In this
illustration, light passes through the new camera color filter developed by
University of Utah
Electrical and Computer Engineering professor Rajesh Menon
before it reaches
the digital camera sensor. Since all of the light reaches the sensor,
unlike
conventional digital camera filters where only a third of the light passes
through,
photos taken with
Menon's new filter are much cleaner and brighter in lowlight.
(October 29, 2015) UTAH
ENGINEERS DEVELOP CAMERA FILTER THAT PRODUCES SHARPER, BRIGHTER PHOTOS IN LOW
LIGHT.
Anyone who’s taken a picture of birthday candles being blown
out or a selfie during a romantic candlelit dinner knows how disappointing it
is when the photo comes out dark and grainy.
But University of Utah Electrical and Computer Engineering
professor Rajesh Menon has developed a new camera color filter that lets in
three times more light than conventional filters, resulting in much cleaner,
more accurate pictures taken in lowlight. The new filter can be used for any
kind of digital camera, but Menon is developing it specifically for smartphone
cameras. Menon and doctoral student Peng Wang describe the invention today in
the journal, Optica.
“Overall, camera phones are very good, but they are not very
good in lowlight,” says Menon. “If you go out on a hike in the evening and take
a picture of the sky you will see that it’s very grainy. Lowlight photography
is not quite there and we are trying to fix that. This is the last frontier of
mobile photography.”
Traditional digital cameras, whether they are
point-and-shoot cameras or the now-ubiquitous smartphone cameras, use an
electronic sensor that collects the light to make the picture. Over that sensor
is a filter designed to allow in the three primary colors: red, blue and green.
But by doing so, natural light hits the filter, and the filter absorbs two
thirds of the color spectrum in order to let through each of the three primary
colors.
University of Utah
Electrical and Computer Engineering professor Rajesh Menon has
developed a new
camera color filter for digital cameras that lets in three times more light
than conventional
filters, resulting in much cleaner, more accurate pictures taken in lowlight.
The new filter can
be used for any kind of digital camera, but Menon is developing it
specifically for
smartphone cameras.
“If you think about it, this is a very inefficient way to get
color because you’re absorbing two thirds of the light coming in,” Menon says.
“But this is how it’s been done since the 1970s. So for the last 40 years, not
much has changed in this technology.”
Menon’s solution is to use a color filter that lets all light
pass through to the camera sensor. He does this with a combination of software
and hardware.
Menon has designed a new color filter that is about a micron
thick (100 times thinner than a human hair). It is a wafer of glass that has
precisely-designed microscopic ridges etched on one side that bends the light
in certain ways as it passes through and creates a series of color patterns or
codes. Software then reads the codes to determine what colors they are.