Full Use Case:
I would like to generate a QR image that can then be merged into a document with A5 Documents app. I need to deliver a digital certificate via email that needs to have a QR code on it.  Then the customer can print that out and redeem that certificate at the local shop where the local shop needs to scan the QR code with any QR scanning free app on the iPhone/Android to redeem it which will link to a custom web script development team will write to process that redeem back into Salesforce.

With A5 Documents, you can just merge a URL of the image then you just need a URL. Google has various google chart API’s that you can use to generate charts pretty easy with some data.  Here is an example of them generating a simple QR code which is just a URL: https://chart.googleapis.com/chart?chs=200×200&cht=qr&chl=https://ramseysolutions.com.

-How to Build Process:
You can create a formula field in Salesforce with Image() function to display a QR code for a record for example.  Or create a formula field that will create the URL for generating the QR code then merge that URL as the image in the document template.  And then you got a QR code merging on the document without any code or actual image needing to be saved.
A QR code basically is just a URL and when you scan it it accesses the url, so you just put a variable in the url such as http://a5-apps.com/qrscript.php?orderid=a0A0L00000JfKPN  and the web script gets the ordered and then can update Salesforce matching on that ID.