Re: [Gimp-print-devel] How to use special Inks?

[Robert L K. <rl...@al...>]

   Date: Fri, 25 Feb 2000 23:29:23 +0100 (CET)
   From: regis rampnoux <re...@re...>

   On 25-Feb-00 Robert L Krawitz wrote:

   > So this is black & white?  Very interesting.  The driver doesn't know
   > anything about this kind of stuff.  Wanna start coding :-?

   I had a look to photoshop.  If you convert a grayscale image in
   CMYK you have different layers. There is not only the layer black
   which contains information (unlike "The Gimp"). But the print
   plug-ins seems to convert with his rules and seems to use ink
   values like PS. (Sorry, my english is bad, I apologize for that).

Well, the way to get smooth output is to use as many dots as possible
scattered as evenly as possible.  Using CMY to generate black means
that a lot more dots are needed, which makes things appear much
smoother.

   >  MIS Sixtone Inkset - 15%-LC, 25%-C, 45%-LM, 50%-Y, 75%-M,  100%-K

   I interpret (I hope that it is right) the value as:
   for gray between 0-15% use ink from light cyan  
   for 16-25% from cyan
   for 26-45% from light magenta 
   ... 

More or less true.

   This should be interresting to dithering B&W photographies?
   Do you need inks to try?
   who can/want have a look about this?

I have to admit that this would be a really interesting project and
wouldn't be too hard.  The dither_black4 routine isn't quite right for
this, but it would be very easy to adapt it or create a very similar
routine that would do the right thing here (create N planes of output
rather than a log N bit encoding).  Then it's just a matter of hacking
the Epson driver to know about this, and set up the right dithering
parameters (3.1 does this right).

The problem with it is that it's very specialized; there aren't a
whole lot of people (that I'm aware of) using these inks.  I would be
happy to accept a patch for it, if it's well written or easy to fix up
(if you want to try it, I'll write or adapt the dither routine for
you), but we have more pressing issues to deal with, such as
documentation, improving the GUI, improving performance, and so forth.
As a photographer, being able to generate high quality, archival black
& white images in this fashion would be fascinating, though.

-- 
Robert Krawitz <rl...@al...>      http://www.tiac.net/users/rlk/

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lp...@uu...
Project lead for The Gimp Print --  http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton