Reading Barcodes from Images/PDFs

Has anyone had any success reading barcodes from PDFs or images in a Cache/IRIS application? I've been looking at some possible solutions for this, including the open source ZXing libraries. I know we have the ability to create them in Zen and Intersystems Reports, but as far as I know, there's nothing built in to actually read data from a barcode. If anyone has suggestions on how to go about this, I'd love to hear them.

In our specific case, we print reports with a Code 128 barcode on them. We're an ERP solution, so it might be things like a proof-of-delivery or a price quote that needs to be signed off on, or a form that needs filled out. Once it's signed, we want to be able to scan the document read the barcode and upload it in a way that's associated with the order number that's encoded in that barcode.

For the past 20 years or so, we've had a Windows-based application to do this, but now we're looking at moving this functionality to run on our Red Hat server instead.