Re: [Gimp-print-devel] Stylus photo 870

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

   Date: Fri, 5 May 2000 23:51:30 +0000
   From: Jean-Marc Verbavatz <ver...@if...>

   > Huh.  That's very interesting, and doesn't accord with my experience.
   > I would expect stock 3.1.3 to be the least grainy, followed by the
   > current repository and then 3.1.2.  3.1.2 might be denser, which would
   > reduce the perceived grain.

   Right, this is not what I meant. Saying that the current repository
   was lousy was an overstatement. I meant it's too dark to tell. For
   3.1.2 I meant a version that I had modified. I would otherwise
   agree with you.

The current repository prints too dark?  I thought I reduced the
density.

   I think the density ratio between colors is simply not one. I'll
   send you a patch over the week end, that mostly fixes grays. To get
   it absolutely right, we need to address the grain issue first
   though. To fix red and blue, the only thing I came up with were hue
   adjustements.

I think you're probably correct.  See my next message, though, about
grain.

   > I think that the black threshold is a bit too low right now.

   Yes indeed. The new k_lower in print-escp2 .138, looks better already. That
   does not totally fix the problem, but helps very much.

We can always tweak it a bit more.

   Well this does not improve things in my opinion. It is lighter as
   you would expect, but grain remains. The change in k_lower is much
   more useful.

OK, we won't go down that path.

   Have you tried to print a black and white picture in color mode ?
   I've noticed that, beyond the greenish tone, it shows diffuse
   magenta grains, particularly around transitions and I could not
   figure out why. Interestingly, I've noticed that (now that black is
   better), grain in color pictures was mostly magenta as well and in
   fact localized in exactly the same regions. Is it just me ?

You know, I've seen some oddities with (not so diffuse) magenta in
some things at extremely low densities.  At this point, I don't know
if it's due to the image or if magenta alone is somehow being handled
incorrectly.

-- 
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