The Graphics Interchange Format(c) specification is the copyrighted property of CompuServe Incorporated. GIF(sm) is a service mark property of CompuServe Incorporated. As this package existed before UniSys's lawyeritis attack of New Years' Day 1995, it is grandfathered in under their license terms and you do not have to pay fees for using it.

This package has been released under an X Consortium-life freeware license. Use and copy as you see fit. If you make useful changes, add new tools, or find and fix bugs, please send your mods to the maintainers for general distribution.

The library includes program-callable entry points for reading and writing GIF files, an 8x8 utility font for embedding text in GIFs, and an error handler. GIF manipulation can be done at a relatively low level by sequential I/O (which automatically does/undoes image compression) or at a higher level by slurping an entire GIF into allocated core.

This library speaks both GIF87a and GIF89. The differences between GIF87 and GIF89 are minor: in the latter, the interpretation of some extension block types is defined. The library never needs to actually interpret these, but giftext notices them.

Utilities

Conversion Utilities

gif2bgi

display GIFs on IBM PC displays using the BGI (Borland) driver

gif2epsn

dump images saved as GIF files on Epson type printers

gif2herc

display GIFs on IBM PC displays using the Hercules graphic card

gif2iris

display GIFs under SGI NeWs window system

gif2ps

print GIF file on laser printers supporting PostScript

gif2rgb

convert images saved as GIF to 24-bit RGB image(s)

gif2rle

convert images saved as GIF to RLE (Utah raster toolkit) format

gif2x11

display images saved as GIF files under X window system

raw2gif

convert raw 8-bit image data into GIF files

rgb2gif

convert 24 bit images to a GIF image using color quantization

rle2gif

convert images saved as RLE (Utah raster toolkit) to GIF format

Test Pattern Generators

gifbg

generate a single-color test pattern GIF

gifcolor

generate color test patterns

gifwedge

create a test GIF image resembling a color monitor test pattern

Image Manipulation Components

gifasm

assemble multiple GIFs into one, or burst a multiple-mage GIF

gifclip

clip or crop a GIF image

gifclrmp

modify GIF image colormaps

gifcomb

combine 2 GIF images of exactly the same size into one

giffix

clumsily attempts to fix truncated GIF images

gifflip

flip GIF image along X or Y axis or rotate by 90 degrees

gifinter

convert between interlaced and non interlaced images

gifovly

generate one composite GIF from a multiple-image GIF

gifpos

change a GIF's screen size or recondition it.

gifrotat

rotate a GIF through any desired angle

gifrsize

resize a GIF by deletion or duplication of bits

gifburst

burst a GIF image into subrectangles.

Report Generators

giftext

print (text only) general information about a GIF

gifhisto

generate color-frequency histogram from a GIF

GIF Composition Tools

icon2gif

converter/deconverter to/from an editable text format

text2gif

generate GIF images out of regular text in 8x8 font

gifinto

end-of-pipe fitting for GIF-processing pipelines

gifcompose

use giflib tools to compose images

C Code Templates

giffiltr

template code for filtering a GIF sequentially

gifspnge

template code for filtering a GIF with in-core operations

Some of the utilities require memory on the order of the whole screen, while others read one scan line at a time. Each utility HTML file has entry called Memory Usage which will be one of:

Line

memory required is on the order of one scan line

Image

proportional to the size of the biggest image in GIF file

Screen

proportional to GIF screen size

Library Functions

Unless you are on a 286 or some other very memory-limited machine running under DOS, you probably want to use the second group.

Detailed documentation on the library entry points is in gif_lib.html. Library error codes are described in liberror.html

The GIF Standard

History