Bug 13727

Summary: radeonhd: lvds dithering not ideal.
Product: xorg Reporter: Steven Garrity <steven>
Component: Driver/radeonhdAssignee: Luc Verhaegen <lverhaegen>
Status: RESOLVED FIXED QA Contact: Xorg Project Team <xorg-team>
Severity: normal    
Priority: medium    
Version: unspecified   
Hardware: x86 (IA32)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
Artists rendition of screen-noise none

Description Steven Garrity 2007-12-18 15:17:21 UTC
When using the radeonhd driver on my Thinkpad T60p with an ATI X1400 (Fedora 8), I see slight visual noise across the entire screen. It's hardly noticeable from a distance, but when you look at large solid-color areas, or at anything close-up, it is clearly visible.

It's difficult to describe, and I can't take a screenshot since it's happening on display. The best I can describe it is that it looks like slight JPEG compression noise, or like a color dithering (though the display is set to "Millions of Colors").

I've attached a faked image from the gimp that uses a "noise" filter to attempt to give an idea of what it looks like on a solid grey background.

If I use the fglrx driver or the vesa driver, I do not see this noise.
Comment 1 Steven Garrity 2007-12-18 15:18:02 UTC
Created attachment 13196 [details]
Artists rendition of screen-noise
Comment 2 Egbert Eich 2007-12-18 15:47:53 UTC
Steven, would you please supply a log file?
Comment 3 Matthias Hopf 2007-12-19 01:40:49 UTC
Looks like 18bit panel spacial dithering. Some people like it, some don't. This will be configurable in the future (if it is this issue).
Comment 4 Luc Verhaegen 2007-12-19 06:09:44 UTC
Try our git version of the driver. This should already improve things for you.

I will add configuration of which dithering is used in time, as i have more pressing issues at the moment.

Report back with a recent version of the driver.
Comment 5 Steven Garrity 2007-12-19 14:16:50 UTC
Tried the latest git version and it looks great (just like fglrx and vesa, as far as I can tell).

Marking as FIXED - thanks.

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