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Posted by: stevesliva Feb 27 2015, 06:33 PM

Some of you perhaps saw the internet blow up because people realized their perception of color in an image had nothing to do with the colors of the pixels.
There's a http://www.vox.com/2015/2/27/8119901/explain-color-dress, along with some great discussion of why the mind uses perceived illumination to determine the "true color" (dun-dun-duuuun) of the object in the photograph.

This all brought back to mind http://www.unmannedspaceflight.com/index.php?showtopic=7418&st=360&p=207836&#entry207836. I called the brain's adjustment a "ski goggle effect."

It's interesting that so simple a case could illustrate that what your brain decides to do with Mars illumination. Should you ever go there and walk around with a transparent globe on your head you may perceive a lot more color and contrast than you would perceive on Mars looking out the window of a white spacecraft interior dimly lit with broad spectrum light... so with images, that begs the question: do I make this a window, or make it immersive?

Posted by: Gerald Feb 28 2015, 02:03 PM

The simple "truth" is, that the dress is neither blue and black nor white and gold; it's blue and gold in the image. Here an enhanced version:

The flaw is the prejudice, that the suggested options are the only ones.

... And the camera may have reproduced colors not properly.

Posted by: dvandorn Feb 28 2015, 04:49 PM

From what I have read, the dark trim on the dress is actually black and the ambient lighting provides the gold tint via surface reflection. So, even with image manipulation, you still get colors that aren't actually inherent in the subject. Interesting!

-the other Doug

Posted by: Floyd Feb 28 2015, 05:56 PM

xkcd even has jumped into the debate http://xkcd.com/1492/ as a optical white balance example.

Posted by: ddeerrff Mar 1 2015, 02:24 AM

Then it is not black. "Black is.... the result of the absence of or complete absorption of light." (Wikipedia). If the trim was black, it would not be reflecting any ambient lighting.

Posted by: dvandorn Mar 1 2015, 05:03 AM

True. But fabrics are not judged by a physics definition of black bodies. A "black" fabric is simply relatively non-reflective, but under the right kind of lighting, and with the right kind of fabric (especially any kind with a soft or "roughened" surface, like velvet), it can reflect ambient light in such a way as to appear brownish, or reddish, or even bluish.

Under the Wikipedia definition, there really are no "black" fabrics or materials of any kind in our everyday life. Shine a bright light on any "black" item in your house, and you'll see.

-the other Doug