(Credit: Rob Jenkins and Christie Kerr)
The human eye is capable of reflecting other people's faces in high enough resolution that they can be identified. But there are a few caveats.
There's an old superstition that the eye of a deceased person retains an image of the last thing they saw before dying. It isn't, of course, true — but researchers at the University of York and the University of Glasgow, UK, might have found the next best thing.
Rob Jenkins and Christie Kerr have published a paper that describes how they were able to recover identifiable images of people from a photographed subject's corneal reflections.
Jenkins and Kerr used a high-resolution 39-megapixel camera and Bowens flashlamps, then stood four bystanders and the photographer in a semicircle outside the range of the camera lens. In the resulting 7200x5400-pixel image, the subject's iris has an area of about 54,000 pixels.
They then showed these images to volunteers, who were able to identify them as human faces — for people who weren't familiar with the bystanders, they did this with 71 per cent accuracy. Volunteers who were familiar with the bystanders correctly identified the images as human faces with 84 per cent accuracy.
In a second experiment, a group of volunteers, each of whom was familiar with only one of the bystanders, was asked if they could identify anyone in the images. They did so with a 90 per cent accuracy rate.
The experiment sounds like something out of a fictional crime procedural, and it may not, in fact, have much real-world application yet: the set-up was very controlled. This is a limitation Jenkins and Kerr freely acknowledge. However, they said the technique could be used to combine pairs of images recovered from a subject's two eyes to create a 3D representation of the subject's surroundings.
They also note that, in a few years' time, mobile phones could very well have 39-megapixel and higher resolution cameras — but until then perhaps it could be employed at lower resolutions.
"For crimes in which the victims are photographed (eg, hostage taking, child sex abuse), reflections in the eyes of the photographic subject could help to identify perpetrators," they said.
The full paper can be read online in the journal PLOS One.