gem install rmagick でエラー

rmagickインストール時にエラー

gemでインストール

$ gem install rmagick

Building native extensions. This could take a while...
ERROR: Error installing rmagick:
ERROR: Failed to build gem native extension.

   /usr/local/Cellar/ruby/1.9.3-p286/bin/ruby extconf.rb

checking for Ruby version >= 1.8.5... yes
extconf.rb:128: Use RbConfig instead of obsolete and deprecated Config.
checking for /usr/bin/clang... yes
checking for Magick-config... no
Can't install RMagick 2.13.1. Can't find Magick-config in >/usr/local/bin:/usr/local/Cellar/ruby/1.9.3->p286/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin

*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.

Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/usr/local/Cellar/ruby/1.9.3-p286/bin/ruby

Gem files will remain installed in /usr/local/Cellar/ruby/1.9.3->p286/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1 for inspection.
Results logged to /usr/local/Cellar/ruby/1.9.3->p286/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1/ext/RMagick/gem_make.out

Magick-configがないということなので、ImageMagickをhomebrewでインストール

homebrewでimagemagickインストール

$ brew install imagemagick

gemでrmagickを再度インストール

$ gem install rmagick

Building native extensions. This could take a while...
Successfully installed rmagick-2.13.1
1 gem installed

すばらしい。