Digital BW, The Print

Hello Paul,

>If I print a test target in NCA mode on my 2200, the 0,0,0 patch
>generally looks a tad lighter than the nearby black patches. It 
>appears that 0,0,0 translates into pure K, while other small 
>values produce CMYK combinations that are actually darker. I would 
>think that good profiling software would be smart enough to avoid
>pushing the printer into its pure K output range,
>but apparently it isn't.

I'm not sure what you mean by "CMYK combinations" when I'm printing BO
from only the black cart.  Doesn't that mean combinations of various
inks?

I have been working with the assumption that in a grayscale mode image
a pixel of 0 RGB value is as black as is possible, and that a patch of
0 pixels will be printed with the blackest ink combination that the
printer is capable of (which in a BO print would be 100% coverage of
dots).  

The big assumption is that more ink was laid down in the 2nd print. 
Based on that: 

I was talking with Steve K. about it today and we wondered what there
was about the paper that would make the patch look darker the 2nd
time, when the first print had what looked like 100% coverage.  It
would mean the paper is capable of looking darker with that extra ink
(up to a point I suppose).  That would mean that the quantity of ink
is a factor as well as 100% coverage of dots.  Some questions:

1) Why did the S-curve, which didn't move the zero anchor point and
theoretically didn't change any already zero pixels, make the printer
put down more ink in a patch that was already solid zero pixels?

2) What does "more ink" actually mean in this case? Two squirts on
each dot location instead of one?  Dot locations that overlap?

3) Why does adding more ink to an already 100% covered area of pure
black increase Dmax?  Does a lesser amount of ink sink in deep and
leave less on the surface, and a greater amount "fills it up" so to
speak?

4) Will all papers react to extra ink that way?

5) Here's the biggie: The paper is capable of much better Dmax if you
give it more ink.  I found that I can give it more ink with the curve
(for whatever mysterious reason), but it ruined the pic because the
rest of the image was too contrasty.  How can I make the printer give
it more ink in zero RGB zones without changing the contrast?

One reason I'm so interested is because the paper in question has
paper color and ink color that are nearly identical to Photo Rag, but
considerably less Dmax.  But the 2nd print was so much closer to PR
that it could easily become a PR substitute at a far lower cost and,
from my testing so far, without the flaking problem.  But how to get
more ink to the paper in the black areas...

Thanks for the input.

Regards,
Clayton


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