The good news is you can definitely do this. If you have images on your server either in the file system or the database, then you won't need to use GD to generate them.
The most important part is setting the header information with the header function like:
header("Content-type: img/jpg");
All you need to do then is output the particular image file. This can be done by reading in the image file and immediately printing it out, or by querying the database for the image and outputting it.
Obviously your friend can pass in parameters or whatever which would determine what image is sent back.
Hopefully this helps.
Dave
