Subject: Re: CCL:Presentation graphics

From: Bob Funchess <[email-masked]>
Date: Thu, 2 Oct 1997 20:18:03 GMT

[email-masked] wrote:
> 
> I'm looking for a converter program which will take a screen capture
> image (e.g. an RGB file from the SGI snapshot utility, or a
> postscript file generated from it) and generate a high quality
> postscript file.  By high quality, I mean with the jaggies removed
> from letters and edges of smooth curves, and some color/pattern
> dithering for shaded surfaces, etc.

Most printers will automatically handle dithering for any color they
can't reproduce as a pure tone, so you're probably better off leaving
that and concentrating on smoothing the edges unless you _really_
dislike the way the printer's doing it.

In general, there's no magic way to recover lost detail, though some of
the painting/photo-refinishing programs these days are capable of
amazing things and would be worth looking into.  Normally the feature
you need will be called something like "smooth" or "blur", or possibly
"convolve" or "filter".

If you don't have access to a program like that, you could try rescaling
the image to the size (in terms of number of pixels) that you need, and
then using a convolution function to blur the jagged edges a bit; SGI
has tools for doing this sort of thing in the imgtools subsystem on the
IRIX CD-ROMs.  There are also some programs available from their website
(go to http://www.sgi.com/ and poke around a bit).

As for the text, personally I'd suggest removing it from the original
bitmapped image whenever possible and adding real postscript text later
using showcase or something similar.  It may be tricky to do that if the
text overlaps something other than the background, though.

    Regards,
           Bob Funchess

-- 
Dr. Robert B. Funchess                    [email-masked]
Senior Scientist, Scientific Support      Voice (619) 458-9990 x738
Molecular Simulations Inc.                FAX   (619) 458-0431
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San Diego, CA 92121-3752                  http://www.msi.com/