Hi Mike,
I'm not getting the effect here - so it may be related to your "variable method" - or it may be related to your browser. first thing is to determine which, so...
a) open example 26 (File Upload) as this is an example of images in a browse. You'll need to change the browse to page-loaded, and server-side-sorting.
check if the same effect happens to you there. (if it does we need to investigate the browser version further.)
b) assuming (a) is all ok, we turn our attention to your method for letting the user set the width and height. Are you loading them direct from a file? If so make sure they're in the VIEW (ie add them to the hot fields). If you are setting them from a variable make sure it's a Session Variable, not a Value, and not a local variable.
Cheers
Bruce