Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Mike Botelho" 
<mfractl@h...> wrote:
> 
> I'd like to thank everyone for all the advice.  At first, I started 
> to reply to each and every response, but I've started to realize that 
> I will simply be repeating myself over and over if I reply to 
> everyone that's offered their vote on this subject.  Yet, the 
> response here is so much more helpful than I've experienced 
> elsewhere, I definitely wanted to acknowledge it.  So thanks again to 
> all.
> 
> Also, one of the posts I just read reminded me of a question I'd 
> thought of last evening...
> 
> Since the use of colored inks seems to be a source of problems when 
> printing B&W with the Ultrachromes, why not just use the Light Black 
> to provide the lighter tonalities instead?  I know that 'black only' 
> printing results in noticable dots that some find objectionable and 
> that the use of colored inks eliminates this, but wouldn't the use of 
> the Light Black ink eliminate this also?  In fact, isn't that why the 
> Ultrachrome printers have a Light Black cartridge?  So, I'm 
> wondering, am I missing something here?  Does the inclusion of 
> colored ink somehow produce smoother gradations than simply using the 
> lighter tones produced by the Light Black ink?
> 
> Mike

These are all good observations and questions.  The answers are very
intertwined and interdependent.

First and foremost is the Epson driver doesn't give you that option.
It allows Black-Only which is just the one dark black ink giving you
noticable dots, and it allows the full Color inks in which it decides the
mix of light-black and color inks -- the user and the profiles haven't
much control of ink usage.

Second is that the light-black ink is not neutral gray.  It's quite warm,
basically a brown rather than neutral.  The point is that a two ink print
will be very warm not neutral.  This can look nice but most people want
at least the option of neutral B&W.

So the point of all the mentioned RIPs -- ImagePrint, IJC/OPM and QuadToneRIP
is to start with the two-ink (black and light-black) grayscale print and
add a small but just enough light-cyan and light-magenta inks to 
neutralize the warm tone of the light-black.  The advantage is that it
uses a minimal amount of color inks and has minimal metamerism.  It's
also possible to vary the amount of light-cyan and light-magenta to
allow slight toning of the print -- warm to cool or selenium.

Finally, I think there's one more slight twist in the 2200 vs dedicated B&W.
Despite the name "light-black" it's really a pretty dark ink -- about the
same as the darkest gray of the quadtone inksets.  The printers have
such small drops of ink that for the most part, most people don't see or
don't care about these dots -- but the dedicated B&W inks have a lighter
gray that at least theoretically gives even smoother highlight grays.

Roy
www.harrington.com