Re: [ferret_users] reducing background bleedthrough (white lines/grid) in Ferret PostScript

[Hein Zelle <hein.zelle@xxxxxxxxxxxxx>]

Dear Andrew Wittenberg,

> One question has come up often on the Ferret Users' Group: how does
> one prevent the spurious "stripes," "lines," or "grid" that show up
> in SHADE or FILL plots, which have been output to PostScript?  These
> have been mentioned in several threads:

Instead of modifying the postscript, I do the following (with minor
variations based on purpose): 

1)   convert ps file from Fprint to a properly cropped eps
     cat output.ps | ps2eps -B > output.eps

2)   convert to a high resolution, non-antialiased png
     convert +antialias -density 300 -rotate 270 input.eps output.png

3)   scale (and antialias) to desired size
     convert -alpha off -antialias -scale 35% input.png output.png

ps2eps is a fast and reasonably robust eps converter which trims
almost all ferret output correctly.  convert is from ImageMagick,
available on most linux distributions by default.  You may or may not
need the "-alpha off" option, if the image background becomes
transparent you'll need it.

A faster version (most processing done in memory) which does almost
exactly the same is the following:


1)  gs -dSAFER -dNOPAUSE -r300  -dDEVICEWIDTHPOINTS=864 -dDEVICEHEIGHTPOINTS=864 -sDEVICE=ppmraw -q -sOutputFile=- -f input.ps -c showpage -c quit | pnmcrop | convert pnm:- PNG:output.png

2)  convert -antialias -scale 35% -rotate 270 input.png output.png



Kind regards,

Hein Zelle

-- 

Dr. Hein Zelle
Advisor Meteorology & Oceanography

Tel:    +31 (0)527-242299
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Email:  hein.zelle@xxxxxxxxxxxxx
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