resizing image files.

I need to read in some JPEG files (and perhaps GIF, PNG),  size them 
down, possibly crop, and save them back out again (possibly switching 
GIF to JPEG, vice versa) to a different path.


For some reason I am convinced that I used the LispWorks GP library to 
do this years ago when playing around with  LispWorks 4.  And, sure 
enough, it seems tantalizingly close. But I can't find my toy code from 
years back and I can't quite seem to find the functions I want in the LW 
docs.    Does anyone have any advice, pointers, or sample code?

I'm not using CAPI in my current project, and I do not need to display 
these images. Maybe that's my blind spot, perhaps what I'm looking for 
is there.  If anyone has  some guidance I'd appreciate it.

Chris


P.S. There seem to be quite a few different common lisp image libraries 
(ch-image, imago, etc.). I couldn't get ch-image to compile under LW5.  
Haven't looked at the others yet. If you know of one that'll work in 
LispWorks and do what I need, let me know.