware that uses 32 bits per pixel only uses 24 of them to hold the colour information, which means that the colour depth is 24, not 32."

This information is for using the open source nvidia driver included with XFree86. If you are using the closed source binary only drivers from nvidia this may be different. Try looking at the docs nvidia provides for their drivers. I don't use nvidia based graphics cards. Some one else on the board who uses the binsry nvidia drivers might know the answer.

Jim H

[Braveo]

To add to his post:

When you have 32-bit color depth, what you really have is 24-bit color depth with extra information added in.

You have 4 channels, RGBA
Red
Green
Blue
Alpha

RGB is the actual color depth, while Alpha is nothing more than a description of how to mask that particular pixel when it's overlaid with something else.

This allows for transparency effects, irregular shapes, etc.

[Agent007]

Thanks for ur help guys!! I've been searching all over help, but was'nt successful until now. This forum is cool!!

rgds,
Agent007