Imaging objects through fog may now be more clear; to help defence, aviation, maritime sectors

Vijay Mohan
Tribune News Service
Chandigarh, June 15

In a breakthrough that could be of immense importance to the defence, maritime and aviation sectors, researchers have found a method that can improve the clarity of images captured in foggy weather conditions.

The technique involves modulating the light sources and demodulating them at the observer’s end without heavy computations.

The researchers have demonstrated the technique by conducting extensive experiments on foggy winter mornings.

They chose ten red LED lights as the source of light.

Then, they modulated this source of light by varying the current flowing through the LEDs at a rate of about 15 cycles per second. A camera was kept at a distance of 150 meters from the LEDs, which captured the image and transmitted it to a desktop computer.

Computer algorithms then used the knowledge of the modulation frequency to extract the characteristics of the source, a process known as demodulation.

The demodulation of the image had to be done at a rate that was equal to the rate of modulation of the source of light to get a clear image.

The team saw a marked improvement in the image quality using the modulation-demodulation technique.

The experiments were repeated several times under different weather conditions and experimental setups.

The method can improve the landing techniques of aeroplanes by providing the pilot with a good view of beacons on the runway, significantly better than relying only on reflected radio waves as is presently the case.

The technique can help reveal obstacles in the path that would otherwise be hidden by fog in rail, sea, and road transportation and would also help to spot lighthouse beacons.

“The cost of the technique is low, requiring only a few LEDs and an ordinary desktop computer, which can execute the technique within a second,” according to a statement issued by the Ministry of Science and Technology on Tuesday.

“Further research can demonstrate the effectiveness in such real-life conditions. The team is investigating whether the technique can apply to moving sources,” the statement added.

The team included members from the Raman Research Institute of the Department of Science and Technology, Space Applications Centre of Indian Space Research Organisation, Shiv Nadar University and Université Rennes and Université Paris-Saclay, France.

The research has been published in the latest issue of OSA Continuum, a US-based peer-reviewed journal.

Scientists have long attempted to use the physics of scattering of light and computer algorithms to process the resulting data and improve the quality of images.

Computer algorithms, however, require processing large volumes of data, involving ample storage and significant processing time.