GENWiki

"What Is GIF?" Compuserve; May 28, 1987 Info on the .GIF file format. Posted by: Jim The Eagle

Introduction

        CompuServe has developed a new  Graphics  Interchange  Format
   (GIF)  designed  to  serve  a  wide variety of graphics needs both
   within the CompuServe  product  environment  and  as  a  universal
   standard  by  which  graphics can be exchanged between any parties
   through a network.  This document serves as a  simple  explanation
   of what GIF is and what it is capable of.

What is GIF?

        GIF (pronounced "Jif") is a mechanism of storing high-quality
   color graphics images in a way that can be exchanged between users
   of differing hardware.  For example it allows images created on an
   Atari  ST  to be displayed on a Commodore Amiga or IBM-PC and visa
   versa.  The GIF format allows for very high resolution, full color
   images  that  can  be  used  in  any application that requires the
   display of graphics information.

What Kind of Images can GIF be Used For?

        GIF images can be part of, but not limited to  the  following
   applications:

1. Full color associate photo board
2. Business charts and graphics
3. Merchandise catalogs
4. Technical documentation
5. Schematic diagrams for field service personnel
6. Color radar maps
7. Medical illustrations
8. Art gallery
9. Exchange of user-created images

How Much Resolution Can an Image Have?

        In terms of pixels, or image dots, GIF is capable of defining
   images  of  over  16,000 by 16,000 individual dots.  This compares
   with the average microcomputer screen of 320 by 200 pixels.   Even
   laser printers are generally limited to about 2000 by 3000 pixels.
   GIF technology is adequate for graphics applications for years  to
   come.

How Many Colors Can a GIF Image Have?

        Any  GIF  image  can  have  up  to  256  simultaneous  colors
   contained  within it.  Each individual color can be defined out of
   a possible set of 16 million colors,  making  photographic-quality
   images possible.

Does This Mean an IBM-PC Cannot Display GIF Images with 256 Colors?

        All  GIF  images can be processed by all  GIF  software.  The
   software  is  designed  to  make   the  best  use  of  a  specific
   hardware's capabilities  with regard to colors.  A best  match  is
   made between a desired color in the image, and the possible colors
   the hardware can  display.   Generally, detail of an image will be
   lost, but it should still be  recognizable.  On  the  other  side,
   any image originating  from  an IBM machine should display exactly
   on a more capable microcomputer.

How Large are the Image Files in GIF?

        This will vary a great deal depending on the number of colors
   present,  the  size of the image and the amount of detail present.
   GIF uses a sophisticated compression method that reduces the  file
   size to between 1/2 to 1/8 of the original file size of the image.
   This  means  that  even  complex  images   can   be   economically
   downloaded.   An  example  is an Atari ST image file of 320 by 200
   pixels and 16 colors which would require 32,000 bytes on the Atari
   might only require 8,000 bytes in GIF format, a space savings of 4
   to 1.

What Micros can Support GIF?

        Currently CompuServe has developed software for a  number  of
   microcomputers  to display or create GIF format files.  Additional
   hardware will be supported as time  goes  on.   The  GIF  standard
   document  will  be  made  public  and  third party authors will be
   encouraged to create additional GIF software for  other  hardware.
   Machines supported currently include:

1. IBM-PC/MS-DOS family with CGA or EGA graphics boards
2. Commodore Amiga
3. Atari ST
4. Macintosh family

        The software files can be found in the  appropriate  hardware
   FORUMS and in the Picture Support Fourm (GO PICS).

Where are the GIF Files that can be Displayed?

        Currently many GIF files are available in DL2 of the  Picture
   Support   Forum.    Each  appropriate  hardware  forum  will  also
   accumulate GIF files  as  time  goes  on.   The  CompuServe  FORUM
   software  has a GIF file type established for uploads of GIF image
   files.