Exif / Comment data - keeping it from the orginial or setting new values

We want to be able to have custom comment fields on the images served up by imagecache and alike.

Currently we use jhead (http://www.sentex.net/~mwandel/jhead/) to set the values on the original image just after its uploaded (via nodeapi), but when its re-sized/manipulated by modules using imageapi it looses these extra bits of meta data.

So ideally, there would be an option to keep the original meta data intact during manipulation, or if thats not doable, then some kind of post save hook, that means we could run jhead on the resulting image, re-adding the data we want, or cloning it from the original image.

Many thanks for any tips, pointers or even code!

a_c_m