Category Archives: experiments

My eyes! My eyes!

This is the eye-candy equivalent of munching too many wham bars. It's so simple I can't help but love it, cheesy as it is.

Before I explain what's going on - although you can probably guess - have a go at staring at the applet below. If there's a big "P" then it's still loading. If there's no applet... well, email me your browser, etc, etc and I'll try and fix it.


  1. Get really close to the screen
  2. Stare at the flashing square in the middle of the crazy-colour image. Don't blink or move your eyes!
  3. Count a good few flashes. 8-10 flashes should give you a good burn-in.
  4. Click the mouse button
  5. :O !
  6. Rinse and repeat

Processing-based Java applet:

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The effect can last for a surprising amount of time, providing you keep your eyes completely fixed on the square. The second you move them, something in your eyes and brain puts the internal window screen wipers on and it's lost. At least for me, it seems that holding a fixed-view is more important than the length of time you stare. You can get a reasonable after image from a pretty quick glance providing you don't look around the screen.

Most people are familiar with "persistence of vision", as it's known, through looking at light bulbs for too long, their tellies refresh rate, helicopter blades turning into a blur, and cool gadgets like this. It's likely that the colour burn-in aspect of POV doesn't have quite as many real applications as the "things moving too quick to see" aspect, so I expect the applet above will come as a happy surprise to at least a few people.

Question is: Is it useful? Well, I reckon it might be in the right setting, but for someone working in graphics/lighting it's at least something to be aware of. I was shown this effect by Jeremy Vickery, an ex-Pixar lighting artist while on a visit to Geomerics, so I'd expect the film industry is already well aware of it. He demoed it to us in a regular powerpoint slide as one of several examples of how crazy and unpredictable your eyes/brain can be. You eyes just lie, frankly. If you are interested you can get further details from his DVD and likely find his GDC "Practical Light and Color" talk slides on the net.

The question is, can this effect be used to good effect in games/films? I'm open minded to this possibility, but still thinking about it. There are definitely other tricks-of-the-eye that are relevant to film makers. In films you have robust control over what comes next. Games? Maybe. Still thinking.