Eye of the beholder: In rare photo, some see dress as black and blue, others as gold and white

Shop manager Debbie Armstrong adjusts a two tone dress in a window display of a shop in Lichfield, England, Friday Feb. .27, 2015. It's the dress that's beating the Internet black and blue. Or should that be gold and white? Friends and co-workers worldwide are debating the true hues of a royal blue dress with black lace that, to many an eye, transforms in one photograph into gold and white (AP Photo/Rui Vieira) (The Associated Press)

The two-tone dress, left, alongside an ivory and black version, made by Roman Originals, that has sparked a global debate on Twitter over what colour it is on display in Birmingham, England Friday, Feb. 27, 2015. It's the dress that's beating the Internet black and blue. Or should that be gold and white? Friends and co-workers worldwide are debating the true hues of a royal blue dress with black lace that, to many an eye, transforms in one photograph into gold and white. (AP Photo/PA. Joe Giddens) UNITED KINGDOM OUT: NO SALES: NO ARCHIVE: (The Associated Press)

It's the dress that's beating the Internet black and blue. Or should that be gold and white?

Friends and co-workers worldwide are debating the true hues of a royal blue dress with black lace that, to many an eye, transforms in one photograph into gold and white.

Optometry experts are calling the photo a one-in-a-million shot that perfectly captures how people's brains perceive color and contrast in dramatically different ways.

Those who subconsciously seek detail in the dress' many horizontal black lines convert them to a golden hue, while the blue disappears into a blown-out white. Experts say the photo's exceptionally warm yellow backlighting triggers this alternative perception.

The English dress retailer, Roman Originals, has reported a million hits on its sales site since the photo's worldwide distribution Thursday night.