Researchers Propose Using Smartphones to Find Hidden Cameras

A team of researchers from the National University of Singapore and Yonsei University has introduced an innovative concept: using time-of-flight (ToF) sensors in modern smartphones to detect hidden cameras. ToF cameras, sometimes called “depth cameras,” work similarly to sonar but use light instead of sound. The sensor emits infrared light and measures the time it takes for the light to bounce back from an object. Essentially, the sensor consists of a diode and a special photosensitive matrix, allowing it to determine not only the distance to objects but also their shape.

ToF sensors have only recently appeared in smartphones. For example, Sony ToF laser sensors are included in the iPhone 12 and 13, as well as the Galaxy S20+, where they are used for augmented reality applications and to add depth information to 2D images.

Now, researchers suggest using these devices to search for hidden cameras. Their findings were presented at the ACM SenSys (Conference on Embedded Networked Sensor Systems).

LAPD: Laser-Assisted Photography Detection

The researchers have named this technique LAPD (Laser-Assisted Photography Detection). It is a method for detecting tiny hidden lenses by searching for unusually intense reflections in the scanned area. The experts emphasize that covert surveillance and the use of hidden cameras are becoming a global problem.

“Tiny spy cameras placed in locations such as hotel rooms, restrooms, or fitting rooms pose a significant threat to privacy worldwide. For example, in South Korea alone, more than 6,800 such cases were reported last year. Criminals can place hidden cameras anywhere, while the public remains defenseless. That’s why we’re doing this work and why we hope that detecting hidden cameras will become more common,” the researchers stated.

Of course, there are already special devices for detecting hidden cameras and other spy electronics (such as the CC308+ and K18). It’s even possible to build such a device yourself. However, the researchers argue that these gadgets are difficult to use correctly. Meanwhile, almost everyone now carries a smartphone, and a specialized app like LAPD could be an accessible, convenient, and accurate alternative.

Detection Rates and Effectiveness

According to the researchers, “Based on our comprehensive studies, LAPD demonstrates a hidden camera detection rate of 88.9%, compared to the unaided eye, which can only detect 46% of hidden cameras.”

They also note that the specialized K18 detector finds spy devices in only 62.3% of cases using the continuous method (and 57.7% using the blinking method). Moreover, LAPD boasts the lowest false positive rate (16.67%) compared to the two K18 modes (26.9% and 35.2%) and the unaided eye (54.9%).

The experts promise to release the LAPD source code as open source in the near future.