GD 1.18 has been outdated since uhm forever :) GIF support hasn't been in there since 1.6. GD does JPeGs as well as PNGs (that includes v1.18 - PNGs added in 1.6.1 IIRC). I recommend using a shell call to a small app, since compiling Image::Magick can get tricky. Using the LZW algorithm without permission is illegal (but who am I to send out the dogs), consult the Image::Magick manuals if you indeed wish to build THAT. Consult the manpages/docs of the application if you intend to use a shell call.

Short answer:I doubt there is an easy way of doing that.

Greetz
Beatnik
... Quidquid perl dictum sit, altum viditur.