Baran, IlyaKeller, PhilippBradley, DerekCoros, StelianJarosz, WojciechNowrouzezahrai, DerekGross, MarkusP. Cignoni and T. Ertl2015-02-282015-02-2820121467-8659https://doi.org/10.1111/j.1467-8659.2012.03039.xWe present a practical and inexpensive method for creating physical objects that cast different color shadow images when illuminated by prescribed lighting configurations. The input to our system is a number of lighting configurations and corresponding desired shadow images. Our approach computes attenuation masks, which are then printed on transparent materials and stacked to form a single multi-layer attenuator. When illuminated with the input lighting configurations, this multi-layer attenuator casts the prescribed color shadow images. Alternatively, our method can compute layers so that their permutations produce different prescribed shadow images under fixed lighting. Each multi-layer attenuator is quick and inexpensive to produce, can generate multiple full-color shadows, and can be designed to respond to different types of natural or synthetic lighting setups. We illustrate the effectiveness of our multi-layer attenuators in simulation and in reality, with the sun as a light source.10.1111/j.1467-8659.2012.03039.x