img-gif(n) img-gif(n)

NAME
       img-gif - Img, Graphics Interchange Format (gif)

SYNOPSIS
       package require TTkk

       package require iimmgg::::ggiiff  ??11..33??

       iimmaaggee ccrreeaattee pphhoottoo ?name? ?options?


DESCRIPTION
       The  package  iimmgg::::ggiiff  is  a sub-package of IImmgg. It can be loaded as a
       part of the complete Img support, via ppaacckkaaggee rreeqquuiirree IImmgg,  or  on  its
       own, via ppaacckkaaggee rreeqquuiirree iimmgg::::ggiiff.

       Like  all packages of IImmgg it does not provide new commands, but extends
       the existing TTkk command iimmaaggee so  that  it  supports  files  containing
       raster  images  in the Graphics Interchange Format (gif). More specifi-
       cally iimmgg::::ggiiff extends TTkk's pphhoottoo image type.

       The name of the new format handler is ggiiff.  This handler  provides  new
       additional  configuration  options.  See  section  GGIIFF OOPPTTIIOONNSS for more
       detailed explanations.

       All of the above means that in a call like

       iimmaaggee ccrreeaattee pphhoottoo ?name? ?options?

       [1]    Image data in gif format (options -ddaattaa and -ffiillee)  is  detected
              automatically.

       [2]    The  format  name  ggiiff  is recognized by the option -ffoorrmmaatt.  In
              addition the value for the option is treated  as  list  and  may
              contain  any  of  the  special  options  listed  in  section GGIIFF
              OOPPTTIIOONNSS.

GGIIFF OOPPTTIIOONNSS
       The handler provides two options, one for reading from a GIF image, the
       other influencing the writing of such.

       -iinnddeexx n
              This  option  is for reading from GIF files containing more than
              one image (animated GIF's, GIF movies. When  specified  it  will
              read  the  n'th image in the data. The first image is at index 00
              and will be read by default, i.e. when the option is not  speci-
              fied.

       -iinntteerrllaacceedd bool
              If  the  value  of  this option is set to true the image will be
              written using the interlaced sub-format of GIF. The  default  is
              to  write  non-interlaced  files. This option is not implemented
              yet.

IIMMAAGGEE CCOOMMPPRREESSSSIIOONN
       Instead of LZW the run-length encoding  of  Hutchison  Avenue  Software
       Corporation  is  used,  also known as miGIF compression. The miGIF com-
       pression routines do not, strictly speaking, generate files  conforming
       to  the  GIF  spec, since the image data is not LZW-compressed (this is
       the point: in order to avoid transgression of the Unisys patent on  the
       LZW  algorithm.) However, miGIF generates data streams that any reason-
       ably sane LZW decompresser will decompress to what we want.

TTRRAANNSSPPAARREENNCCYY
       If you want to write images to disk which contain transparency informa-
       tion (e.g. GIF89) you need at least TTkk 8.3.

SEE ALSO
       img-bmp,  img-gif,  img-ico,  img-intro, img-jpeg, img-pcx, img-pixmap,
       img-png, img-ppm, img-ps, img-sgi, img-sun, img-tga, img-tiff, img-win-
       dow, img-xbm, img-xpm

KKEEYYWWOORRDDSS
       gif, image handling, tk

COPYRIGHT
       Copyright (c) 1995-2003 Jan Nijtmans 



Img                                   1.3                           img-gif(n)