GitHub User: dcb-ror
There seems to be a [BUG] with RMagick and ruby 1.9.2 when trying to resize... I finall found the solution here if you still want to use Rmagick...
However, I found it much easier to just replace RMagick with MiniMagick and everything works great. MiniMagick uses less system resources too.
I having an issue trying to get the (:thumb) part to work. I think it has to do with RMagick and ImageMagick because its that steps that breaks on me.
I've followed the steps exactly, the only thing i couldnt do with the steps is install ImageMagick. I followed these instructions http://www.imagemagick.org/script/install-source.php?ImageMagick=9s6tlikqbn5eb0u0spg5o38sa4#unix
The error I'm getting http://pastie.org/1564737