This $7 Smartphone Accessory Can Spot Hidden Cameras in Seconds

Researchers have developed a $7 smartphone accessory that can detect hidden cameras within five seconds with 94% accuracy.

“SweepLED”, an LED case that clips to any smartphone and spots illegal filming by covert cameras in everyday spaces, was developed by a team of scientists at Korea Advanced Institute of Science and Technology (KAIST).

Hidden cameras can be placed in a range of everyday spaces, including hotels, short-term rentals, and restrooms, creating a need for detection tools that members of the public can use. Existing portable detectors, however, often rely on users identifying bright reflections, which can make it difficult to distinguish a camera lens from an ordinary reflective surface. Reflections from materials such as metal, glass, or glossy plastic can, for example, be mistaken for a camera lens, resulting in false positives.

According to a news release, SweepLED takes a different approach by looking at how those reflections behave. The system keeps the smartphone camera fixed while changing only the direction of the LED light, then analyzes the reflections that appear on nearby surfaces. Reflections from ordinary glossy materials tend to move or disappear as the direction of the light changes. Camera lenses, on the other hand, produce distinctive changes in the shape of their reflections because of the lens, aperture, and sensor structures inside them.

Overview of SweepLED. The system scans objects using a smartphone case equipped with an LED array and detects hidden cameras by analyzing the distinctive reflection patterns of camera lenses under changing illumination. | Credit: KAIST

The research team used deep learning to analyze these changes over time and distinguish between the two. Instead of simply asking users to look for “bright spots,” SweepLED examines both the movement of reflections and changes in their shape as the light is directed at an object from different angles.

In short, SweepLED uses a smartphone’s camera and LED light, combined with deep-learning analysis, to identify the telltale reflection patterns of hidden camera lenses. The approach could provide a more reliable way to identify hidden camera lenses concealed inside everyday objects commonly found in lodging spaces, including chargers, clocks, remote controls, and other household items.

According to Digital Trends, SweepLED captures the entire light sweep as a short video, which is then analyzed by an AI model trained to recognize the distinctive deformations produced by camera lenses. The system can then identify where a hidden camera may be located. In tests involving 30 everyday objects that could realistically be found in a hotel room or rental property, SweepLED detected hidden cameras with about 94% accuracy, taking less than five seconds to scan each object.

As Digital Trends notes, a recent UCL study found that people using consumer-grade hidden camera detectors missed 59% of the devices during testing. Against that backdrop, SweepLED’s 94% accuracy in laboratory testing is a promising result, although further testing in real-world settings will be needed to see how well it performs outside the lab.

The full study can be read here.

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