require 'zxing'

 # You can decode a URL...
 ZXing.decode 'http://2d-code.co.uk/images/bbc-logo-in-qr-code.gif'

 # ... or a file path...
 ZXing.decode '/Users/ecin/qrcode.png'

 # ... or a File object...
 ZXing.decode File.open('qrcode.png')

 # ... or anything that returns a URL or file path when #path or #to_s 
 # is called on it.
 class Image
 attr_reader :path
 def initialize(path); @path = path end
 end

 image = Image.new('qrcode.png')
 ZXing.decode image

 # #decode returns nil if it can't decode the image.
 ZXing.decode 'image_without_a_code.png'
 # => nil

 # #decode! will raise an error if it can't decode the image.
 ZXing.decode! 'image_without_a_code.png'
 # => NativeException

 # Feel free to include ZXing to shorten the call.
 include ZXing

 decode 'qrcode.png'

 require 'zxing/decodable'

 class File
 include Decodable
 end

 file = File.open('qrcode.png')
 file.decode