The disappearing jacket

Oliver was wearing a green jacket - and this causes problems in photographic setups that use “green screen” or, more properly, “chroma-key” effects. This technique is used to replace the background in a photo with a special background. Below is an illustration of this technique, taken from Wikipedia.

The practicality of green-screen compositing is demonstrated by actor Iman Crosson in a self-produced video. Top panel: A frame in a full-motion video shot in the actor's living room.[1] Bottom panel: The corresponding frame in the final version in which the actor impersonates Barack Obama "appearing" outside the White House's East Room.

In our case, the “real” photo was our group standing in front of a green wall. The photographer then replaced all green parts of the photo with a stock photo of the Seattle skyline! (A hint to this solution is that the Space Needle can be seen in the stock photo!) A second, minor mistero: Look again at the photo - part of Oliver’s green jacket was not replaced….why do you think that was the case?