04 March 2017

There are NO red pixels in this picture


Your brain sees the objects being bathed in blue light, so it compensates by adding a red that is not there.  The fact that the objects are strawberries accentuates the illusion, but is not a necessary feature.

Further discussion and explanation (and a photo with the "red" sampled to show that it is actually grey) at the source article in Vice's Motherboard.

4 comments:

  1. Only true in the strictest sense that there are no completely red pixels. There are colors that include red in the RGB mix, and that has a red tint even if you blur the image beyond recognition. There's also a perception thing going on with the expectation of red strawberries making them seem redder, but even a normal light photo of red strawberries won't have RGB 255,0,0 pixels.

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    Replies
    1. > and that has a red tint even if you blur the image beyond recognition.

      Nope. A red tint would only be there if the proportion of red in a pixel were higher than that of green or blue. Which is never the case in this picture.

      You can try it in Pixlr: load the image, color-pick the "reddest" area you can find, then click on the color square at the bottom left to open the color selector window, and you'll find that the value for R is never higher than that for G or B.

      A very neat illusion indeed!

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    2. This comment was mailed to me by a reader who couldn't log on to post the comment:


      Yeah, blogdpoy still forwards me to .se so the comment form will just not work. It's a pretty annoying but... I tried the solution I sent you last time (more than a year ago! :D) on my own blogspot account and it worked fine.

      Even if they forward to .se for me as I'm in Sweden it goes back to .com, If you need any help with this just give me a holler, it was quite easy and is easily reversible. I can even make a video guide if that's necessary ;)

      On to the post: http://tywkiwdbi.blogspot.se/2017/03/there-are-no-red-pixels-in-this-picture.html

      I saw this on Twitter and experimented a bit myself (starts here). It's easy to create these by crushing the channels above or under the center line of the curve adjustment in Photoshop. In this case it puts blue and green above the center, and red works in the negative.

      One thing I think many forget is that while the strawberries are gray in the image file as the channels can at the most reach neutral gray (top of red, bottom of green and blue), a screen will actually light up red subpixels in any gray color except pure black. So even if it's not supposed to contain red, we cannot say that it physically doesn't if we display the picture on a computer monitor :)

      That's it for me! Again don't hesitate if you want to try the fix, if it's any comfort I work as an app and web developer so I might have a clue what I'm doing ;)

      Cheers!

      //Andreas

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    3. Andreas, sorry to disappoint you. I don't feel comfortable trying to change the template of the blog. If I do something wrong, I wouldn't have a clue how to fix it.

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