Digital BW, The Print

Clayton,
   Though I don't question at all what you see, that is very
strange. Are you perhaps relinearizing for the different 
papers?  If so, then the same  values in an image may be 
printing different numeric values ?  Then you could run 
into dot size crossovers or strangeness in the dither.

I have usually found (with two different model printers) the 
lightest steps to be problematic with darker inks
in that the dither patterns were uneven and very subject
to fine banding. (That said I recently tried a 2880 BO 
print and it looked just fine).

If you print a 1 or 2% step wedge instead of 5% you can
see all kinds abrubt changes in the patterns. Maybe
what you are seeing, particularly when closely examing
a small area of detail,  is the effect of moving differently
through these dither variations.

On older versions of QTR I tried different dithers (using
4 inks)  and got many wierd artifacts. Never with
ordered or Adaptive Hybrid. The gimp-print
release notes mention finding/fixing bugs in the dither
code for Eventone. I don't know whether these fixes
exist in the later versions of QTR (which are not based
on the latest bleeding egde gimp). So, perhaps 
small changes in values can throw wierd artifacts.

Otherwise, I can't imagine how dot gain differences
or contrast would give an apparent change in the
dither patterns. Very strange.

Costa



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Clayton Jones" <cj@c...> wrote:
> Tony,
> 
> Well, this is plain weird. On some papers a dither that's marginally
> better on one paper and significantly better on another is worse on
> another.  On PR some fine details are dramatically better while the
> clouds are worse.  On Aurora, one area of fine detail is significantly
> better and another is dramatically worse.  Strange strange.
> 
> >I too have been playing around with QTR curves trying to duplicate 
> >the "BO" look with Entrada Natural, Red River Aurora Art, and EEM 
> >papers.  Mainly because QTR gives me the option to use the 
> >different dithering and 2880 dpi.  
> 
> Ahh, so you know what I'm going through.  Are you finding the same
> mixed results?
> 
> 
> >Anyway, I love QTR, but STILL have not been able to get a curve 
> >that has the "luminosity" of true BO prints.  I've gotten close, 
> >but no cigar yet.  
> 
> My curve is getting close (I'm attempting to match the ramp I get from
> the 2200 driver and it's working, I'm almost there).  I have good
> luminance, but am having trouble getting the same good dmax.  That
> dark end is really tricky.
> 
> I'm going to continue experimenting with it, but over all I'm
> disappointed because it's so inconsistent.   I've gotten this far, so
> I should at least perfect the curve.  Then I can decide if I want to
> use it on a per image basis.  Please post your results here too, I'm
> interested in what you find.
> 
> Almost 1:30 here, time for bed. I'm whupped.
> 
> Regards,
> Clayton
> 
> 
> Info on black and white digital printing at    
> http://www.cjcom.net/digiprnarts.htm