In this case, a photo of an old building was first loaded (a school building that has been closed and unused for many years).  The Set Background/Create Negative Stencil option was then selected.  That caused the picture to be set as the Mask Background, and also automatically created a 'negative' Stencil based on the photo.  The result being that the light areas, like the sunlit building face and the sky, became static and unchanging, while the darker portions, including silhouetted tree branches and shadowy places, remained changeable.  Another colorful image was then loaded and a Kaleider Split Triangle Funnel was rendered to produce this odd picture mixture.
Kaleider Building Mask