Transparency... in MS-DOS

How to use transgif with MS-DOS

Jeffrey Friedl wrote a perl script named "transgif" that twiddles the bytes of a GIF to give it a transparent color. Transgif was originally written to run under UNIX, but, according to some experimentation by Michael Spencer, with a few simple changes, it will work under MS-DOS.

Getting transgif

You can:
- get transgif from Jeffrey's site, or
- get it from my web server.
The version of Transgif I point to here has been modified to work with MS-DOS. The version at Jeffrey's site will always be the latest version (mine may be off by a week or two), but Jeffrey's web server seems to be on the other end of a very slow connection, and is down a fair amount of the time. At the moment (12/6/94), my copy of transgif is the latest version Jeffrey has.
When you fetch transgif, you should save it as is in a file. I'll call the file "transgif", to make things easier. If you use a different filename, you should replace the name "transgif" with that name when you invoke commands. :-)
If you don't already have Perl for MS-DOS, you should ftp a copy of it, also. You can get Perl executables for machines with at least a '386 processor from oak.oakland.edu.
There may be binaries for older CPUs ('286, 8086) in the directory /pub/simtelnet/msdos/perl/
If you didn't fetch the version of transgif that I fixed to work under MS-DOS, you'll need to edit the transgif script:
You'll need to add two lines to transgif. You can do this using any plain-ASCII editor, like EDIT.COM (or EDLIN.EXE) that come with DOS, or any word processor that allows you to edit files in plain ASCII format.
Add these two lines after the line that says "open( INPUT..." :
```
  binmode( INPUT );
  binmode( STDOUT );
```
That's all you have to do to install transgif! :-)

Using transgif

Under MS-DOS, to run the program, you can run a command like this one to run the script. (You should read the beginning of the script for instructions on how to tell transgif which colors to transparentize.) :

perl transgif -1 small.gif > fixed.gif

Jeffrey (the author of the program) wrote documentation for transgif. (In case his web server is unavailable, I made a copy of his documentation.) Alternatively, you can just 'more' the program; it explains itself somewhat. :-)

Please feel free to let me know what you think.

-Eric Mumpower (nocturne@mit.edu)