Constrain image size to container

[Magicgate Software - Skip Kimpel]

I am pulling images from an online database but need the images to
constrain to proportion and also stay within a certain size framework.  I
have no control over the size of the images I am pulling otherwise I would
just re-size everything.

I am currently using this to accomplish the image retrieval:
set the filename of image "imagelink" to "http://www.mysite.com/imgch.jpg"

Any help is greatly appreciated!