Integral imaging

Integral imaging is a three dimensional imaging technique that captures and reproduces a light field by using a two dimensional array of microlenses (or lenslets), sometimes called a fly's eye lens, normally without the aid of a larger overall objective or viewing lens. In capture mode, in which a film or detector is coupled to the microlens array, each microlens allows an image of the subject as seen from the viewpoint of that lens's location to be acquired. In reproduction mode, in which an object or source array is coupled to the microlens array, each microlens allows each observing eye to see only the area of the associated micro image containing the portion of the subject that would have been visible through that space from that eye's location. The optical geometry can perhaps be visualized more easily by substituting pinholes for the microlenses, as has actually been done for some demonstrations and special applications. A display using integral imaging is a type of light field display. The result is a visual reproduction complete with all significant depth cues, including parallax in all directions, perspective that changes with the position and distance of the observer, and, if the lenses are small enough and the images of sufficient quality, the cue of accommodation — the adjustments of eye focus required to clearly see objects at different distances. Unlike the voxels in a true volumetric display, the image points perceived through the microlens array are virtual and have only a subjective location in space, allowing a scene of infinite depth to be displayed without resorting to an auxiliary large magnifying lens or mirror. Integral imaging was partly inspired by barrier grid autostereograms and in turn partly inspired lenticular printing.

Inventor Gabriel Lippmann called the technique "photographie intégrale" (in French). It is usually translated literally as "integral photography", which suggests the integration of a whole image from parts of many small ones. However, a more usual meaning of the French word "intégrale" is "complete" or "unabridged", so that "complete photography" is another valid translation of Lippmann's perhaps deliberately ambiguous name for it.