[Bug 306251] New: Font anti-aliasing sub-pixel defect in GIMP 2.8.x with KDE

[Tyson Tan]

https://bugs.kde.org/show_bug.cgi?id=306251

            Bug ID: 306251
          Severity: minor
               URL: https://bugzilla.gnome.org/show_bug.cgi?id=683330
           Version: unspecified
          Priority: NOR
          Assignee: unassigned-bugs at kde.org
           Summary: Font anti-aliasing sub-pixel defect in GIMP 2.8.x with
                    KDE
    Classification: Unclassified
                OS: Linux
          Reporter: extvia at gmail.com
          Hardware: Other
            Status: UNCONFIRMED
         Component: general
           Product: systemsettings

Summary:
In GIMP 2.8.x on a system with KDE installed, after making change to KDE's font
anti-alias settings, inserting white texts with anti-aliasing option over
colorful background will produce greenish sub-pixel defect around the texts.
Such defect remains after you flatten the image and will be saved in the
document.

I don't know if this is a GIMP bug itself, but since the trigger and workaround
is within KDE System Settings, I think I should report this problem here as
well.

Reproducible: Always

Steps to Reproduce:
1. Ubuntu 12.04.1 LTS with KDE 4.8.5 from Kubuntu PPA installed.
2. Either log in Unity or KDE desktop.
3. In KDE System Settings -> Application Appearance -> Fonts -> Use
anti-aliasing -> Enabled -> Configure -> Use Sub-Pixel Rendering, Hinting Type
= None
4. Start GIMP, make a red pure background.
5. Insert some white texts over the red background, make sure antialiasing is
on.
6. Notice greenish defect around the texts.
7. Select the texts, turn antialiasing off, those defect will disappear.
Actual Results:  
The sub-pixels are always greenish unless the texts are black.

Expected Results:  
The sub-pixels should be blended with the background color.

Workaround:
KDE System Settings -> Application Appearance -> Fonts -> Use anti-aliasing ->
Enabled -> Configure -> Uncheck everything

You may apply this workaround when GIMP is running, the effect will show
immediately when you select the defect texts in GIMP, then turn antialias off
and back on.

Sometimes such defect won't show up, however I've been plagued by this problem
since the day GIMP 2.8 is out. I've encountered such defect on the following
configurations more than a few times. On Ubuntu 12.04.1 + KDE 4.8.5 + GIMP
2.8.2 this problem show up everytime after I changed KDE font anti-alias
settings.

Ubuntu 12.04 + KDE 4.8.4 + GIMP 2.8.0
Ubuntu 12.04 + KDE 4.8.4 + GIMP 2.8.2
Ubuntu 12.04 + KDE 4.8.5 + GIMP 2.8.2
Ubuntu 12.04 + KDE 4.9.0 + GIMP 2.8.0
Ubuntu 12.04 + KDE 4.9.0 + GIMP 2.8.2
Ubuntu 12.04.1 + KDE 4.8.5 + GIMP 2.8.2

All of them have QT 4.8.2 (libqt libraries) installed.

-- 
You are receiving this mail because:
You are the assignee for the bug.