Debunking TV technology: Reflections in the cornea

Same old TV adage, take a low resolution image, and extract a wonderfully enhanced image from a reflection in someones cornea. Easy to debunk right? Not so. It is possible to get an image from someone’s cornea, but not from a great distance, and there lies the debunk.

The process of extracting an image from a reflection in a persons eye is known as corneal imaging. CSI New York use it in one of their episodes (S1: Night, Mother). The team use footage from a CCTV camera, and extract an image from the reflection in the woman’s cornea. First the image is enlarged – “Magnification times 100, for starters.” Yeah okay – seriously?

Here’s the image, and the supposed enlargement. Besides the fact that the face is partially in shadow, it would be impossible to extract the image of the eye as shown due to the angle of the face.

CSI_enlargement

Consider a 3264×2448 pixel image. From that we extract a sub-image of the eye 120 × 104 (enlarged here otherwise it would be too small). Now enlarge that 100 times = 12,000 × 10,400 pixels = 124MP. The image has something in it, possibly some people, but it’s impossible to create information that wasn’t there in the first place. The image was taken at about a distance of 4-5 feet.

debunkCornea1

Garbage in – garbage out.

There are people doing work in this area, like the CAVE group from Columbia University. So it is possible to extract an image from the reflection in someones cornea, the only question remaining is how close do you have to be to acquire the image?

To determine this let’s do a couple of experiments. In the first experiment, I took an image of my right eye using my iPhone 5, with a 1.2MP “Facetime” camera. I then magnified the image two times. It is possible to see a reflection in the cornea, but the image is flipped, and there is not much detail. Processing this image further would not likely result in anything better. Note how close the image was taken as well.

debunkCornea2

The second experiment involved a 12MP digital SLR, which resulted in an image not much bigger than that from the iPhone, it part due to focusing constraints on the camera. At two times magnification, it is possible to make out certain objects in the image. So it might be possible to tell that there is a person an image, but identifying them through such an image is laughable, especially from a low-resolution security camera anywhere from 4-8 feet away.

debunkCornea3

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