Image layout - size calculator

I'm not sure if there is a word for this type of image layout, but it's pretty common - one large image to the left, with two smaller images tiled vertically to the right, like an old window.

I needed to show a client some different options for image sizes, so I put this calculator together quickly to show some examples.

The images come from the excellent Lorem Pixel, and the slideshow uses the jQuery cycle plugin.