A few years ago at one of our local theatres, the set incorporated a pattern painted onto the floor, which was then painted over with black. In one light, the floor appeared just plain black, but in another, the pattern could be seen amazingly...
Does anyone know how this can be achieved?
For example, if your floor had a checker board of red and green squares and you light it with primary blue, the floor will appear black. If you light it with primary red only the red squares will appear. If you light it with primary green only the green squares will appear.
If you light it with both Primary red and green or white, both sets of squares will appear.