Re: [Gimp-print-devel] Epson 740

[Frank v. M. <F.v...@in...>]

On Mon, Apr 24, 2000 at 07:29:52PM -0400, Robert L Krawitz wrote:
>    Date: Mon, 24 Apr 2000 19:54:27 +0200
>    From: Frank van Maarseveen <F.v...@in...>
> 
>    I'm trying gimp 1.0.4 + print-3.1.3 on a RedHat 6.1 box for
>    this printer. This doesn't look good. I have tried various
>    settings in the file->print menu but at best the color dithering
>    was much worse than with ghostscript: I tried versions 5.10 and 6.01, both
>    with .upp files for the Epson 740 which I got from another place.
> 
> What kind of image did you try to print?
I created a test picture containing RGBCMY colored rectangles at
various angles (but not the 0, 90, 180, 270 degree special cases).
Within a rectangle the selected color intensity varies from 0 to 100%.
The low intensity end (i.e. paper is almost white) seems to be a stress
test case for dithering. Most algorithms produce all kinds of small
artifacts due to regularities in the dispersion of dots. This is exactly
what I see when printing camera pictures with light areas (paper on a
desk, tropical beach, light blue sky with a few clouds).

I've given it a few thought and my guess is that these artifacts
(kind of curves, waving patterns or something) might disappear
when the error dispersion is done with a probability inverse
to [the square] of the distance of the center of the pixel using
a random angle. kind of. I'm sure there are statistical functions
(from calculus) which are applicable to my idea. But maybe this
is all silly or is already being done in a way.

Good news:
I tried the print-3.1.3 "Ghost" subdir with ghostscript 6.01
and the very first impression is that "stp" is better that uniprint.

-- 
Frank