Now, Pat Hanrahan and his team at Stanford University have figured out how to adjust the light rays after they have reached the camera. They inserted a sheet of 90,000 lenses, each just 125 micrometres across, between the camera's main lens and the image sensor. The angle of the light rays that strike each microlens is recorded, as well as the amount of light arriving along each ray. Software can then be used to adjust these values for each microlens to reconstruct what the image would have looked like if it had been properly focused. That also means any part of the image can be refocused - not just the main subject.The researchers' page on the "light field camera" includes papers and a gallery of refocusable images, and videos of focussing through a frozen moment. The examples look uncanny, as if splashes of water frozen in space were unbelievably intricate dioramas.
Applications of this technology include surveillance (where being able to change focus after the fact would often be useful) and motion photography; I imagine we may see this in films, music videos and ads soon enough as well.