[Gimp-print-devel] First experiences with an 870

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

Well, I hooked up the 870 today.  Here's the first things I noticed:

1) The standard Epson density (.6'ish) is all wrong for this printer.
   I had to scale it to 1.3 (which really means 1.3 * .6, or about .8)
   to get anything that looked even remotely reasonable.  Even that's
   a bit too low (I'm using photo glossy paper).  I also had to knock
   down both gamma and brightness a bit (.9 gamma and 80 brightness;
   that gamma might be just a bit too low).  Ron van Ostayen suggested
   a value of 1.6 for his ESC 900; that creates solid blacks, but it
   definitely drops too much ink (see below).

   This might explain why people with 900's are complaining that
   output is too light.  Maybe all the variable dot size printers need
   adjustment.

2) The ink dries very slowly.

3) Pale tones are very good indeed.  Gray is very neutral.  However,
   under a loupe there's some weirdness going on.  I think that the
   error spread setting (controlling how widely the error is diffused)
   is too high.  That's not surprising; the spread settings are set up
   for single dot size.

4) Mid and dark tones are grainy.  It's less obvious when I push the
   density up.  It might be a sign that the dither algorithm has
   problems here; it might also simply be a sign that the density is
   too low.  The grain looks a little bit like "shadowing" from large
   dots, but not entirely.

5) Using the smallest dot size from the dark inks makes the grain
   worse.  That doesn't particularly surprise me; it's not laying down
   a lot of ink, but it's printing quite dark.  We may be better off
   not using this.  Or maybe we need to find a way to use it only in
   heavy gray situations.

6) The printer is nearly silent -- a nice change after the noisy EX.

7) I think the high density results in too much ink being dropped
   (which is bad because of the slow drying ink and its expense).
   Jean-Marc Verbavatz had an idea about an ink budget.  I think
   that's a great idea and needs some more study.  We also need to
   look at other ink reduction techniques.

8) Printing multiple images on the same page by means of multiple
   print runs is troublesome.  Think slow-drying ink.  Also, even
   after having dried for over 5 hours, the rollers still managed to
   pick some ink off the paper.  This is less than thrilling from a
   development standpoint; I like to print very small images 25 to a
   page.

So we have some work to do on this...

-- 
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