01 May 2014

Don't believe everything you "see"

To move the slider you need to visit the image source at eChalk, where there are two additional color illusions.  I tried to verify the illuson by taking screencaps of the two squares:

The differences are minimized but not eliminated.  Perhaps there is also a factor introduced by my monitor's color rendering and screen resolution.


  1. You are right, the one on the top is a bit darker, by about 6%. Though there a good examples of this kind of illusion out there (and i believe you already had similar ones on this blog), this is not one of them.

  2. Being a web designer, I happen to have a browser plugin installed that allows me to use an eyedropper tool to pull the color from each of the boxes.

    The top box is rgb(128, 73, 14) or #80490E the bottom box is rgb(128, 13, 14) or #80490E.

    These are identical, but moving the mouse around reveals slight variations in the colors in the boxes due to noise in the picture.

    1. Thank you, Koleslaw (and we'll assume your "73 vs 13" is a typo, so no need to correct it). I appreciate your technical expertise.

  3. Also be aware that the screencaps you posted are JPEG compressed. The compression algorithm is lossy and therefore the images are not perfectly accurate. Image compression algorithms like this are usually tweaked to lose those details that are least noticeable to the human eye, so misrepresenting colors that the human eye is supposed to misidentify could be considered as intended functionality. For precise comparisons you should use lossless image formats, like raw bitmap (BMP) or PNG.

    Technicalities aside, here's a TED talk by the author of those illusion images for some broader context about what it tells about us: http://www.ted.com/talks/beau_lotto_optical_illusions_show_how_we_see

  4. Don't know if there's a code to be able to post pics. HTML didn't seem to work. But I screen capped and photoshopped the two boxes together and they visually seemed to match.


    It's not a great example. I was twisting and turning the block to make it feel more aesthetically pleasing. So if someone is wondering why the top block that I pasted in doesn't match the original, that's why.


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