It's getting thankfully rarer these days that I get totally stumped but this one has me.

Is it possible to change colour depths within an X session? I know how to edit xorg.conf to alter the default and of course CTL + ALT + (+ or -) alters the resolution; but depth?

I even resorted to sifting through KDE's Utilities/System/Settings/Control Centre but to no avail.

BTW, is it just me all do all of those KDE headings mean the same thing?

Maybe edit xorg.conf and then ctrl+alt+backspace?

Thanks but <CTL><ALT><BACKSPACE> is the universal 'X kill' keyboard shortcut. Reminds me of the '<CTL><F4> lark in windowworld.

Edit xorg.conf to what exactly? The lists of resolutions that are stepped through, although grouped by depth, have no affect on it. Even it it did change, how would you ever know that it changed? I can't even find a way to read the current setting let alone invoke a new one.

Even Nvidia's helpful little app has nothing :-(

I can't say that I've seen any way of doing this without exiting X and changing xorg.conf manually

After diving into the KDE Control Center, then twisting and turning toward Peripherals and Display, I see that KDE seems to be designed with an understanding of what you seek. My guess is that the various depth options all must be defined correctly in xorg.conf so that KDE can grab them and display them in the drop-down list. I see only two options in that drop-down list and they are not depth related but vertical frequency related. And when I try fiddling with the additional option I get a really wacky screen. I'm not sure what else I need to do to change the depth on the fly and have those options appear in the Control Center, but the potential seems to be there.

Not to rub salt in any wounds, but modifying the color depth in Windows, at least on my NT4 box, is straightforward. Seems doing likewise in X or KDE should also be straightforward.

Yeah, I think it should be in peripherals->display but it has been forgotten. I'll pop over to kde and offer it as a suggestion.
The options in there just reflect what can be achieved by stepping through the pre-configured X resolution settings.

Of course it's always possible that it is a limitation of X. Surely not?

Please forgive the silly question, but could I ask *why* you're trying to change the depth on the fly?

I can't find any up-to-date information regarding bit-depth changes on the fly in X. I found one messageboard talking about it in 1998, who all say: "X doesn't do that!" but I feel it must have moved on least a little since then ...

- Piete.

I had trouble with the rendering in Earth3D and Dominique (the writer) told me that it only works in 24 or 32 bit colour depth environments. I was sure mine runs at 24 bit (xorg default) but had no way to confirm it in KDE and no way to change it other than editing the default in xorg.conf