Digital BW, The Print

> From: Paul Roark <paul.roark@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Thu, 20 Oct 2005 10:00:15 -0700
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: RE: [Digital BW] ICC v. Transfer Function in Epson driver
> 
> I've printed several samples this morning to further explore the flat
> 95-100% print separation issue.  Consistent with what Roy noted, I've found
> QTR Create ICC 3.2.1 does not always work with un-even increments.  On the
> other hand, if there are 1% increments from 100 - 95%, then 5% to 75% and
> then 10% steps on the rest of the scale, the print is about the same as if
> there are 5% increments all the way.  In both cases there are steps in the
> 95 - 100% where the "lighter" input step is printed darker than the adjacent
> "darker" input step.  On the other hand, they are all so close that this
> "posterization" could be random printing artifacts and X-Rite reading
> errors, and there is no visible separation or "posterization."
> 
> Of more relevance, I'm not generating enough 95% - 100% separation with the
> Create ICC approach to have visual separation in that region.  For example,
> looking just at the case where the input text file has 5% steps over the
> entire scale, the 100% - 95% separation or difference is Lab L 0.46.  This
> is with the C86 and MIS EZ inks on EEM.  (PS CS2, Print with Preview, Let PS
> Determine Colors, Perceptual, and Black Point Compensation on)  The driver
> with no ICC loaded has a 100% - 95% separation of L 2.39, with every 1% step
> being measurably separated.  For comparison, the 2400 with Eboni loaded, in
> the ABW mode with neutral and normal tone settings (and no ICC loaded in the
> PwP) has a 100% - 95% separation of L 2.30.

You should compare separation not with Epson ABW but with an Epson colour
managed print.  The Adv B&W print is the equivalent of a linearised but not
profiled print.  Epson ABW is missing this management and that's why using
QTR Create ICC can fill the gap in Epson ABW workflow.  That's not to say
the luminance managed approach is for you but it puts you on an even keel
with the colour community.


> 
> The gammas generated by these printing approaches is different, and that, of
> course, would have some effect on the 100% - 95% separation.  Looking at the
> 50% density as a relative measure of gamma, the 2400 (EEM, ABW, neutral,
> normal tone) and C86 EZ (Epson Color Controls gamma 2.2, Contrast -10) have
> essentially the same L 58 50% density.  The C86 with the ICC has a 50%
> density of L 54.

More where you'd expect it.
> 
> My main concern is that a visually un-separated 95 - 100% "wastes" limited
> grayscale by essentially clipping the darkest 5%.  It is true, of course,
> that with 16 bit files this is much more tolerable than is was with 8 bits
> and a barely sufficient 256 total steps.
> 
> I have noticed that Epson drivers in printers aimed only at the color market
> often if not typically clipped the darkest 5% also, as did some samples of
> B&W output that were printed by Image Print on a 9600.
> 
> Additionally, without a custom dot gain curve, my monitor (profiled with
> SpyderPro 2) also has no visual 100% - 95% separation.  However, I'd thought
> in an earlier thread many said that they do have such separation.  So, I'd
> assumed my modestly priced CRT and video board were largely responsible for
> the lack of deep shadow separation.
> 
> On LCD displays I have on other computers in my house, still modestly
> priced, the 95% - 100% steps are separated.
> 
> In short, my "wasting grayscale" concerns aside, the ICC approach I'm
> getting -- i.e., clipped darkest 5% -- matches my old CRT monitor quite
> well.
> 
> On the other hand, the 2400 ABW and C86 prints (close to the old standards
> I'd used from the Piezo days forward) match my LCDs better.  If matching the
> monitor is the issue, I'm not sure matching an older CRT is a worthwhile
> goal.  I suspect LCDs more like my newer, entry level Princeton displays are
> more typical of the larger market I'm most interested in facilitating.
> 
> What kind of 100% - 95% print separation (Lab L differences) are others
> seeing with the Create ICC approach?  Is it just my system?
> 
>
I'll post some test results when I switch over to MK ink.