I'd like to get some different thoughts on what is acceptable for printing. 4608 x 3456 is the native size of my files, un-cropped. My rule of thumb is that anything over 24 x 18, I switch to canvas wraps, instead of doing framed prints behind glass. I'll resize/resample my images (in photoshop) to hit 150 ppi. I use CGProprints, and this is what they print their canvases at. Anything at or below that print size I resize/resample to hit at least 192 ppi (the native ppi of the file at that size, if I don't crop any pixels). I get that some printers request 250-300 ppi for their files, but will I really notice a difference, given that I won't have my nose up to the print. Do those printers take into account viewing distance. Is there a ppi and viewing distance calculator available online? I've had one my 4/3 images used before on a billboard, and moving a 75 mph the less than 30 ppi (pretty sure it was) print looked spectacular. Thoughts? What s acceptable for you?