Question: Is this dress white and gold, or blue and black?
How can two people look at a photograph of the same dress and see different colors?
Click to see the full-size dress image
It all started when a Tumblr user named Swiked posted a picture of a dress on the Internet on Feb 25, 2015 and asked, "Guys please help me - is this dress white and gold, or blue and black? Me and my friends can't agree and we are freaking *** out." The internet nearly collapsed that night and the following day over the debate about the color of a dress. Many celebrities have tweeted their views. Millions of the commoners have joined in via Facebook and other forms of social media. The dress has been mentioned online more than 20 million times. The Ellen Show picked up on it, saying on Instagram that "From this day on, the world will be divided into two people: blue and black, or white and gold."
Answer: In reality, it is indisputably blue and black dress from a British company called Roman.
What is going on?
First of all, the dress image that we see on swiked.tumblr.com is the image in the middle. The dress color of this image is actually seen by most people as pale blue-dark gold and quite different from the original dress which is blue-black. Apparently, Swiked's friend, who took the picture, is no photographer and the image she took is over-exposed and the lighting conditions have something to do with this. You can use Photoshop to brighten up the image to make it white-gold as seen in the image on the left or darken it to regain original color as seen in the image on the right. And indeed, several demonstrations on Internet and Youtube have shown that by tilting your computer screen, thus changing the brightness of the screen, can change the perception of the dress's colors
Now, the second question: Why two people look at the same image in the middle and see different colors?
One group see the color as white-gold resembling the image on the left and another group see the color as blue-black resembling the image on the right. Why?
There are two types of photoreceptor cells in the retina. Cone cells are responsible for color vision as well as eye color sensitivity; they are less sensitive to light than the rod cells and function best in relatively bright light, as opposed to rod cells that work better in dim light. At very low light levels, visual experience is based solely on the rod signal. This explains why colors cannot be seen at low light levels.
Cones are normally one of the three types, each with different pigment, namely: S-cones, M-cones and L-cones. Each cone is therefore sensitive to visible wavelengths of light that correspond to short-wavelength, medium-wavelength and long-wavelength light. In layman's term, the cones cells are color sensitive, specifically to red, green and blue.
Because humans usually have three kinds of cones with different photopsins, which have different response curves and thus respond to variation in colour in different ways, we have trichromatic vision. The three pigments responsible for detecting light have been shown to vary in their exact chemical composition due to genetic variation; different individuals will have cones with different color sensitivity. This may explain why people perceive the dress color differently.
Why the same person may see the dress color differently at different times?
An interesting effect occurs when staring at a particular color for too long. Such action leads to an exhaustion of the cone cells that respond to that color - resulting in the afterimage. This vivid color aftereffect can last for a minute or more. For those who see the dress as blue-black, if you have looked at the dress for a long period of time or exposed to blue color somewhere else, the dress color may turn into white-gold.
Stare at the center of the blue circle for 60 seconds, and afterward switch your view to dress below. The dress color within the view will turn into white-gold. If you do this repeatedly, the whole dress may also change its color.
There are three types of cone cells in the retina and each contains photopsin specifically for red, green or blue color. (Photopsins are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision.) Those who see the dress color as white-gold have fewer blue color-sensitive cone cells and/or lesser amount of the specific photopsin. The similar effect can be demonstrated by a prolonged exposure of eyes to blue color which temporarily deplete the specific photopsin.