Image processing (template matching) which can be used in calabash tests

If you don't have brew tool it can be installed with:
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

After brew installed we can install Open_CV:
$ brew tap homebrew/science
$ brew info opencv
$ brew install opencv
Default installation folder of OpenCV is: /usr/local/Cellar/opencv/installed_version/

And since we don't have plans to use python we can ignore warning about it

Ruby library for OpenCV can be installed with:
$ gem install ruby-opencv -- --with-opencv-dir=<path_to_opencvdir> (from previous step)
Like if you have:
==> Summary /usr/local/Cellar/opencv/2.4.12_2: 261 files, 35.6M
command will be:
$ gem install ruby-opencv -- --with-opencv-dir="/usr/local/Cellar/opencv/2.4.12_2"

Lib with methods avalable as a gem $ gem install cal-ios-image-proc

(Optional)For Ruby I suggest to use rbenv. For installation follow steps described under: https://github.com/rbenv/rbenv#homebrew-on-mac-os-x

At least tiff and png formats supported.
Please be careful with taking screenshot (best option is take it with calabash screenshot method).
For example: from Xcode for iPhone 6s screenshot resolution is 562×1000 but on calabash it is 750×1334 as a result template taken from Xcode screenshot cannot be found in calabash