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Smartphone-based technology detects hidden cameras

Thanks to researchers in Korea, a smartphone can now be easily transformed into a hidden-camera detector.

Scientists at The Korea Advanced Institute of Science and Technology (KAIST) have developed an AI technology that can detect hidden cameras using only a smartphone and a low-cost LED device. This new security technology enables users to protect their privacy more easily and is expected to help prevent illegal filming in everyday spaces such as hotels and short-term rentals.

A KAIST research team led by Professor Jun Han of the School of Computing, in collaboration with the National University of Singapore and Singapore Management University, has developed "SweepLED," a technology that detects hidden cameras by attaching an LED case to a smartphone.

As hidden cameras are increasingly being installed in everyday spaces such as hotels, short-term rentals, and restrooms, the need is growing for detection technology that everyday users can easily operate. However, existing portable detectors require users to visually identify bright reflective spots, which can lead to false positives by mistaking reflections from metal, glass, or glossy plastic surfaces for camera lenses.

SweepLED works by keeping the smartphone camera fixed while changing only the direction of the LED illumination, then analyzing the patterns of reflected light that appear on object surfaces. Reflections from ordinary glossy objects tend to move or disappear depending on the direction of the light. In contrast, camera lenses show distinctive deformation patterns in their reflections due to their internal lens, aperture, and sensor structures.

The research team uses deep learning-based analysis to distinguish these differences in temporal reflection patterns. While conventional detection methods rely on the user's eyes to simply look for "bright spots," SweepLED is different in that it analyzes both the movement and shape changes of reflections across multiple lighting angles.

This enables more reliable detection of hidden camera lenses inside various everyday objects commonly found in lodging spaces such as chargers, clocks, remote controls, and everyday objects.

The research team evaluated SweepLED on 30 objects that may be found in real-world environments and found that it achieved approximately 94% detection accuracy. It also took less than 5 seconds to inspect a single object.

In addition, the core components of the LED case attached to the smartphone cost less than USD $7, demonstrating the potential for this technology to be developed into an affordable detection tool that general users can easily access.

"Hidden cameras pose a serious threat to personal safety and privacy in everyday spaces," said Professor Jun Han. "This research is meaningful in that it combines low-cost smartphone-based hardware with AI analysis to present the possibility of a practical detection technology that even non-experts can use."

The paper, "Hide-and-Sweep: Detecting Concealed Cameras via LED Illumination Sweeps," with KAIST doctoral student Jonghyuk Yun as first author, was presented on June 20 at ACM MobiSys 2026, one of the leading international conferences in the field of mobile computing.

Source: The Korea Advanced Institute of Science and Technology (KAIST)

Published September 2026

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