Digital BW, The Print

David,

>There are no direct controls with an RGB driver...

Sad but true.  Although, in the partitioned workflows and with the right
settings, it appears we are able to get sufficient control of the inks to,
for example, lay down an apparently pure light-gray ink in the highlights.

One of the things we've been doing in setting up these machines and writing
the RGB control curves is finding the setting combination that keeps the
dark gray out of the highlights when the Photoshop image adjustment curves
are supposedly turning off those inks entirely. With the wrong settings and
with some of the printers, there will be dark dots in the highlights no
matter what the Photoshop curves are trying to do.  So, the settings can be
critical, and the drivers do not appear to be uniform in what they do.

I think the main reason I'd be interested in using a RIP now is to get
direct control of the black ink.

> ... I was once at an Epson convention booth when the black
>in a particular model of Epson stopped printing entirely.
>What caught the attention of the Epson employee I was
>talking with was not the clog ... but
>the fact that there was a ghost of undercolor in the black text.
>He was as surprised as I was. We both thought that
>full black to any of the Epson
>drivers at any setting always printed K only. ...

I have been curious about that also.  Some other experts claim that the
Epson 100% black is just that.  However, my suspicious are that most of the
drivers do mix in a little color.  Some of the evidence I see is that the
"black ink only" blacks are slightly darker, and I think there are slight
differences in the depth of black depending on which tone curve is used for
the MIS VM system.  This last observation (and I have not spent the time to
see what, if any, pattern there really is) might even indicate that the
driver is taking adjacent colors into affect.

Paul
http://www.PaulRoark.com