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 a good article on it, calculating using the R-S section as well: https://research.swtch.com/qart