Saturday, November 26, 2005

Light Field Camera Always In Focus

Shown: Near focus - far focus - all in focus

Anne Strehlow

Ren Ng, a computer science graduate student in the lab of Pat Hanrahan, the Canon USA Professor in the School of Engineering, Stanford University, has developed a "light field camera" capable of producing photographs in which subjects at every depth appear in finely tuned focus.

"Currently, cameras have to make decisions about the focus before taking the exposure, which engineering-wise can be very difficult," said Ng. "With the light field camera, you can take one exposure, capture a lot more information about the light and make focusing decisions after you've already taken the shot. It is more flexible."

The light field camera, sometimes referred to as a "plenoptic camera," looks and operates exactly like an ordinary handheld digital camera.
The light field camera adds an additional element—a microlens array—inserted between the main lens and the photosensor. Resembling the multi-faceted compound eye of an insect, the microlens array is a square panel composed of nearly 90,000 miniature lenses. Each lenslet separates back out the converged light rays received from the main lens before they hit the photosensor and changes the way the light information is digitally recorded. Custom processing software manipulates this "expanded light field" and traces where each ray would have landed if the camera had been focused at many different depths. The final output is a synthetic image in which the subjects have been digitally refocused.

Computer scientists create 'light field camera' banishing fuzzy photos


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