http://www.jianshu.com/p/ac4c4536ca3e
http://www.jianshu.com/p/016e55c25521
http://khalsa.guru/posts/16
https://ryanfb.github.io/etc/2014/11/19/installing_tesseract_training_tools_on_mac_os_x.html
https://blogs.wcode.org/2014/10/howto-install-build-and-use-opencv-macosx-10-10/
https://segmentfault.com/a/1190000003742411