Creating a barcode is as simple as calling the classes
   static draw() method after including
   Image/Barcode.php.
  
   The method has four parameters: The first is the string that shall be
   converted into barcode representation. The second parameter determines
   which driver/type should be used; it is one of:
   Code39, code128,
   ean13, int25,
   postnet or upca.
  
The case difference between
Code39andcode128has no reason and makes no sense, but is kept because of backward compatibility.
   The third parameter of draw() determines
   the type of the image that is generated; one of
   jpg, png and
   gif.
  
   By default, the image generated by the barcode driver is directly
   output to the browser. If you do not want this, pass
   false as fourth parameter and
   draw() will return the GD image resource
   object; allowing you to do further things with it.