It's a white dress with golden/brown accents lit by a cold blue light from behind the camera. That messes with people's perception of color since the store see

It's a white dress with golden/brown accents lit by a cold blue light from behind the camera. That messes with people's perception of color since the store seen in the background is lit by a warm light. People who see it as blue are intuitively correcting for the light of the background. It's a simple optical illusion easy to replicate: http://www.michaelbach.de/ot/col-context/index.html http://www.michaelbach.de/ot/col-context/index.html