Add this line to your Gemfile:

gem 'cal-screenshot-resize'

And then execute:

 $ bundle

Or install it yourself as:

 $ gem install cal-screenshot-resize

require "screenshot/resize"

Screenshot::Resize::screenshot_with_scale(:scale => 0.5)

:scale => 0.5 mean that screenshot will be 2 times smaller than original if you whant to use directly screenshot_with_scale add include Screenshot::Resize to your code

Bug reports and pull requests are welcome on GitHub at https://github.com/ark-konopacki/cal-screenshot-resize.