Those two images above — what do you see? They're clearly different, right? They're the same thing.
I first saw it in a retweet from Business Insider's Steve Kovach this afternoon, and I have to admit it's a little strange: in TweetDeck's preview, for instance, the nails and lips appear pink, but if you open the image up in its own window, they're very dark red.
Click on the image below — which originally appears in the Tumblr site Totally Transparent by Stanley Green — in a few different browsers. You'll see it.
There's a less subjective explanation for this one than for #TheDress, though: it depends on how the application you're using to view the image treats transparency.
In addition to specifying red, green, and blue pixels for each dot of an image, some image formats can also specify a transparency value that determines how much you can see through the pixel to whatever is behind it. The problem is that when there's no other image behind a transparent area, different programs treat transparency differently —sometimes the see-through areas are rendered white, other times black.
This image takes advantage of that phenomenon: the lips and nails actually just have a tiny bit of red applied to them, but they're mostly transparent. Depending on the app that is rendering the lips and nails, the transparent areas are rendered as white — making the features pink — or black, making them a deep burgundy. In other words, unlike #TheDress, this confusion is totally intentional.
Here's what happens if you look at the original image in Photoshop, which uses a checkerboard pattern to indicate see-through areas:
It's a neat trick, and it's one that you can probably confuse your friends with (before they see this post, anyway). Go ahead!
Update March 13th, 4:32PM ET: Business Insider's Caroline Moss notes that Business Insider's Steve Kovach should not have been hat-tipped. We apologize for the error.
Update March 16th, 12:52PM ET: The artist of the original image, Stanley Green, has contacted us. We've added a note that it comes from his Tumblr site, Totally Transparent.