Digital BW, The Print

Dear all,

Lately I have been exchanging emails with Ctein * on the subject of
rezzing-up and upsampling and resolving what Jeff Schewe and the late
Bruce Fraser have basically said: «If the native resolution of an
image fall between 180 and 480ppi, just sent the file to the printer»

After reading his emails a few times, I decided to share with you his
observations, which, IMHO, may be of interest to the members this
list. As for myself, I think I've learned a lot from his emails and
will certainly review the way I print.

"Dear Andre, 

Broadly, I agree with Schewe and Fraser. 180 PPI is a bit low for my
taste for smaller prints (up to 11 x 14). I've got pretty sharp eyes
and I can see the pixelation at that resolution. 240 PPI and above
really isn't a problem. If you're talking about larger prints, 180
would be fine. As for the high end, there's really no reason to ever
resample, unless your computer is choking on the size of the file. It
doesn't matter whether you send the printer 500 PPI, 1000 PP or even
2000 PPI; it'll simply print as much detail as it can and that's it. 

Related to that is the "base resolution" issue. That term is something
of a misnomer with modern printers. All of the "photo-quality"
printers can reproduce considerably finer detail than 300/360 PPi.
Even the Epson 2200, the least sharp printer I've tested in the past
five years, reproduced 450 PPI; the best printers I've used can
reproduce 800-1000 PPI worth of fine detail. If I have a higher
resolution file, I would never down-sample it to a mere 360/300 PPI
for output; I would just be throwing away detail. 

There are VERY subtle artifacts that turn up with "non-native" PPI's,
but I can only see them in carefully designed and very artificial test
charts and they're down near the single-pixel level. They're
completely invisible in a regular photograph. It's an entirely
ignorable effect with modern printers. 

~ pax \ Ctein" 

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It's just Ctein, no "Mr." in front of it. We're all friends, here. 

I'm glad I could be of help. Yes, there is a lot of old, obsolete
"wisdom" out there. Plus there is some accurate yet misleading testing
going on as well. Some folks use special test targets to determine the
point where the printer starts introducing artifacts into the image
and assert that that's limiting resolution of the printer. That's only
true if you're using it for scientific purposes where you need 100%
perfect fidelity of reproduction. From a photographer's point of view,
the limiting resolution is the one where throwing finer detail at the
printer doesn't give you any more detail in the print, and that's
several times finer detail than the level at which no distortions at
all occur. 

~ pax \ Ctein 

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I don't believe I wrote anything particularly embarrassing [ smile ],
so feel free to quote me. 

I read Mike's column at the link you provided, and I think he gives a
pretty good assessment of the situation. There is one important point
he didn't mention; printing to a dye-sublimation printer is different
from printing to an inkjet printer. There are good reasons to
re-sample an image to the native resolution of a continuous tone
printer like dye-sublimation, because they really do operate with a
fixed pixel pitch. There is never an advantage that I can see to
downsampling an image to the "native resolution" of an inkjet printer.
Sending less detail to the printer just to match the native resolution
will always produce a less detailed print and won't make a visible
difference in terms of odd artifacts. 

~ pax \ Ctein 


* Ctein is a photographer, master printer and scientist. He has a
double degree from Caltech in English and Physics.

Mike's column refers to Mike Chaney.