Big image pricing rule

Hello,

When i try to make a pricing rule for an image that is bigger as 500px it seems to just set the product price to the price i used in the pricing rule. Like when i set the pricing rule to €20 and i use a big image it makes the product price €20. Is it possible to have the €20 added on top of the products price. So if the product costs €10 and the pricing rule is €20 i would like to see €30 when i add the big image.