Digital BW, The Print

Paul,

I just measured a 100-95% Lab L difference of 0.77 using a 2400 (MK)  
ABW, neutral, default settings printed on Hahnemuhle PR BW without an  
icc profile (no color management) versus 2.18 with a create-icc  
profile in PwP print space (perceptual, BPC checked).

Carl

On Oct 20, 2005, at 1:00 PM, Paul Roark wrote:

> 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.
>
> 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.
>
> 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?
>
> Paul
> www.PaulRoark.com



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