IM: GIF - Graphics Interchange Format

IM - An Imaging Tool

GIF - Graphics Interchange Format
[File Formats]

Description

Copyright (c) 1987,1988,1989,1990 CompuServe Incorporated.
GIF is a Service Mark property of CompuServe Incorporated.
Graphics Interchange Format Programming Reference, 1990.
LZW Copyright Unisys.
Patial Internal Implementation.
Decoding and encoding code were extracted from GIFLib 1.0.
Copyright (c) 1989 Gershon Elber.

Features

    Data Types: Byte
    Color Spaces: MAP only, (Gray and Binary saved as MAP)
    Compressions: 
      LZW - Lempel-Ziv & Welch      [default]
    Can have more than one image.
    No alpha channel.
    Internally the lines are arranged from top down to bottom.
 
    Attributes:
      ScreenHeight, ScreenWidth IM_USHORT (1) screen size [default to the first image size]
      Interlaced IM_INT (1 | 0) default 0 
      Description (string)
      TransparencyIndex IM_BYTE (1)
      XScreen, YScreen IM_USHORT (1) screen position
      UserInput IM_BYTE (1) [1, 0]
      Disposal (string) [UNDEF, LEAVE, RBACK, RPREV]
      Delay IM_USHORT (1)
      Iterations IM_USHORT (1) (NETSCAPE2.0 Application Extension)

    Comments:
      Attributes after the last image are ignored.
      Reads GIF87 and GIF89, but writes GIF89 always.
      Ignored attributes: Background Color Index, Pixel Aspect Ratio, 
                          Plain Text Extensions, Application Extensions...