Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, BKPhoto@a... wrote:
> 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
> 

Thanks, Bill.

Well it's interesting that you do see some differences.  I'd be hard pressed
to speculate why -- especially seeing differences with a loupe.  All the 
dithering (do you get a choice with IJC?) is the same and all 16-bit for both
products.   Although we both started with gimp-print the 4000 support was
done independently.

For QTR the difference might be that Photoshop has a more sophisticated
algorithm for converting to 8 bit.  That might be worth doing.

Roy