For the effect to be guaranteed must carefully watch the red dot on the image nose . Then look at a white surface – a sheet of paper, for example. You should see the color version of the image.
Here’s how it works: If you look for long an object, eye photoreceptors – especially cone cells – lose sensitivity due to the effort. And when this effort after watching a white surface, cone cells send signals much stronger. The brain interprets this discrepancy as you look at the colors in the image opposite. In other words, rather than see “negative” picture, you have the impression that look for color version of the image!