[Plugin: NextGEN Gallery] Random image width/height

Hi there,

I’m using the random image shortcode to display a random image on my frontpage.
It uses the settings from the thumbnails, but I would like to assign it a width and height of my own.

I’ve already tried [ random max=1 w=500 h=500 ], but doesnt work at all.
How can I adjust the width and the height of this single image?

regards,
tim