Sat 16-Jun-12 12:07 AM | edited Sat 16-Jun-12 12:08 AM by barrywesthead
>Biggest will be 16x20 and viewing will probably be a few feet >head on. > At this size any 12mp (and even smaller) image will produce an excellent print.
You can upsize the file to 300dpi if you wish but it is not necessary. Just send the cropped file at 5:4 aspect ratio to the printer and specify the desired print size. If you prefer to upsize aftermarket plug-in are better that Photoshop's resize but at 16x20 it is not necessary.
Let me know if you would like more technical details on perceived resolution, print size and viewing distance and I can send you some links.