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From: seb3@gte.com (Steve Belczyk)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: GIF to SPC convertors
Message-ID: <10984@bunny.GTE.COM>
Date: 12 Apr 91 13:20:40 GMT
References: <1991Apr9.105007.10362@newcastle.ac.uk> <1991Apr9.134525.24039@informatik.uni-erlangen.de> <1991Apr12.011732.8868@convex.com>
Organization: GTE Laboratories, Waltham MA
Lines: 28

In article <1991Apr12.011732.8868@convex.com> rosenkra@convex.com (William Rosencranz) writes:
>now that i think of it, i think the PBM package includes giftopbm and pbmtospc
>converters. i have not tried these, however. with a shell that can pipe,
>you should be able to do:
>
>	giftopbm file.gif | pbmtospc >file.spc

That would be:

  giftoppm file.gif | ppmtospu >file.spu

If the GIF was not 320x200, you'd have to do:

  giftoppm file.gif | ppmscale -width 320 -height 200 | ppmtospu >file.spu

Ppmtospu uses the same algorithm to convert to Spectrum that GIFSPC
uses.  However, since ppmscale uses a much better algorithm to scale a
picture that is not 320x200, large GIFs would probably look much better
using PBMplus instead of GIFSPC.  Ppmtospu also has a 4x4 dithering
option which GIFSPC does not have.

BTW, if anyone wants to build a better GIF to Spectrum convertor, the
sources to giftoppm and ppmtospu would be a great place to start.  I
still have most of the source to GIFSPC, but it is very poorly written,
and slower, compared to giftoppm, ppmscale, and ppmtospu.

Steve Belczyk   CIS: 75126,515    BBS: +1 508 664-0149 (2400 bps)
seb3@gte.com    GEnie: sbelczyk   UUCP: {harvard,vaxine}!bunny!seb3