Digital BW, The Print

Roy-

I pulled test prints through IJC/OPM and QRT. Same grayscale file (12x15 inch 
image area). One print at 16-bit, the other at 8-bit. Tests were made with a 
4000 using UC, on Epson Enhanced Matt roll paper.

There are obvious differences between the RIP's, of course. The supplied 
IJC/OPM profile did a better job of matching the on-screen image contrast and 
density (I use Dot Gain 20% as my default working gray space). By adjusting the 
QRT image using Ink Limit and Gamma, I was able to marginalize the differences. 
The colorcasts provided by the two RIP's are also different enough to 
influence my judgment.

I cannot see any significant differences in the prints that I can 
subjectively attribute to bit depth. There are differences, but very subtle. With IJC/OPM 
the 16-bit file printed with a very small increase in contrast. You can see 
this under a loupe. At normal viewing distance, the impression is that the 
print is a bit sharper and slightly darker, which is to be expected. These are 
small differences, but the kind that I learned to appreciate through many years 
of printing in the wet darkroom.

With QTR I see the opposite. The 8-bit file prints with slightly less density 
and a bit more contrast. In my opinion, the 8-bit file is a better print, for 
the same basic (and subjective) reasons I like the IJC/OPM 16-bit print. I 
used the "cool Selenium" profile, by the way.

I'm very interested to know what you make of this. My initial thinking is 
that each RIP is doing its best work the way it was designed: IJC/OPM with 16-bit 
and QTR with 8-bit.



Bill Kennedy
Associate Professor of Photocommunications
St. Edward's University
512/448-8680


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