#100: Road safety ‘movie’

The Schyns Illusion enables the creation of ‘hybrid images’ in which elements of two different pictures may be superimposed to create a new one.

When viewed at different distances, the hybrid image looks like one or other of the two originals. An example is provided here in which a single image of a human face is shown as it would appear to observers at two different distances (and rescaled so that both views of the image are shown at the same size). It undergoes a radical change in expression from angry to calm.


This technique can be used to superimpose more than two original images. This would allow someone approaching a single image, printed cheaply in the traditional way, to perceive a short sequence of different views (without any need for animation equipment).

Obvious applications for this would be as an alternative to the costly electronic billboards used in outdoor advertising. You could create a crude, walk-by movie consisting of several superimposed scenes, each of which only becomes visible at the right distance from the poster.

Today’s invention is even simpler, however. Imagine a printed poster placed on a pedestrian crossing and visible to children as they are about to cross the road. The poster would carry the face of a trusted sports start or tv ‘personality’ (I’d tolerate even more ubiquitous narcissism if it can save lives).

As the child begins to cross the road, the face appears to look left, right and then left again and continues doing so throughout the road crossing.

So that’s the first 100 inventions. Why don’t we celebrate by funding a few thousand posters and getting them independently evaluated?

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