sives. There would no longer be a need
for long security queues.
Scientists are peering into other concepts that are equally mind-bending.
For example, MIT associate professor Ramesh Raskar and a group of researchers are exploring the emerging
field of Femto-photography; their goal
is to build a camera that can see around
corners and peer beyond the line of
sight. Such a device could provide access to dangerous and inaccessible locations including mines, contaminated
sites, and inside certain machinery. He
describes the method as using “echoes
of light” to capture information about
the overall environment.
The concept, which the group has
already tested successfully, uses a laser
light burst directed at a wall or object.
The camera records images every 2 picoseconds, the time it takes light to travel
0.6 millimeters. By measuring the time
it takes for scattered photons to reach a
camera—and repeating the process over
50 femtoseconds ( 50 quadrillionths of a
second), it is possible to construct a view
of the hidden scene. The system relies
on a sophisticated algorithm to decode
photon patterns. At present, the entire
process takes several minutes, though
researchers hope to reduce the imaging
time to less than 10 seconds.
Baraniuk believes researchers will
overcome many existing hurdles—par-
ticularly surrounding signal process-
ing and computational analysis—over
the next decade. They have already
taken a giant step in that direction by
constructing algorithms that sidestep
conventional signal processing and in-
stead mine big data. Over the next few
years, as imaging systems and comput-
ers advance, once-abstract and seem-
ingly unachievable photographic meth-
ods will become reality. One company,
InView, has already begun to introduce
cameras that use advanced imaging
and compressive sensing techniques.
Werner says computational imagery
increasingly will tie in augmented reality. He believes computational imaging and sensing will also meld with 3D
cameras, night vision, adaptive resolution technology, holographic displays,
and negative index material refraction.
As hardware gets “faster and cheaper
and algorithms become more sophisticated,” next-generation cameras and
image-capture devices will also connect with social networks and provide
new ways for people to view and share
the surrounding environment.
“We are on the verge of remarkable
breakthroughs in the way we think
about photography and use computational optics,” Baraniuk concludes.
In fact, “At some point, the end result
might not be an actual image. The
camera might make inferences and
decisions based on certain parameters, including where a person is located in a room or the overall pattern
of cars on a network of roads. We are
moving into a world where there will
be lots of different ways to sense what
is taking place around us.”
Huang, G., Jiang, H., Matthews, K., Wilford, P.
Lensless Imaging by Compressive Sensing,
IEEE International Conference on Image
Processing, ICIP 2013, Paper #2393, May
Katz, O., Bromberg, Y., Silberberg, Y.
Compressive Ghost Imaging, Dept.
of Physics of Complex Systems, The
Weizmann Institute of Science, Rehovot,
More is Less: Signal Processing and the
Data Deluge, Science, Data Collections
Booklet, 2011. http://www.ncbi.nlm.nih.gov/
Velten, A., Willwacher, T., Gupta, O.,
Veeraraghavan, A., Bawendi, M.G., Raskar, R.
Recovering three-dimensional shape around
a corner using ultrafast time-of-flight
imaging, nature Communications 3, Article
number: 745, Published 20 March 2012.
Samuel Greengard is an author and journalist based in
west linn, or.
© 2013 aCm 0001-0782/13/12 $15.00
single sensor; each mirror corresponds
to a particular pixel. Just as high-resolution photographic images can be
compressed by stripping out unneeded
data and storing the file in JPEG format, it is possible to extrapolate on existing data in the image. The technique
cycles through 50,000 measurements
in order to find the optimal directional
orientation for the mirrors.
The concept is appealing because
a single-pixel design reduces the required size, complexity, and cost of a
photon detector array down to a single
unit. It also makes it possible to use
exotic detectors that would not work
in conventional digital cameras. For
example, it could include a photomultiplier tube or an avalanche photodi-ode for low-light imaging, layers of
photodiodes sensitive to different light
wavelengths for multimodal sensing,
or a spectrometer for hyperspectral
imaging. In addition, a single-pixel design collects considerably more light in
each measurement than a pixel array,
which significantly reduces distortion
from sensor nonidealities like dark
noise and read-out noise.
These multiplexing capabilities,
combined with shutterless sensing
and compressive sensing, could lead to
new types of cameras that might, for example, allow motorists to see through
fog or to better see objects on the road
at night, and thus avoid crashing into
them or driving over them. Ultimately,
the concept redraws the boundaries of
imaging. “What we have come to realize,” Baraniuk says, “is that digital measurements that we generate at a scene
or in the world around us do not need
to be exactly analogous with how we use
a film or conventional digital camera.”
There also is growing interest in
engineering cameras that can see
through solid objects. Researchers at
Duke University, for example, have
developed a camera that detects and
records microwave signals. The device uses a one-dimensional aperture
constructed from copper-based meta-material to capture data that it sends
to a computer, which constructs an
actual image. Among other things, the
device could prove valuable to law enforcement agencies; for example, passengers at airports could simply walk
past the device at a security checkpoint
while it scans for weapons and explo-
“We are on the
verge of remarkable
breakthroughs in the
way we think about
photography and use