Hm... I was thinking, if a light source like the sun were to hit a black umbrella, a shadow would be cast upon the object beneath it. However, if the light source was a strong and direct one like a spotlight, and it struck an opaque source like a red umbrella, would the umbrella then act as a light source? Or would there be like red shadows.. (if there is such a thing o_o;;?) Or .. like, if there were blue shadows and a red light source, would those intersecting points be purple shadows then?