how to check if a photo will be ok as a big print or canvas?

[fletcher11]

I have been searching for a while on google for a way of checking if a photo would be ok on a canvas or a bigish print and it just kept coming up with sites and not saying anything about it. so could someone give me an idea how i would go about checking this before i ordered any?

 

[POAH]

because canvas is rotton for definition you can get away with quite a lot of interpolation before you'd see any artifacts on a canvas