I want is to modify the picture viewing mode to only allow the user to move to the next picture when there's a rating. 

Instead of a "next picture" button (or thumbnail), the viewer advances whenever the user enters a rating.  Keybindings for entering ratings would help a lot.

This will allow me to force users to rate the pictures.  I have thousands and thousands of pictures to rate.  Crowd-sourcing seems like the best way.

Can anyone help me find a way to do this? 

Thanks!