Appion

Norm image (what some called gain image) is typically calculated ahead because the complexity of dead pixel or hot pixel in a divide calculation need more calculation resource than a simple multiplication which will not fail mathmatically.

The frame correction in 9d5f18a3 calculates norm for every frame. It is not a good idea and should be changed.

If this can not resolved quickly, I recommend revert the call to the old one and fix this in a branch that does not affect beta nor release.