Reader [Nikolaus] decided that instead of using an existing image based bar code decoder, he would write his own. Using the Processing language he created a scanner that parsed the black and white pattern when a bar code was centered on the image. His code then parsed that data and compared it with the initializing character to provide a reference. Currently his scanner supports three character sets of the Code 128 encoding, and provided his complete code so that others could add as they see fit. He admits that the code is a bit messy due to the lengthy character tables, but very straight forward.
What hardware does this use to do the scanning?.
I believe this uses webcam. From the code that is what it looks like.
The “Processing” “language” (quotes intentional) should not be confused with Arduino (which I usually hate; but sometimes-not [0.16″ header spacing]). I kind of like Processing, and this is a nice example.