Eyes are supposed to be windows to the soul -- but they make even better mirrors.
And what they reflect will astonish you.
Researchers studying the incredible level of detail in modern digital photographs were able to pick out the tiny reflections of faces hidden in the eyes of the subject. By zooming in on the subject’s eyes in high-resolution, passport-style photographs, they were able to pick out the faces and accurately identify them.
“The pupil of the eye is like a black mirror,” said Rob Jenkins, of the Department of Psychology at the University of York. “To enhance the image, you have to zoom in and adjust the contrast. A face image that is recovered from a reflection in the subject’s eye is about 30,000 times smaller than the subject’s face.”
Working with Christie Kerr, of the School of Psychology, University of Glasgow, Jenkins recovered the images of bystanders that were as small as 27 pixels across (1 megapixel is about a million pixels). Yet when presented to panelists in a face-matching task, observers were able to match the diminutive faces 71 percent of the time. When the faces were familiar ones, people recognized identity correctly 84 percent of the time.
“Our findings thus highlight the remarkable robustness of human face recognition, as well as the untapped potential of high-resolution photography,” Jenkins said.
The pictures were taken with a high-end, 39-megapixel Hasselblad camera, snapped while the onlookers were close to the subject and the room well lit. But with smartphones that pack increasingly better digital sensors, even ordinary photos may soon capture a similar level of detail.
The Nokia Lumia 1020 has a 41-megapixel camera, for example; AT&T sells the phone for just $199.99.
The researchers say that in crimes in which the victims are photographed, such as hostage taking or child sex abuse, reflections in the eyes of the photographic subject could help to identify perpetrators.
Images of people retrieved from cameras seized as evidence during criminal investigations may be used to piece together networks of associates or to link individuals to particular locations.
They published their work in the open access journal PLoS ONE.