Quote: Hmmm... strange. If you added the blurred picture why there are dark seams around the balls? By adding everything should only get brighter, not more dark.
I was wondering about that also, but the explanation is pretty simple: when the blur passes are ran, they are ran for the whole scene, that is, for the black parts also. So this creates a "black border" around the balls which is then added to the final result. The catch is here: the area surrounding the border is brighter than the black border itself, so at the black border area, less color gets added, and on the bright area, more color gets in.
