Just a note, instead of encoding the picture in the full destination URL, you can encode the picture into the padding section between the URL and the Reed-Solomon section, thus permitting the use of any URL. I used this technique a long time ago on qrpixel.com but forgot to renew the domain, oops... http://web.archive.org/web/20160423015339/http://www.qrpixel... Also for information about how this works, Russ Cox did…
I'd be very glad to see it online again.