title: Install OpenCV on OS X Lion
body: <p>I'm trying to install OpenCV for the paperclip-facecrop gem but I'm having problems installing the opencv gem.</p>
  
  <p>I installed opencv with brew and I think the gem just needs to know the right path?</p>
  
  <p>Gemfile</p>
  
  <pre><code>gem "paperclip", "~&gt; 2.3"
  gem "opencv", :git =&gt; "https://github.com/ser1zw/ruby-opencv"
  gem "paperclip-facecrop"
  </code></pre>
  
  <p>.bash_profile</p>
  
  <pre><code>    export PYTHONPATH="/usr/local/lib/python2.6/site-packages/:$PYTHONPATH"
      # OS X 10.7 Lion
      # Set the compiler to GCC (instead of default LLVM) for RVM
              # For Lion, Rubies should be built using gcc rather than llvm-gcc. Since
          # /usr/bin/gcc is now linked to /usr/bin/llvm-gcc-4.2, add the following to
          # your shell's start-up file: export CC=gcc-4.2
          # (The situation with LLVM and Ruby may improve. This is as of 07-23-2011.)
      export CC=gcc-4.2
  </code></pre>
  
  <p>Console</p>
  
  <pre><code>/Users/jonathanspooner/.rvm/rubies/ruby-1.9.2-p290/bin/ruby extconf.rb 
  &gt;&gt; check require libraries...
  checking for main() in -lopencv_calib3d... yes
  checking for main() in -lopencv_contrib... yes
  checking for main() in -lopencv_core... yes
  checking for main() in -lopencv_features2d... yes
  checking for main() in -lopencv_flann... yes
  checking for main() in -lopencv_gpu... yes
  checking for main() in -lopencv_highgui... yes
  checking for main() in -lopencv_imgproc... yes
  checking for main() in -lopencv_legacy... yes
  checking for main() in -lopencv_ml... yes
  checking for main() in -lopencv_objdetect... yes
  checking for main() in -lopencv_video... yes
  checking for main() in -lstdc++... yes
  &gt;&gt; check require headers...
  checking for opencv2/core/core_c.h... yes
  checking for opencv2/core/core.hpp... yes
  checking for opencv2/imgproc/imgproc_c.h... yes
  checking for opencv2/imgproc/imgproc.hpp... yes
  checking for opencv2/video/tracking.hpp... yes
  checking for opencv2/features2d/features2d.hpp... yes
  checking for opencv2/flann/flann.hpp... yes
  checking for opencv2/calib3d/calib3d.hpp... yes
  checking for opencv2/objdetect/objdetect.hpp... yes
  checking for opencv2/legacy/compat.hpp... yes
  checking for opencv2/legacy/legacy.hpp... yes
  checking for opencv2/highgui/highgui_c.h... yes
  checking for opencv2/highgui/highgui.hpp... yes
  checking for stdarg.h... yes
  &gt;&gt; ----- optional -----
  &gt;&gt; check ffcall...
  checking for main() in -lcallback... yes
  checking for callback.h... yes
  &gt;&gt; support OpenCV::GUI::Window#set_trackbar
  creating Makefile
  
  make
  Makefile:172: warning: overriding commands for target `/Users/jonathanspooner/.rvm/gems/ruby-1.9.2-p290@woodhack/bundler/gems/ruby-opencv-1162590303e6/lib'
  Makefile:168: warning: ignoring old commands for target `/Users/jonathanspooner/.rvm/gems/ruby-1.9.2-p290@woodhack/bundler/gems/ruby-opencv-1162590303e6/lib'
  g++ -I. -I/Users/jonathanspooner/.rvm/rubies/ruby-1.9.2-p290/include/ruby-1.9.1/x86_64-darwin11.0.0 -I/Users/jonathanspooner/.rvm/rubies/ruby-1.9.2-p290/include/ruby-1.9.1/ruby/backward -I/Users/jonathanspooner/.rvm/rubies/ruby-1.9.2-p290/include/ruby-1.9.1 -I./ext/opencv -DHAVE_OPENCV2_CORE_CORE_C_H -DHAVE_OPENCV2_CORE_CORE_HPP -DHAVE_OPENCV2_IMGPROC_IMGPROC_C_H -DHAVE_OPENCV2_IMGPROC_IMGPROC_HPP -DHAVE_OPENCV2_VIDEO_TRACKING_HPP -DHAVE_OPENCV2_FEATURES2D_FEATURES2D_HPP -DHAVE_OPENCV2_FLANN_FLANN_HPP -DHAVE_OPENCV2_CALIB3D_CALIB3D_HPP -DHAVE_OPENCV2_OBJDETECT_OBJDETECT_HPP -DHAVE_OPENCV2_LEGACY_COMPAT_HPP -DHAVE_OPENCV2_LEGACY_LEGACY_HPP -DHAVE_OPENCV2_HIGHGUI_HIGHGUI_C_H -DHAVE_OPENCV2_HIGHGUI_HIGHGUI_HPP -DHAVE_STDARG_H -DHAVE_CALLBACK_H -I/usr/include -I/opt/local/include -I/usr/local/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE   -fno-common -O3 -ggdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wpointer-arith -Wwrite-strings -Wno-missing-field-initializers -Wshorten-64-to-32 -Wno-long-long  -fno-common -pipe -I./ext/opencv   -o cverror.o -c ./ext/opencv/cverror.cpp
  ./ext/opencv/cverror.cpp: In function ‘void mOpenCV::cCvError::define_ruby_class()’:
  ./ext/opencv/cverror.cpp:143: error: ‘CV_GpuCufftCallError’ was not declared in this scope
  ./ext/opencv/cverror.cpp: In function ‘void mOpenCV::cCvError::raise(cv::Exception)’:
  ./ext/opencv/cverror.cpp:157: warning: format not a string literal and no format arguments
  make: *** [cverror.o] Error 1
  </code></pre>