"Arriving at each pixel, the light's coming at a certain angle, and that contains important information," explains Crozier. "Cameras have been developed with all kinds of new hardware—microlens arrays and absorbing masks—that can record the direction of the light, and that allows you to do some very interesting things, such as take a picture and focus it later, or change the perspective view. That's great, but the question we asked was, can we get some of that functionality with a regular camera, without adding any extra hardware?"

There are lytro cameras which can be focused afterwards.


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Isn't this just what lytro does though? It detects the direction of the light so it can focus later.

"Arriving at each pixel, the light's coming at a certain angle, and that contains important information," explains Crozier. "Cameras have been developed with all kinds of new hardware—microlens arrays and absorbing masks—that can record the direction of the light, and that allows you to do some very interesting things, such as take a picture and focus it later, or change the perspective view. That's great, but the question we asked was, can we get some of that functionality with a regular camera, without adding any extra hardware?"

The key, they found, is to infer the angle of the light at each pixel, rather than directly measuring it (which standard image sensors and film would not be able to do). The team's solution is to take two images from the same camera position but focused at different depths. The slight differences between these two images provide enough information for a computer to mathematically create a brand-new image as if the camera had been moved to one side.