Red strawberries with no red in them
How your eyes find red in a picture that has none.
How this site works. Every fact is in our own words and linked to its source, beside it. Where good sources disagree, we show each version in a “Sources differ” box. Every picture is our own drawing: we don’t copy the famous originals, we make our own versions of the idea.
The picture
Akiyoshi Kitaoka’s famous picture shows a strawberry tartlet with a blue-green tint, and yet the strawberries still look red. Michael Bach
There is not a single red, or even reddish, pixel in it. Michael Bach
Kitaoka made it in 2015, and Bach calls it a strong demonstration of colour constancy. Michael Bach
How can that be?
The mostly green-blue picture shifts what your eye takes as white, so grey and white areas look reddish. Michael Bach
Mask off just the ‘reddest’ parts and the red mostly disappears. Michael Bach
Swap the strawberries for ovals of the same colours and the ovals still look reddish, so it isn’t only that we know strawberries are red. Michael Bach
Expectation does play some part: there is evidence that it affects colour perception to some degree. Michael Bach
Colour constancy
Your visual system tries to work out the colour of the light and ‘subtract’ it. This is called colour constancy, and it usually works well. Michael Bach
That is why a photo taken on a glacier at noon can look surprisingly blue when you look at it at home. Michael Bach
Our view: your brain isn’t being fooled here so much as being clever in the wrong picture. In real life, a blue light on a strawberry does not make it stop being red.
Next: contrast and shadows →