Adjusting Lighting, Perspective
Improved focusing is just the beginning; computational photography could also enable people to adjust the lighting of a scene, or even change the camera’s perspective, after a shot has been taken. This is the kind of trick that computer vision makes possible. “It’s difficult to do if your computer only has an understanding of the image at the level of pixels,” says Freeman. “But if you can give the computer an understanding of that image in terms of higher-level concepts, like lighting or shape, then you can let the user adjust the knobs controlling those quantities.”
This higher-level understanding comes from image analysis algorithms that let a computer “see” the components of a picture. For example, an algorithm can identify which components of the image are due to the coloring of an object’s surface and which are due to the modulation of light reflected by its shape. Once that is known, a user can adjust surface coloration and lighting effects independently. The goal is to build a system that can identify, say, where the edge of a dark piece of prime rib ends and the shadow it casts on a plate begins.
Such techniques, Raskar says, could reveal details–such as subtle facial expressions–that would previously have been obscured by shadows. In short, cameras will be able to more closely capture the essence of a scene. “When you’re walking down the street with a friend, you can be in any type of lighting and you can see how beautiful this person is,” he says. “Right now a photograph can’t do that.” But computational techniques are narrowing the gap that still separates the eye and brain from the camera. Ten years from now, he says, that may be exactly what a photograph can do.