Indian researchers working on imaging in foggy conditions

Researchers have demonstrated the tech by conducting experiments in foggy winter mornings.

New Delhi: Imaging of objects in foggy weather conditions may now be clearer as researchers have now found a method that can improve the images captured on such days.

The technique involves modulating the light source and demodulating them at the observer’s end.

Research by a team has offered a solution for improving the image quality without heavy computations.

The team from the Raman Research Institute (RRI), Bengaluru, an autonomous institute of the Department of Science and Technology; Space Applications Centre, Indian Space Research Organisation, Ahmedabad; Shiv Nadar University, Gautam Buddha Nagar; and Universite Rennes and Universite Paris-Saclay, CNRS, France, modulated the light source and demodulated it at the observer’s end to achieve sharper images.

The research was published in the journal ‘OSA Continuum’, said the Ministry of Science and Technology in a statement.

The researchers have demonstrated the technique by conducting extensive experiments on foggy winter mornings at Shiv Nadar University.

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. The researchers kept a camera at a distance of 150 metres from the LEDs. The camera captured the image and transmitted it to a desktop computer. Then, computer algorithms used the knowledge of the modulation frequency to extract the characteristics of the source.

“This process is called ‘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,” said the statement. The team saw a marked improvement in the image quality using the modulation-demodulation technique.

The time the computer takes to execute the process depends on the image’s size. “For a 2160 X 2160 image, the computational time is about 20 milliseconds,” shares Bapan Debnath, PhD scholar at RRI and a co-author of the study, adding that is roughly the size of the image containing the LEDs. Debanath’s colleagues had estimated the rate in 2016.

The team repeated the experiment a few times and observed the improvement each time. 

The study was partially funded by the Ministry of Science and Technology, Government of India. 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.

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