16bpp and 8bpp uxa output broken...

Thomas Richter
2013-11-03T23:56:36Z

Hi Daniel, dear intel experts,

just another note: I just switched the default depth from 24 to 16 bit
by adding a "DefaultDepth" into
the screen section of X11. Strangely enough, that gives much *less*
banding than the 24bpp output????

Anyhow, 16bpp breaks the gdm login, and 8bpp breaks almost everything.
Strangely, if I switch from uxa
to sna, gdm is fine and the graphics is much smoother (less banding)
than with 24bpp output.

Greetings,
Thomas

P.S.: Strangely enough, with the 24bpp output, I can clearly count 64
distinct grey levels corresponding to
the 6bpp panel (I assume), with 16bpp output, I get a somewhat more
irregular banding (probably because
green has one bit more), though the desktop background is very smooth.
The same image, when viewed
by eog, shows banding. Thus, I suppose, that the desktop renderer
applies some kind of dithering while
eog does not. Wierd.