Cameras use defocus blur tool to see through objects

Researchers at Stanford University's Computer Graphics Laboratory have developed a technique to allow a camera system to "see through" objects partially blocking a target.

It involves processing images gathered by up to 100 cameras and combining the information to simulate the effect of having a gigantic lens with a large aperture - a big hole through which the light rays come through.

By doing this they were able to vary which part of the image was in focus to make their target sharp and clearly visible, but would leave other objects in front of the point of interest so blurred they appeared transparent.

Details of the experiments, external - which included looking through foliage and a crowd - were collected together in a thesis published by Vaibhav Vaish in 2007.

He said the technique presented a "potentially powerful tool for surveillance".

The cost and size of the equipment may have limited its uses in the real world, but others are now trying to create a budget version of the effect using only a single camera.

Video courtesy of Marc Levoy, Stanford University.