Path: utzoo!attcan!uunet!husc6!m2c!wpi!dseah
From: dseah@wpi.wpi.edu (David I Seah)
Newsgroups: comp.sys.apple
Subject: GIF files
Message-ID: <1416@wpi.wpi.edu>
Date: 19 Mar 89 17:03:33 GMT
Reply-To: dseah@wpi.wpi.edu (David I Seah)
Organization: Worcester Polytechnic Institute, Worcester, MA. USA
Lines: 32


DOUG@ECL.PSU.EDU writes:
>Can anyone tell me exactly what a GIF file is for? I downloaded one and
>unarchived it, and now it's just sitting on my disk in binary doing
>nothing.. something tells me that it won't be very useful for me.

GIF stands for Graphics Interchange Format (or something close to that).  This
is a file format designed for the universal exchange of computer graphics
images between different machines with different display capabilities.  If I
created a picture on my Apple IIGS, and wanted to share it with a friend who
had an Amiga, I could use a GIF converter (such as SHR Convert) to translate
the Apple IIGS picture format into GIF.  My friend would then use a GIF reader
on his Amiga to view the picture!  

Keep in mind, though, that some images don't "GIF" very well across different
machine types.  A GIF file contains information about the picture's dimensions
and color use.  For example, you download a GIF picture that was originally
created on an IBM PC.  The original picture has 256 different colors out of a
possible 262,144 color map, with a screen size of 320x200 pixels.  All this
information was encoded into the GIF file you just downloaded.  Attempting to
deGIF this file onto the Apple IIe double hires screen (16 colors and
effective 280x192 COLOR resolution) will probably not be worth the effort.  

For the Apple IIGS, there is a program called SHR Convert which will handle
GIF files plus a myriad of other computer file formats.  It is availiable from
35.1.1.43 (or it was).  There is a file there called UT.IIGIF that is a GIF
converter for non-GSs, but I don't remember if it handles double hires or
LAAARRGE bitmaps.  Also, you might want to check out the !INDEX file,
which defines all those file prefixes.  

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