# Does anyone know how the science behind this image? **URL:** \ **Category:** Factual Questions\ **Created:** [November 3, 2009, 10:33pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215 "2009-11-03T22:33:20Z")\ **Posts on this page:** 12\ **Page:** 2
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 4, 2009, 9:58pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/21 "2009-11-04T21:58:15Z")
The false colour illusion on the b/w image fades fast, but if you look completely away from the image, then suddenly back at the black dot, you may see it again - I did (not as strongly the second time). ---
**Author:** ![Bad\_Astronaut](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Bad\_Astronaut](https://boards.straightdope.com/u/Bad_Astronaut)\ **Post date:** [November 4, 2009, 11:18pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/22 "2009-11-04T23:18:53Z")
For the people that didn’t get it to work - it’s definitely worth it to go back and try again. Just make sure to stare intently at the black dot and don’t shift your gaze or move your head. I had seen these before and knew what to expect, but when it switched I saw such a vibrant, colourful image that I felt a sliver of doubt that the actual picture could really be B&W. I enjoyed it for a few seconds before shifting my gaze and ruining the illusion. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [November 5, 2009, 4:08am UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/23 "2009-11-05T04:08:14Z")
> [@The\_Hamster\_King](#): > > It’s not particularly well-designed. The text at the bottom encourages you to shift your gaze away from the dot when the picture changes to black and white, which ruins the effect. If you keep your gaze focused on the dot, you’ll see a color image of the scene instead of a black and white image. It really helps to cover the status bar, with your hand or with some object. The effect was much stronger for me after I did that. ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [November 5, 2009, 5:12pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/24 "2009-11-05T17:12:35Z")
Yes, and after the switch, you have to avoid your natural instinct to examine different parts of the photo. If you shift your gaze away from the dot to another part of the picture, the color effect is lost. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [November 5, 2009, 5:21pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/25 "2009-11-05T17:21:06Z")
The Spanish Castle one is infinitely more impressive - but make sure you read the instructions properly before trying it. ---
**Author:** ![Hypnagogic\_Jerk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hypnagogic_jerk/32/4252_2.png) [@Hypnagogic\_Jerk](https://boards.straightdope.com/u/Hypnagogic_Jerk)\ **Post date:** [November 5, 2009, 8:18pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/26 "2009-11-05T20:18:02Z")
> [@Ferret\_Herder](#): > > It really helps to cover the status bar, with your hand or with some object. The effect was much stronger for me after I did that. Interestingly enough, if you do this and then remove your hand when the black and white picture is shown, the part you used to cover appears blue. It did when I tried it anyway. ---
**Author:** ![MJinks](https://avatars.discourse-cdn.com/v4/letter/m/da6949/32.png) [@MJinks](https://boards.straightdope.com/u/MJinks)\ **Post date:** [November 5, 2009, 9:48pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/27 "2009-11-05T21:48:31Z")
I liked the Castle one. I found that if I refocussed on the dot after I’d looked away the colour would return. That lasted a good thirty seconds and I looked away at least half a dozen times. Neat. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [November 6, 2009, 7:42am UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/28 "2009-11-06T07:42:19Z")
> [@Hypnagogic\_Jerk](#): > > Interestingly enough, if you do this and then remove your hand when the black and white picture is shown, the part you used to cover appears blue. It did when I tried it anyway. Blue is the negative colour of the flesh color of your hand (thus I deduce that you’re Caucasian). ---
**Author:** ![Hypnagogic\_Jerk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hypnagogic_jerk/32/4252_2.png) [@Hypnagogic\_Jerk](https://boards.straightdope.com/u/Hypnagogic_Jerk)\ **Post date:** [November 6, 2009, 10:03am UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/29 "2009-11-06T10:03:36Z")
> [@jjimm](#): > > Blue is the negative colour of the flesh color of your hand (thus I deduce that you’re Caucasian). Yes, this is what I assumed, but I wasn’t sure. I am. ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [November 6, 2009, 11:01am UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/30 "2009-11-06T11:01:38Z")
> [@Mindfield](#): > > Afterimages appear in opposite, or **complimentary** colours… Oh, Red, you’re so warm and inviting. And Green, you’re looking very healthy today. My, Yellow, you have such a sunny personality… ---
**Author:** ![Sragde](https://avatars.discourse-cdn.com/v4/letter/s/a3d4f5/32.png) [@Sragde](https://boards.straightdope.com/u/Sragde)\ **Post date:** [November 6, 2009, 3:09pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/31 "2009-11-06T15:09:30Z")
It didn’t happened with me - I saw it black&white. I don’t know why, but these picture tricks never work with me. I see everything as it is. Can somebody explain why? ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [November 8, 2009, 10:24pm UTC](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215/32 "2009-11-08T22:24:02Z")
> [@Sragde](#): > > It didn’t happened with me - I saw it black&white. I don’t know why, but these picture tricks never work with me. I see everything as it is. Can somebody explain why? It could possibly be with you not being able to keep your eyes perfectly still throughout the entire thing. If your eyes wander around the image rather than stare fixedly at the black dot, you won’t get the after-image on your retina. That said, there may be other reasons too, but I don’t know enough to suggest what they might be. [Previous page](https://boards.straightdope.com/t/does-anyone-know-how-the-science-behind-this-image/516215.md?page=1)