Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Carl 
Schofield <scho@m...> wrote:
> I've been struggling with the same problem.  In fact, the 21 step 
> wedges printed with the QuadToneRIP look very similar to 
wedges printed 
> with the Epson driver using the No Color Adjustment setting 
(with a 
> profile), which is known to be non-linear.  I've also tried 
lowering 
> density to get better shadow separation but as you have noted 
this 
> results in a lower black dMax.  However, you can get away with 
a lower 
> density and better shadow separation using the Photo black 
on RC papers 
> without losing as much Dmax.  I don't know of any other ways 
to resolve 
> this problem, but perhaps Roy or others might have some 
suggestions.
> 
> On Monday, March 17, 2003, at 01:45  PM, thericker88 wrote:
> 
> > Hello,
> >
> > This is my first post.
> >
> > I thought I was the only one who liked the look of Black Only 
prints, 
> > then I found this list.  I didn't realize that so many did it and 
that 
> > it was talked about so frequently the abbreviation "BO" was 
coined for 
> > it.  By the way, I don't mind that 2200 matte black is a little 
warm.
> >
> > I downloaded Roy Harrington's QuadtoneRIP because I 
wanted to try the 
> > Black and Light black only print on my 2200.  Now that is 
warm! 
> > Actually, in comparison, my black only prints look totally 
neutral.
> >
> > Now, here's the question that I have.  I've tried a bunch of 
different 
> > densities along with printing out the 21 step grayscale step 
wedge.. 
> > The problem is I can't get deep blacks that still separate. 
When I get 
> > the 100% and 95% to separate, the blacks just don't look that 
dark.  
> > How can I fix this?  The step wedges I've printed with the 
black only 
> > look great despite the slight roughness.  I've set everything 
> > according to the recommended.  The highest density I can 
set while 
> > still getting shadow separation is about 1.1.
> >
> > The more tests I make, the more I feel like I'm running 
around in 
> > circles.  Help please!
> >
> > Thank you!

Unfortunately, I don't have a 2200 to try things out and know
the results.  But this does sound somewhat similar to things
I've seen with quad inks on my 1160.

It seems that the gimp-print calibration is done such that 
there is a linear ink density response up to Density = 1.  But
that doesn't give the maximum possible dMax.  What I've
done with the quad curves is to use a Density = 2 and then
to compensate for a gradual leveling off of the ink density
response I have quite a steep black curve right at the end.

If you look at my CMK separation curve you'll see what I mean.

So for the 2200 what I would try is to use Density = 2 and
change the Black curve.  The idea is to go linearly up the ink
density you got back when you set Density = 1.  Then increase
the slope ending in the top corner.   Without a densitometer
reading I don't know where to tell you to put these points but
these two points in the Black curve should give you the
general idea.  (I=79%,O=61%) and (I=91%, O=76%)  
I've just made these up but if you put then you  can see there's
a break in slope between them -- this is where the dMax
using Density = 1 should be.  Move them up or down to
match dMax at Density = 1, move them right to increase the
shadow detail, left to make sure your whole picture doesn't
get too light.

It's awful hard to say this all clearly so email me if you have
questions about it.

Roy