require 'find'

def find_and_print(path, pattern)
  Find.find(path) do |entry|
    if File.file?(entry) and entry[pattern]
      has_transparency = `identify -format %A #{entry}`
      if has_transparency.to_s.chomp.strip == "True"
        puts "#{entry}"
      end
    end
  end
end
 
# print all the ruby files
find_and_print("/rails_app/public/images", /.+\.png$/)