Hi Kristian, I'd make fun2 a virtual method in the CAlpha, to avoid the need to do what you are doing. But I understand that this is a simplified example to express the concept, and not a particular situation, so my initial response may not be relevant. To me there is no difference between using dynamic casts, and using the pixelTypes technique. Both suffer from lack-of-encapsulation. Sincerely, --Eljay
