title: How to read a barcode from an image
body: <p>I'm seeking a library, technique or advice on how to read an <a href="http://en.wikipedia.org/wiki/EAN-13" rel="noreferrer">EAN-13</a> barcode from an image (including <a href="http://en.wikipedia.org/wiki/ISBN#EAN_format_used_in_barcodes.2C_and_upgrading" rel="noreferrer">ISBN</a>,and <a href="http://en.wikipedia.org/wiki/ISSN" rel="noreferrer">ISSN</a> encodings).
  The image would come from a mobile phone or webcam, so resolution may be quite poor and not well aligned.</p>
  
  <p>I'm specifically interested in something that could be used from ruby on rails, but answers for other languages are welcome. Open Source solutions preferred.</p>
  
  <p>Leading solutions to date:</p>
  
  <ol>
  <li><a href="http://zbar.sourceforge.net/" rel="noreferrer">ZBar</a> (previously known as Zebra - h/t @bgbg, @Natim) - implemented in C with interfaces for Python, Perl, and C++</li>
  <li><a href="http://code.google.com/p/zxing/" rel="noreferrer">ZXing</a> (h/t @codr) - implemented in Java (J2SE and Android) with other modules/ports in varying states of development (JavaME, C#, C++, JRuby, RIM, iPhone/Objective C)</li>
  </ol>