plenoptic
Of or relating to all the light, travelling in every direction, in a given space.
plenoptic: capturing light from every angle at once
A plenoptic camera or sensor captures the complete light field in a scene, meaning it records not just the intensity and color of light at each pixel, but also the direction from which that light arrives. This differs from a conventional camera, which integrates all light rays hitting a given point on the sensor into a single value. The name comes from the Greek plenum (full) and optic (light).
The term originates in the work of physicist Donald Gershun in the 1930s, who used it to describe a comprehensive description of light in three-dimensional space. In practical imaging, a plenoptic camera uses an array of tiny lenses (a microlens array) positioned above the image sensor. Each microlens focuses light onto a small region of pixels below it, effectively capturing angular information about the incoming light rays.
The primary applications lie in computational imaging and post-processing flexibility. Because directional data is recorded, a plenoptic image allows refocusing after capture, shifting the focus plane without taking another photograph. It also enables perspective shift, depth estimation, and 3D reconstruction from a single exposure. Professional and research-grade plenoptic cameras exist, though they remain expensive and require substantial computational resources to process the raw data.
The trade-off is spatial and angular resolution. The microlens array divides the sensor into regions, reducing the effective pixel count for spatial detail. A sensor with 100 million raw pixels might yield only 10 to 20 million directional samples. Processing raw plenoptic data also demands significant computing power, and the resulting files are large. These constraints keep plenoptic imaging confined to specialized domains: scientific metrology, volumetric display research, and advanced computer vision.
Related terms include light field, which is synonymous in most contexts, and integral imaging, an older technique that achieves similar results through different optical arrangements. The plenoptic approach sits at the intersection of optics engineering and computational photography, requiring expertise in both hardware design and software post-processing.