Blue and Gold Dress: Understanding the Optical Illusion Remember when the internet went absolutely nuts on the colour of a dress? The dress was blue and black. The original viral poster, Caitlin McNeill, later said it was a black and blue dress Exploring Color Constancy: The Dress Phenomenon Explained Remember "The Dress Illusion"? The dress was a viral phenomenon on the Internet in 2015. Viewers of the image disagreed on whether the dress depicted in a photograph was coloured black and blue,