The new digital camera filter, which is being designed specifically for smartphones, lets in three times more light than conventional filters. Traditional filters are designed to allow in only the three primary colors of the light spectrum – i.e., red, blue, and green – while absorbing the rest of the color spectrum, which means that most of the light coming in is filtered out before reaching the image sensor.
"If you think about it," says University of Utah Electrical and Computer Engineering professor Rajesh Menon, "this is a very inefficient way to get color because you’re absorbing two thirds of the light coming in. But this is how it’s been done since the 1970s. So for the last 40 years, not much has changed in this technology."
The result is the familiar dark and grainy images in photos taken under low-light conditions. According to Menon, "Low-light photography is not quite there and we are trying to fix that. This is the last frontier of mobile photography."
Using a combination of hardware and software, the new color filter lets all the light pass through to the camera sensor. The filter itself is a one-micron-thick wafer of glass that bends the light in certain ways as it passes through to create a series of color patterns or codes, which are then "decoded" by software.
This image illustrates how light passes through the new camera color filter before it reaches the digital camera sensor. Since – unlike conventional digital camera filters – all of the light reaches the camera sensor, photos taken with the new filter are much cleaner and brighter in low-light conditions.
The new filter produces at least 25 new codes, or colors, that pass through to the camera’s image sensor. According to the researchers, it produces photos that are much more accurate, and with nearly no digital grain.
"You get a lot more color information than a normal color camera. With a normal camera, you only see red, green or blue. We can do 25 or more,” says Menon. "It’s not only better under low-light conditions but it’s a more accurate representation of color."
According to Menon, the new filter can also be less expensive to manufacture as it is simpler than current filters, which require three steps to produce – one for each of the primary colors. Further, he says, the new filter will not only improve consumer smartphone cameras, but also offer significant potential in other applications, such as for robots, self-driving cars, security cameras, and drones.
"In the future, you need to think about designing cameras not just for human beings but for software, algorithms and computers. Then the technology we are developing will make a huge impact."
Menon has created a company, Lumos Imaging, to commercialize the new filter for use in smartphones. The first commercial products that use this filter could be out in three years.