Make it possible to choose the image size for to full size view

I like the zooming feature of lightbox2, but there is a reason I can't use it. The "orginal" size of my images are a lot bigger than the size in that I wanna show in the images (e.g. they should be 1600x1200 in full view and not 3296x2472). It would be nice to add an option to choose which image size from the image settings to use.