I'll Address The Color Of A Dress

The internet started freaking out this week over the color of a dress after a woman posted a picture with the caption:

guys please help me - is this dress white and gold, or blue and black? Me and my friends can’t agree
— Swiked, Tumblr
Is it blue and black or white and gold?!?

Is it blue and black or white and gold?!?

Wired wrote up a great article explaining just why some people see the dress as blue and why some people see the dress as white.

Light enters the eye through the lens—different wavelengths corresponding to different colors. The light hits the retina in the back of the eye where pigments fire up neural connections to the visual cortex, the part of the brain that processes those signals into an image
— Adam Rogers, Wired.com

So our brain interprets different wavelengths as color when light bounces off objects. That in itself is not that interesting. The more interesting thing is how our brains interpret changing lighting and auto white balances what we see. Think about it. If you had a white sheet hanging outside, it would look different depending on what time of day it was and how the sun is positioned. At high noon in a clear bright day, the sheet might appear bright white, and at sunset the sheet might appear reddish orange, but our brain takes the environment into consideration and auto white balances what we see--we know that sheet is not actually red when we look at it during sunset. If you look at it long enough, it looks white to us. This phenomenon was described in the Wired article

Color temperature vs. time of day

Color temperature vs. time of day

What’s happening here is your visual system is looking at this thing, and you’re trying to discount the chromatic bias of the daylight axis
— Bevil Conway, Wellesley College.
The original image is in the middle. At left, white-balanced as if the dress is white-gold. At right, white-balanced to blue-black.

The original image is in the middle. At left, white-balanced as if the dress is white-gold. At right, white-balanced to blue-black.

The main thing I learned about this phenomenon this week is how important context is when it comes to our interpretation of color. We have certain expectations about how things should look depending on if it is day or night, a "chromatic bias" and it is important when coloring video to take these principles into account so you can do the best color grade possible.