Digital BW, The Print

Ok, so I'm back after a brief hiatus.  This time, I'm armed with a delicious new iMac.  I 
finally made the switch, and I'm not looking back.

So while eagerly anticipating Paul's UT7 inkset, I've dusted off my Ultrachrome carts and 
have been using the stock (Schofield?) curves through QTR to get some nicely neutral 
prints.  The dmax is a little south of where I'd like to to be, so I got to thinking.

I printed and scanned back in the greyscale ramp that came with QTR, and sure enough, 
the histogram is pretty compressed from about 80-100%, and the black point never quite 
gets down to 0.  I'm not sure how to get more black out of the UC inkset, and I was 
wondering if there was a way (preferably automated) that I could take the difference 
between the original curve image and the scan, and turn it into a photoshop curve.  I'm 
new to building curves, and I see how they can be labor intensive.  I have no problem 
doing it the hard way, but can't help but wonder if there is a smarter way to do it.

The next step would be creating a curve for QTR from this photoshop curve.  I assume I 
would be adding the 2 curves together, but I'm not really sure how to do that.  I don't 
really grok how to make the leap from a monochrome curve to seperated CMYK values.  
Are they just mixed evenly?  I guess this is more properly done with a densitometer, but I 
don't have one availabe, and I figured that an accurate scan would suffice.

How far off am I on understanding this?

Hi Justin,

The main things that will effect dmax are: kind of paper, kind of black ink
and quantity of ink.  If you are using the ink & paper that the curves were
made for you are likely close to the limit.

Scanning the grayscale ramp really doesn't tell you much about dmax.  The
fact that you don't get all the way to 0 (or 100%K) is purely a function of
where you or the scanner software set the black point. 

My personal favorite would be to use Hahnemuhle Photo Rag with matte
black ink (either Epson UltraChrome or MIS Eboni).  Increasing the quantity
of ink would be the ink limits in the profile (BOOST_K would be the one
to try) but without a densitometer you might not get as smooth a final
curve.

Roy


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "justinflorentine" 
<justin@b...> wrote:
> Ok, so I'm back after a brief hiatus.  This time, I'm armed with a delicious new iMac.  
I 
> finally made the switch, and I'm not looking back.
> 
> So while eagerly anticipating Paul's UT7 inkset, I've dusted off my Ultrachrome carts 
and 
> have been using the stock (Schofield?) curves through QTR to get some nicely 
neutral 
> prints.  The dmax is a little south of where I'd like to to be, so I got to thinking.
> 
> I printed and scanned back in the greyscale ramp that came with QTR, and sure 
enough, 
> the histogram is pretty compressed from about 80-100%, and the black point never 
quite 
> gets down to 0.  I'm not sure how to get more black out of the UC inkset, and I was 
> wondering if there was a way (preferably automated) that I could take the difference 
> between the original curve image and the scan, and turn it into a photoshop curve.  
I'm 
> new to building curves, and I see how they can be labor intensive.  I have no 
problem 
> doing it the hard way, but can't help but wonder if there is a smarter way to do it.
> 
> The next step would be creating a curve for QTR from this photoshop curve.  I 
assume I 
> would be adding the 2 curves together, but I'm not really sure how to do that.  I 
don't 
> really grok how to make the leap from a monochrome curve to seperated CMYK 
values.  
> Are they just mixed evenly?  I guess this is more properly done with a 
densitometer, but I 

> don't have one availabe, and I figured that an accurate scan would suffice.
> 
> How far off am I on understanding this?