Re: [Gnuplot-info] pm3d problem

[Ethan M. <merritt@u.washington.edu>]

On Thursday 27 September 2007 12:17, Hans-Bernhard Br=F6ker wrote:
> Henry S. Alken wrote:
>=20
> set term postscript enhanced
> set out "test.ps"
> set pm3d map
> set samples 100
> set isosamples 100
> set palette gray
> set palette gamma 0.5
> splot sin(sqrt(x**2 + y**2))/sqrt(x**2 + y**2)
>
> > -- and I look at the file test.ps, the plot looks worse than the x11
> > version -- there are white grid lines throughout the image making it lo=
ok
> > pretty bad. Does anyone know how to get rid of these ugly grid lines?
>=20
> Turn off antialiasing in ghostscript, and they'll be gone.
>=20
> [CC to -beta]
>=20
> Gents, hadn't we fixed this a *long* time ago?

=46or what it's worth, the postscript plot output from 4.2.2 using those
commands produces no white grid line artifacts when viewed here
via ghostscript version 8.15.3 and gv version 3.6.1.
Toggling the anti-aliasing does not visibly change the rendered image.

The current ghostscript viewing glitches that I know about are:

1) Pattern fill areas are invisible unless you turn off antialiasing.

2) solid-fill areas made up of many adjacent rectangles, e.g. the
   colorbar in a pm3d plot, sometimes suffer from spurious grid lines.
   I do not know the cause of the "sometimes", but suspect it is due
   to different ghostscript versions.  These lines are rendering
   artifacts, not coordinate errors in the file.  They shift in position
   as you change the viewer magnification setting.

Both are known ghostscript bugs, and I don't know of any easy way to
fix things on our end.  We have speculated that using a scaled matrix
operation (as used in the "with image" code) to draw the colorbar all
in one go might work around the problem, but nobody has coded it up to
confirm this.

=2D-=20
Ethan A Merritt