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Displays and Projectors
: The Dress – Solved?
The Dress – Solved?
5 years ago
(February 28, 2015 01:53 AM)
Member since July 2013
If you haven't seen "the dress" on TV or the Internet, you must be on vacation or something. Essentially it's a photo of a dress that appears to magically change colors, between blue and black to white and gold...and back again. Man in the street interviews show different people viewing the same image on the same device having different opinions on what the colors are. Some people report the dress changing colors
as they watch it
. Numerous "experts" say that it's all about how the human brain processes information.
I've figured it out. It's an optical illusion made possible by how LCD displays work. LCDs produce false color when viewed anywhere different than head-on. They've improved to the point that we have forgotten this, but with the right combination of manual and/or automatic contrast/brightness settings, the photo of the dress is more prone to produce a false color image off-axis.
How do I know this? When I first saw the photo, one of the first things I did was look for some part of the picture that was likely to be monochrome white. I found one, and used that as my white reference. The dress was blue/black then. Later in the day I saw what looked like the same photo of the dress, but it was white/gold. I was baffled until I looked at my white reference, and noticed that it was washed out in comparison to the first photo I saw. At first I thought it was simply a case of someone crafty sending out two identical posts with two different photos, but that doesn't explain when people see different things while viewing the same photo! When I saw people on the street at comparatively different angles from what was often a 5" smartphone screen simultaneously see different things, I knew it had to have something with polarization. It had to be the LCD screen that most people were using!
For those who don't know, LCD screens work by twisting microscopic molecules. A little twist makes a LCD pixel less bright, and the full twist makes it opaque. It's this trait that has caused obvious aberrations in the picture of early LCD displays. Circularly polarized light can pass through more twist than linear polarization light before it gets darkened. Mystery solved!
Or is it?
If you are interested in "the dress" and have something other than an LCD display to view it on, give it a try and see what you see. I'd be interested in an answer from you!