Super-resolution technology for smartphones

Kogakuin University has developed a super-resolution technology capable of playing video on a smartphone in real time.

It is a result of a joint research conducted by Seiichi Gohshi (professor of the Department of Information Design, the Faculty of Informatics, Kogakuin University) and Fujitsu Ltd. The new technology was employed for the “Xevic” image processing engine of Fujitsu’s arrows NX F-02H smartphone.

Unlike commonly-used “reconstructed super resolution” and “learning super resolution,” the super-resolution technology being researched by Gohshi uses an original method called “nonlinear signal processing method.”

“A nonlinear function is applied to the edges detected by applying a high-pass filter to input images,” he said. “Then, the data is compressed and added to the original images.”

Though it is similar to a conventional enhancer function, it is different in that a nonlinear function is used to supplement high-frequency components, Gohshi said. As a result, it becomes possible to reproduce images with high-resolution components that surpass the “Nyquist frequency (half of a sampling frequency),” which is the theoretical limit of super-resolution.

Also, the new method does not need repeated calculation, which is required for general super-resolution technologies, and uses a simple algorithm. So, it is suited for real-time processing.

The research on the super-resolution based on the nonlinear signal processing method started in 2012 in cooperation with Keisoku Giken Co Ltd. And the technology has already been commercialized as “FE super-resolution unit,” a commercial-use device that expands high-vision video data to 4k video data.

This time, the university further simplified the algorithm, and Fujitsu made improvements to task division and time control. As a result, real-time operation was realized by using smartphone software without dedicated hardware. The new technology can play 4k video data with a frame rate of 30fps without increasing the power consumption of a smartphone. The university also confirmed that it is possible to increase the frame rate to 60fps.

The university started the joint research in March 2015 when it received a proposal from Fujitsu.

“We receive many inquiries about the technology from overseas organizations,” the university said. “But there are problems related to intellectual property management in some cases, and we hope that it will be used for improving the technological strength of Japanese companies. So, we are dealing with joint researches and developments only with Japanese companies.”

The technology is also expected to be used for medical equipment and monitoring cameras.

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