Uploading and displaying BLOB image files is not an issue - that works perfectly. However, I need code to enable me to download the BLOB data as a stand-alone viewable jpg file.
Well, that depends on how you stored it in the first place. If you used 64Encoding, then, just 64Decode it.
If it was really stored as a JPG file, then just put the contents out to a file and make a link to it.
Perhaps you should let us know how you stored it.
If you can display the BLOB as an image, you just need to use the same code but also send download headers. Add something like this BEFORE sending any other content:
header('Content-Disposition: attachment; filename="yourimagename.jpg"');