by Joseph Linaschke
I just finished creating a series of eight files to make 20 × 30 prints for a gallery show. These are B&W printed on metal, ordered through BayPhoto. I had previously created some color prints on metal that were 30 × 45, which came out very good but on close inspection, could have been higher resolution. For that job it was fine because the prints were all destined to be mounted high on a wall, so closest viewing of several feet, but for my gallery show I wanted these to look great from just a few inches away.
I spoke to BayPhoto tech support, and they suggested 240 to 300 dpi for the prints. Whoah… at 300 dpi, that's 9,000 × 6,000 pixels. That's 54 megapixels! Crap, I'm shooting with a Canon 1Ds Mk III and 5D Mk II; those are only 21 megapixels. Sounded like some upscaling was in order. I'll get into the techniques used for that in another post — after I see the printed results!
But does it matter?
This brought up a really good question that so far, no one has been able to answer with any authority. I may have to take some time and money at some point and do some really good comprehensive tests, but the question is, does it matter? Does it really benefit the final print to upscale in software to produce a 300dpi file instead of letting the printer do the interpolation itself? Maybe someone here has tested this, and if so let me know. Obviously if you have a 54 megapixel file to start with, that's best, but is there a benefit to adding the pixels in software vs letting the printer fill in the gaps itself? If so, should you scale all the way to 300 dpi? Or should you only go to 240? If your target is 300, and let's say that means scaling your photo 156%, would it be better to just scale to 150% for a more even scale and be a little under 300 dpi? Or scale to 200% and be over 300 dpi?
These are the questions I'd like to discuss here.