Digital BW, The Print

Hello Peter,

>When I print a 100 stepwedge using different ABW settings I find it 
>difficult to see a totally neutral print. Maybe its my eyes but 
>I see some colour. Would appreciate what you see. Perhaps I'm being 
>to fussy!!

No you aren't being to fussy, it's one of the challenges of making BW
with color inks.   As good as the ABW system is, it isn't perfect.  At
any given setting, the color balance may shift slightly along the
ramp.   I've found that these instances of what I call coloration are
most often apparent in the middle gray zones.  A high contrast print
with few grays areas can look neutral, while another print with same
setting on same paper but with large middle gray areas can look
pinkish/greenish, etc (this has been discussed here before - Tyler or
someone else might pop in here with a better explanation...).  

There also seems to be some sort of interaction between the colors. 
For example, when increasing the H value (towards magenta), at certain
points the print may look a bit less pink than on a lower setting.  My
theory is that certain colors "harmonize" at certain ratios, and there
is a balancing or canceling effect (I'm not saying this is what's
actually happening, it's just my attempt to describe an effect I see).

Suppose, for example, I want to increase warmpth and my goal is a
brown that looks brown, without any pink or green tinge.  I find that
at any given increased H setting, the amount of non-brown coloration
varies according to the V setting.   An H value of 6 for example, can
look less pinkish than at 5, depending on the V setting.

To complicate matters, these effects differ on various papers.  So
what works beautifully on VFA may not work as well on Dourian or
Merlin Natural.  And I'm assuming that K3 and K4 will be different (I
haven't used K4).  

So the bottom line is we have to experiment systematically and take
notes.  My experience is that every paper can have one or more sweet
spots where everything harmonizes and produces what I call a
convincing photographic tone that looks even across the ramp. 
sometimes they are easy to find, others more challenging.

BTW, this problem is not the exclusive domain of color inks.  I found
essentially the same problem, in a slightly different form, with UT7
on my 2200.  I was never fully satisfied with any of it's tones. 
There was always a bit of tinge or dullness of some sort that
I never could eliminate, and spent countless hours tinkering with QTR,
curves and ink mixtures (not to mention $ on ink/paper), only to crawl
back in failure to BO printing after each round to rest up and lick my
wounds before trying something else.  

I saw the same thing in print exchanges with prints from all the
different systems in use at the time (various inks, RIPS, papers,
printers and techniques).  Seeing a really convincing tone was a rare
occurance.  Nearly four years of constant frustration, which ended
with the 2400.  It took me a few months to figure it out (actually
still learning new things), but I finally arrived at a place where I'm
getting convincing tones and most of my energy is focused on the
photography and not on printing struggles.  

Aside from the tone issue, the 2400 has a really nice combination of
smooth gradation and luminance, avoiding the dull look of many full
ink systems.  ABW isn't perfect, but for me it's several orders of
magnitude better than what we had before.  I finally am back to being
a photographer and not a mad scientist tinkering endlessly in a
laboratory <g>.


Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm