CSS Optical Illusions(alvaromontoro.com)
224 pointsby ulrischa16 days ago13 comments
  • myfonj16 days ago
    These "dots appearing only while (not) focused" are known as "extinction illusions", namely

        "25 - Appearing Dots"
    is "McAnany's type" [1], and

        "26 - Disappearing Dots"
    is known as "Ninio's type" [2], according Akiyoshi Kitaoka's materials. (I have recreated them too few years ago [3][4], before getting to the source.)

    [1] https://www.psy.ritsumei.ac.jp/akitaoka/kieru3e.html#:~:text...

    [2] https://www.psy.ritsumei.ac.jp/akitaoka/kieru3e.html#:~:text...

    [3] https://codepen.io/myf/full/XjdmJy ( scintillation warning)

    [4] https://codepen.io/myf/full/jMqoMW ( scintillation warning)

  • hinkley15 days ago
    I thought this was going to go the other way.

    Worked on a project that wanted to make everything a different grayscale color. It was out of control already when someone one day complained that two pieces of text were a different color.

    They weren’t. They were identical. But they were on two different background colors which make the optical illusion that they weren’t. And I reminded them for the twentieth time that we were using too goddamned much gray.

  • smusamashah15 days ago
    This coca cola illusion is my favourite one https://gagadget.com/en/446542-a-photo-of-a-coca-cola-can-th...

    Coca cola appears red when no red at all is used in whole image

    • flexagoon15 days ago
      This is a great illusion, though I often see that people try to explain this (and a similar image of strawberries) as "our brain knows this object is supposed to be red so it fills in red", which is not what's happening - it's based on color contrast like many other optical illusions
    • mediumsmart14 days ago
      The background on the can is a very light red. I know from painting murals that a light color close up looks darker from some distance.
  • sandpaper2616 days ago
    This is cool, but more as a demonstration of interesting CSS techniques than optical illusions in my opinion.

    Also, interestingly, I seem to be able to force myself to "see through" all of these illusions except for induced gradients, which I can't stop seeing unless I cover part of the screen.

  • brandon_bot16 days ago
    Cool!

    I did something similar for my personal favorite illusion, the Ames window illusion. Recreated with CSS: https://brandondong.github.io/blog/ames_window/

  • 16 days ago
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  • nilslindemann16 days ago
    33 - color fan: There is another interesting optical illusion here: The fan seems to rotate faster when not directly looking at it.
  • andredurao15 days ago
    On #4 (White's Illusion) it looks like for me that the gray bar that is surrounded by black is brighter than the one surrounded by white instead of darker :#
  • aj715 days ago
    What would be most interesting is using optical illusions to help decode how brain visual processing is done.
  • encom16 days ago
    These are all super dark, for some reason.
    • christophilus16 days ago
      You have to actually run them. Otherwise, they're just a dark CodePen preview.
      • encom16 days ago
        Why the extra step of having to click each one? Only a few of them are interactive.
        • d-us-vb16 days ago
          Because codepens can run javascript. And if a page has 50 of them, it might make the page load time much longer. I know that all these examples are pure CSS, and maybe there is a setting in codepen to disable the "Run" button and automatically run it. Still, getting to decide is generally a better pattern than presuming that that's what the user wants, especially when the fact that the code is inside a codepen makes it explicitly not an integral function of the page. "I thought this was just a blog, and now you want me to run all this javascript??" -- some JS hater, probably.

          I appreciate getting to choose as much as possible when code runs.

          • zamadatix16 days ago
            Somewhat ironically, Codepen ended up introducing the JS execution requirement to view the content.
  • moralestapia16 days ago
    Wow, this is great!

    I want to put some of them in my UIs.

    • herpdyderp16 days ago
      I've often run into these unintentionally messing up my UIs!
  • layer816 days ago
    Heh, I used to do these in Excel.
  • eulgro16 days ago
    They could make capchas out of these.
    • hiccuphippo15 days ago
      "Please select the dancers spinning to the right"