CSS Transitions problem

[DbDHost]

Part of a project I am working on is an image gallery.
I am using the mouseover event to change the source of the current image and apply a CSS transition filter to it. All this works great. When a user mouses over a thumb the larger image fades out and the new image fades in beautifully. My problem is that the final image is very pixelated.

Has anybody else had a similar problem with CSS transitions and images?
Here is a screenshot of my page after the transition has been applied to an image. (http://dbdhosting.com/Robert/Transition.htm)

[DbDHost]

I'm a little embaressed to admit it but I figured out what the problem was.
My script was changing the source of the portrait to the source of the thumb. So the thumb was being displayed with the dimensions of its portrait.

Dohh, it's the little things that get me more often than anything else :).