Digital BW, The Print

----- Original Message -----
From: "gaberegalbuto" <gaberegalbuto@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Wednesday, October 16, 2002 10:55 PM
Subject: [Digital BW] CMYK curves


> Here's one for you piezo gurus out there...
>
> I've just started with quads, working on my epson 740 with MIS FS and the
curves so graciously contributed by David Shechter.  Great results, but
still room for improvement.  Being the technical, got to do it myself kinda
guy I'm looking to creating my own curves and really nailing the 5% steps on
various papers with maximum quality and minimum ink.
>
> My first question is this, why work in RGB?  I understand that the epson
driver is native RGB, but it seems that working CMYK curves and then
converting back to RGB would allow much greater control over the inks.

Gabriel,

Well I agree with you in principle but in practice you would just be adding
another step of data manipulation. What people are doing with the RGB
separation curves is to limit the individual inks to certain tonal ranges.
The curves are designed to trick the Epson driver and it is amazing that the
workflows work so well.
>
> I created an image <http://www.regalbuto.net/cmyrgb.jpg> with areas of
pure CMYK and RGB and printed it straight.  In the print, R had a density of
~50%, and G & B were nearly identical at ~84% & ~85%.
>
> R,G,&B each require nearly 100% of two inks to create!  When we're working
with RGB curves aren't we then moving two values at the same time when it
might be easier to move one?

Ideally you want to be working with CYMK or better CcYMmK driver that gives
you individual control of each ink. The closest to that you can get for a
reasonable price would be to get Adobe PressReady and one of the supported
printers. It will support a 1280 event though it is not listed. PressReady
thinks it is a 1270.

For more info on separation curve techniques check the Files section of the
group and check out Dan Culbertson's FTP site. It is in the links under
Photographers.
>
> I'm going to give it a try, starting from scratch.  I hope that anyone who
can convince me otherwise will pull out some forgotten odorless stop bath
and save me from the madness.

At least read what is available and ask some questions. A lot of people have
been down this road before and you may save yourself a lot of time.

Martin Wesley