# app/controllers/application_controller.rb
class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  protect_from_forgery with: :exception

  # http://stackoverflow.com/questions/32133648/rails-test-against-and-handle-actioncontrollerinvalidauthenticitytoken/32135194#32135194
  rescue_from ActionController::InvalidAuthenticityToken,
    with: :rescue_from_invalid_authenticity_token

  protected

  def rescue_from_invalid_authenticity_token(exception)
    render layout: true, text: 'document expired'
  end
end

# process each image in current folder:
Dir['*.jpg'].sort.each_slice(6).each_with_index do |names, i|
  print "#{i}\r"
  system %Q|montage #{names.join ' '} -tile 3x2 -geometry 638x538+1+1 -background black out/#{'%04d' % i}.jpg|
end; puts ''