Countering the notion that colour is unimportant for human face recognition, MIT researchers have discovered that when images are blurry, the brain relies on colour cues to pinpoint identity.
For a long time, colour was not considered crucial in recognising faces because in experiments, people tended to identify accurately faces that were artificially coloured, even in hot pink and electric blue.
In this latest study, Pawan Sinha, assistant professor of computation neuroscience at MIT, and Andrew W. Yip, a recent MIT graduate, found that when subjects look at images that are degraded – blurry or otherwise unclear – they actually do rely heavily on colour. In addition to checking hair or skin hue, the brain probably uses colour cues to determine where the hairline starts and ends, for example.
‘Colour cues do play an important role in face recognition,’ Sinha said. ‘Their contribution becomes evident when shape cues are degraded. [With blurry or faraway images], recognition performance with colour images is significantly better than with grey-scale images.’
In addition to helping understand the basic workings of the recognition processes in the brain, the research could lead to improved machine vision systems. Because the experimental stimuli used by Yip and Sinha mimics the appearance of human faces at a distance or of images taken with poor-quality cameras, the results also have implications for systems that attempt to recognise people videotaped by surveillance and security cameras. In previous work, Sinha developed software that, given blurry images, comes up with clearer pictures of what the original faces probably look like.
Other potential uses include better criminal identification kits that allow police artists to create sketches of crime suspects based on eyewitness descriptions.