if your picture size is 200x400 pixels, then on screen, u'll want to be 150 high (to match other pictures), so the width will be 200 * (150/400) = 75 ; ie : u reduced both width & height down to 37.5% .
If you don't understand, just enter anything for RealSize & when u'll see result on screen, u should begin to get it...
And yup, normally, demo users shouldn't mod the game (according to the EULA), but it's ok, for little things, I don't care much...
