The magic of Plenoptic Camera aka “Light Field Camera”

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Let’s collectively brush up on our knowledge of the plenoptic camera, or the so-called “light-field camera.” Here’s an entry from Wikipedia on the very subject matter:

A plenoptic camera, also called a light-field camera, is a camera that uses a microlens array (also known as a lenticular lens array) to capture 4D light field information about a scene. Such light field information can be used to improve the solution of computer graphics related problems. Adelson and Wang proposed the design of a plenoptic camera that can be used to significantly reduce the correspondence problem in stereo matching. To achieve this, an array of microlenses is placed at the focal plane of the camera main lens. The image sensor is positioned slightly behind the microlenses. Using such images the displacement of image parts that are not in focus can be analyzed and depth information can be extracted.

The same camera system can be used to enable the possibility to refocus an image virtually on a computer after the picture has been taken as explained by Ng, et al. The drawback of such a system is the low resolution that the final images have. As one microlens samples the light directions at one spatial point an increase in the number of image pixels can only be done by increasing the number of microlenses by the same amount. To overcome this limitation, Lumsdaine and Georgiev describe a new design of a plenoptic camera, called focused plenoptic camera where the microlens array is positioned in front of or behind the focal plane of the main lens. This modification samples the light field in a different way that allows to have a higher spatial resolution by having a lower angular resolution the same time. With this design images can be refocused with a much higher spatial resolution.

So, does this have anything to do with Ren Ng’s light field photography? A photographer friend thinks so.

What’s funny is if you read the Wikipedia article (above) on plenoptic camera it hints [closely] at the fact that Ren Ng is one of the people in the Stanford team that used a plenoptic camera that used a 90,000 microlens array to take a 16-megapixel image that could be refocused after being taken, and describes Lytro as a “Stanford spinoff.” So, yeah. It does, in fact, sound like Lytro uses the plenoptic camera technique.

More and more information comes to light. And it’s all interesting.


Written by dominiquejames

June 22, 2011 at 7:27 PM

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