Red Hat Bugzilla – Bug 194143
horizontal ghosting with Metacity AIGLX compositing
Last modified: 2014-06-18 05:08:17 EDT
Description of problem:
When AIGLX and Metacity compositing are enabled, I'm seeing a slight horizontal
ghosting in all color channels. Assuming a white background, any non-white
pixel is slightly faded out, and a very pale "ghost" of that pixel appears
offset one pixel to the right of the original.
The impression is as though the screen pixel grid were slightly offset from the
pixels that are to be displayed, so that what I'm actually seeing is the effect
of some kind of anti-aliasing. What should be crisp vertical lines end up being
a bit blurred. The entire screen therefore ends up looking a bit fuzzy. This
is especially noticeable with text, though it affects *all* pixels, not just
This is difficult to describe; I'll attach some test images that should make the
problem more clear.
Version-Release number of selected component (if applicable):
System is Fedora Core 5 with serveral components installed from the FC5 AIGLX
RPM repository, including:
Consistently occurs at all times when Metacity compositing manager is enabled
(gconf "/apps/metacity/general/compositing_manager" set to true). Does not
occur if Metacity compositing manager is disabled.
Steps to Reproduce:
1. Start up your favorite drawing program, such as The GIMP.
2. Paint a single black pixel on a white background.
3. Use "xmag" to zoom in on that black pixel.
4. Examine the color of the black pixel as well as the pixel just to it right.
The single black pixel on a white background appears as color #202020. The
pixel immediately to the right has color ##dfdfdf.
The single black pixel should have color #000000. The pixel immediately to the
right has color ##ffffff.
Hardware is a ThinkPad X40 with Intel 82852/855GM Integrated Graphics Device.
Created attachment 130549 [details]
test image: four crosses on white background, no antialiasing
Created attachment 130550 [details]
buggy result, magnified; note ghosting to the right of each cross
Closing bugs related to the metacity compositor, since we no longer develop it.