I did find
this, Which has a few snippets of javascript that you might be able to integrate.
Actually, come to think of it, you can do this without javascript at all, purely via CSS; not sure why I didn't think of it because I am using a similar technique on my own web page for my navigation links.
Basically, you would end up with something like this:
<img src="blah/blah/image.png" class="displayimage">
hopefully your template uses the <img> tag for showing the images (assuming it's working as is). Then, you can have css in either a <style> tag or an existing css file:
.displayimage {
}
.displayimage:hover{
height: 200%;
width: 200%;
}
which would expand the image to twice it's size when you rollover it. It doesn't expand "smoothly" though, which might be the effect you want. For that, I would think you would need jQuery, or some other sort of client-side interaction.
I did find
a StackOverFlow question that has an answer for that, as well.