Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Ernst Dinkla <E.Dinkla@...> 
wrote:
>
> Paul Roark wrote:
> > Hi Jim,
> 
> >> The downside ... is the increased grain in the mid-tones...
> >> With my eye 1 foot from the 8x10 print I can clearly 
> >> see the extra grain. ...
> > 
> >> (Note: my wife, who does not have much experience in 
> >> comparing B/W prints, could not detect the difference 
> >> in grain)
> > 
> > That's the same reaction I'm getting.  We can see the difference, but most
> > viewers can't.  I even took samples to a group of fine art B&W printers at a
> > B&W gallery.  None of them saw the problems I was worried about.
> > 
> > So, I stopped worrying about it.  The fine grained structure is there in the
> > midtones, but, fortunately, it is not like the large, visible dots in the
> > highlights that I did find irritating with the older printers.  It looks to
> > me like a print from a fine-grained film, and as many silver printers found,
> > a sharp fine grain actually gives the illusion of more sharpness to a print.
> > 
> >> I am now wondering if I try increasing the number of Eboni inks 
> >> to 4 or more will this help to reduce the grain while keeping 
> >> the current dmax?
> > 
> > I played briefly with up to 6 inks and thought the optimum might be 4.  The
> > 3-ink version was actually smoother than the 6 ink version.  I did not see a
> > significant difference in the grain structure with any of the versions
> > between 3 and 6.
> 
> > Back to the issue of smoothness, note how much smaller the highlight dots
> > are than the midtone graininess.  (See the magnified scans at page 2 of
> > http://www.paulroark.com/BW-Info/R1800.pdf )  I think, like with silver
> > grain, we're not seeing the individual dots, but a pattern -- perhaps close
> > to random -- of how the ink is distributed.  It makes me wonder if there is
> > a way to optimize the curves to avoid some of it.  So far, I have not found
> > such.  As with silver grain, there may be a random pattern that is
> > unavoidable.
> 
> Paul,
> 
> 
> I still have some worries about the dotgain control with 
> Multihead BO and the small dots. Your observation of the 
> pattern fits that. With BO the midtone is 50% black dot on 
> 50% paper white, exactly where dotgain with conventional 
> fine screens in offset have a problem. In that case at bit 
> of dotgain influences the checker board formation at say 45 
> % where it should happen at 50%. By using ellipse shaped 
> dots the pattern formation can be regulated over a range 
> where say at 40 % linear chains are formed at 45 degr. and 
> at 60 % the the rest follows. That made it smoother and 
> better to control. Later on stochastic screens followed but 
> in a sense there still is that point where the dot pattern 
> flips from black dots on white paper to white paper holes in 
> a black layer. Paper coating consistency, humidity, speed of 
> printing (smaller prints on a big machine) all influence 
> that point and with black ink it is then yes or no.. There 
> must be some literature on how to regulate that pattern 
> formation but the consistency issue remains.
> 
> Met vriendelijke groeten,  Ernst
>

Ernst,

I'm not sure I understand your comments.  With inkjets there's no notion 
of dot shape -- they are just drops out of the piezo jet.  I agree that smaller
dots have slightly more dotgain but the linearization and/or gray ICC profile
measure the actual densities and compensate for any dotgain differences.

I have some of Paul prints and my feeling with them is more of an overall
sandpaper feeling if you get up close to it.   One effect that may be happening
in the midtones is that there are two pseudo random dithering patterns from
two inks overlaid.  The interaction is more truly random giving the possibility
of dot doubling/clumping on a minute scale.  (it's a little like moire patterns but 
there's no overall regularity).   It may be this randomness however that helps 
get rid of banding side effects.

Roy