Instalando RMagick no MacOSX
Passo 1 - Instalar MacPorts;
Passo 2 - Instalar ImageMagick e delegar as bibliotecas;
sudo port install tiff -macosx imagemagick +q8 +gs +wmf
Passo 3 - Instalar RMagick
sudo gem install rmagick
Passo 4 - Usar :D
Fonte: http://rmagick.rubyforge.org/install-osx.html
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