If you're on a unix machine and don't want to use perl modules, you should check to see if the 'montage' program is installed. (type 'man montage' or 'which montage') It can merge several individual digit images into a single one. Here is a line of code from an early program of mine that used montage in this way...

$image = `/usr/X11R6/bin/montage +display -borderwidth 0x0 +label +fra
+me -geom
etry ${scale}+0+0 -tile ${tiles}x1 $gifs GIF:-`;
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It won't work right out of the box for you, since you'll need the digit images, and then some code to put their filenames into the $gif tag.

Hope this helps.

-Blake