In a webinar sponsored by the Society of Motion Picture & Television Engineers, V. Michael Bove, Jr., from MIT's Media Lab, said holographic imaging might actually appear on handheld devices or even on desktops in the "relatively near future."
"Holo(graphic) video could be the solution to providing good TV, if we implement it correctly to coexist with other 3D (technologies)," Bove said. "It is more practical than (you) think." Living room applications will take longer, and theatrical displays will require breakthroughs because of the amount of computation required and the pixel logistics.
So what is a hologram? The technical answer is a medium that uses diffraction of light to reconstruct light wavefronts identical or close to those that come from a real object, Bove said. In (slightly) more laymen's terms, he said to think of a special window that can remember the diffraction pattern of the light wavefronts that have passed through in order to reconstruct them later. A viewer can no longer distinguish whether the scene is still present on the other side of the window or if it is a recreation.
"It is like looking at the scene," Bove said. "There is nothing to indicate it is not there. With the best holograms, you are not able to tell it is not a (real or current) scene."
Oftentimes when things are labeled as holograms today, they actually are not. For example, when images of performers or politicians are projected, it is most likely an illusion akin to an old stage trick that uses a half-silvered mirror. "Digital projectors (are used) to create the appearance that someone is on stage, but you are looking at a 2D image in a half-silvered mirror," Bove said.
Even "real" holographic images, like one of Bob Marley at the MIT Museum, are static. Why? The answer is simply physics. A moving holographic image of acceptable quality requires three orders of magnitude more pixels than a 2D image of the same size; the ability to change these pixels many times per second; a high resolution image sensor to receive the image; and a way to transmit from the source to the destination, Bove said.
Research is being done at MIT and other institutions around the country to address the challenges. For example, Bove's group is working on capturing the scene in a different way using different types of cameras or arrays of cameras, and then computing the hologram at the display. The hologram could be subdivided into small pieces called "hogels," or holographic pixels, each of which would be converged back into a physically correct hologram, real-time, on a GPU. This is really fast, but leads to all directions having the same wavefront curvature, and therefore one of the visual cues is incorrect, Bove said.
"We have developed a new algorithm for calculating holographic stereograms - Diffraction Specific Coherent Panoramagram," Bove said. "It can compute in real time and is a very useful process."