Well canvas can be pretty forgiving of low resolution images. The weave texture itself imposes a sort of mechanical version of what GF does. You can also process what you get to recast fuzzy images into brush-stroke-like polygonal shapes with sharper outlines, Photoshop has a lot of filters that can do this. In fact many pro portrait photographers who offer portraits and family shots delivered on canvas deliberately reduce sharpness this way, to simulate an oil painting.
You need to put a spin on it to prep your customers. Inform your potential customers up front of "special processing" that can turn their snapshots into large scale images with a painting-like quality. Rather than just saying we can fix your crummy pictures. And of course we all know that painting trumps mere photography.
But honestly, making big prints for John Q. Public is nothing I would ever want to do!
FWIW, the local Kinkade gallery has a street placard out in front of their store offering to do exactly this sort of thing. There's a snapshot of a little girl, then next to that the spiffed-up "oil painting" version, presumably on canvas and shown in Kinkade-esque traditional framing. So there's some market. But really, Thomas, how déclassée!
