Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!hellgate.utah.edu!uplherc!wicat!sarek!gsarff
From: gsarff@sarek.UUCP (Gary Sarff)
Newsgroups: comp.sys.amiga
Subject: Re: GIF to IFF
Message-ID: <00342@sarek.UUCP>
Date: 10 Dec 89 04:01:30 GMT
References: <637@tau.sm.luth.se> <5422@wpi.wpi.edu> <4186@nigel.udel.EDU>
Organization: Programmers in Exile
Lines: 27

In article <4186@nigel.udel.EDU>, new@udel.edu (Darren New) writes:
>In article <5422@wpi.wpi.edu> jdutka@wpi.wpi.edu (John Dutka) writes:
>>There is a program, called gif2iff, that will do this for you.  It comes
>>with two programs, giftotmp, and tmptoiff.  It works ok, but it chokes on
>>GIFS that are bigger than the Amiga screen.
>
>However, I looked at this one.  It seems the TMPtoIFF is what chokes.
>The GIFtoTMP seems to work fine.  The temp-file format is just a
>color map and a fully decompressed (1 byte per pixel) non-interleaved
>easy-to-understand big file.  I think it would probably be easier
>to make this one work than to rewrite from scratch.  I used it
>because the GIFs I was viewing were 16-level grayscale, so the
>temp file didn't need any color conversions.  Please let me know if
>anybody fixes this to work on larger forms. -- Darren

GIFtoTMP does have a problem with GIF files that are stored interlaced.  This
is not the same thing as amiga interlaced video or anything like that.  The
GIF file will store (I may have the details wrong), every 8th line of the
picture, then every 4th, every 2nd then all the odd ones, (may be other
schemes too) but what GIFtoTMP will do is decode the GIF into a TMP file,
(basically a bitmap with color info at the front) as if all the scan lines in
the file were sequential.  If you look at this on an amiga screen what you
will see then is 2,4, or more small horizontal versions of the same image,
each smaller vertically than the one before, direct result of decoding
sequentially when the file is storing the scanlines in interlaced GIF form.
I sure wish someone would fix this!  Anyone know how to contact the author of
this program?