GraphicsMagick is a replacement for ImageMagick. Now www-apps/redmine depends only on media-gfx/imagemagick.
Sorry about the mass reassignment, but this undertaking really shouldn't burden bug-wranglers further.
redmine depends on rmagick, not ImageMagick.
and rmagick2 has no support with GraphicsMagick. 
 http://rmagick.rubyforge.org/ Which version of RMagick is right for me?