Transparency and the sliding rings

This is a version of Stuart Anstis's sliding rings effect. Here Stuart and I add luminance values at the overlapping intersections that affect the apparent transparency of the rings. When the intersections are inconsistent with transparency, the rings appear to stick to each other, linked by the light intersections. When the intersections are dimmer, appropriately for transparency, the rings no longer stick but slide over each other. Note that the luminance contrast of the intersections is the same in both cases but of opposite sign: they are either brighter than the rings (no transparency) or dimmer (transparency). This tells us that the sticking is not driven by low level signals but by the high level interpretation of the rings and their material.