Boffins' five eyes surprise: Bees correct colour for ambient light

Three eyes look at the sky

Camera designers will get to add a technique borrowed from nature to improve how they handle colour, courtesy of the humble honey bee.

Boffins at Australia's RMIT University in Melbourne (with colleagues from Monash and Deakin Universities and the University of Melbourne) looked at how honey bees process colour information, and found some of their five eyes sense ambient light.

It turns out that three eyes (ocelli – simple eyes in invertebrates) on top of bees' heads are aimed directly at the sky, with two colour receptors designed to sense the colour of ambient light.

That helps honey bees do something that your camera has trouble with: adjust their perception of the colour of an object to take into account the amount of sunlight.

In other words, what they perceive from the two compound eyes that look at flowers gets adjusted so a flower appears as the same colour, whether it's bright sunlight or a cloudy day.

To demonstrate that the ocelli are part of the insects' colour processing, the RMIT team, led by the university's professor Adrian Dyer, “mapped the neural tracings from ocelli and showed neural projection did indeed feed to the key colour processing areas of the bee brain”, the university's announcement says.

For honey bees, enhanced colour sensing is a survival trait: it means that they don't miss high-yield flowers because the lighting on their first visit was different to their next.

Dyer believes the same kind of correction can be applied to imaging systems to enable accurate colour interpretation, and as Deakin University's John Endler said, it's also a way to make colour constancy cheap in computational terms.

Their work has been published at PNAS. ®

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