I briefly looked and here are my suggestions which make this vote conditional:
- Image_QRCode::makeCode() needs heavy refactoring
- @access tags are redundant
- all your set*() methods in (Image_QRCode) could be public and "return $this;" (to provide a fluent interface)
- "data" and "image" directories should be on the top level like "doc" (but anyway, kudos for a complete package.xml)
- your API version is to high
- unit tests that cover the current feature set are needed
I look forward to this code in PEAR!