Zooming in, I saw that the issue seems to be related to subpixel rendering. You can see that the smaller version of the "Shalom" is "subpixeled to death". wrote about Infinality - the FreeType patches and configuration files that make fonts on Linux look like never before. Two years after, I'm still blown away with how good fonts look. Glancing at Windows Cleartype I fill really sorry for Windows users :) But... its doing no good to Gimp font rendering.
So I tried to disabling subpixel rendering system-wide to see if it helps - it does! Now Gimp renders fonts very good!
So the solution is to disable subpixel rendering for Gimp (and for Gimp only). Easy as it may sound it took me a while to figure out how to do it - font-config system has no generic way to make the application-specific settings. Obviously I did not want to disable it globally, since it clearly crippled the beautiful font rendering I came to love so much: kubuntu.org. On the right, subpixel rendering is disabled. Look at the difference in zoomed versions - without subpixel rendering letters look more dull and square (especially note the vertical bar of the "K" and "b" letters). Letters on the left look juicy and sharp all together - and that's hard to achieve. Usually its either "juicy but blurry" or "sharp but harsh". Infinality's way of configuring this struck the chord (for me).
Anyways, back to Gimp. After all, I found nice article in ArchLinux wiki - they have a complete article on Infinality with related issues and workarounds and it had a solution to my gimp problem. As another mailing list said, applications may support their own way for overriding font-config configuration. And in fact, gimp does support this by reading
~/.gimp-2.8/fonts.conffile. So I've placed the following into this file:
<fontconfig> <match target="font"> <edit name="rgba" mode="assign"> <const>none</const> </edit> </match> </fontconfig>(Looks like fontconfig files refer to "subpixel rendering" term just as "rgba"). Now I can enjoy rendering text in Gimp without sacrifices :)
This is the only issue with Infinality that I've encountered so far. Otherwise fonts look so so so so much better to me. If you have issues with Infinality, make sure to check the ArchLinux wiki article on the subject.