Light-field Camera - Technology

Technology

The first light field camera was proposed by Gabriel Lippmann in 1908, which used integral photography as the underlying technology. In 1992, 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. Potentially, this camera system can be used 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 before or behind the focal plane of the main lens. This modification samples the light field in a different way that allows for a higher spatial resolution by having a lower angular resolution at the same time. With this design images can be refocused with a much higher spatial resolution. However, the low angular resolution can introduce some unwanted aliasing artifacts. A different design using low cost printed film (mask) instead of microlens array was proposed by researchers at MERL in 2007. This design overcomes several limitations of microlens array in terms of chromatic aberrations, loss of boundary pixels, and allows higher spatial resolution photos to be captured. However, a mask based design reduces light compared to microlens arrays.