Privacy-Conscious Surveillance Camera Turns You Into a Stick Figure

A skeletal representation of a humanoid figure is shown superimposed on a blurred background of an office or lab environment. The background includes office chairs, desks, and computer screens. The skeletal figure is made up of white lines depicting basic body structure.
Brenda Ahearn/University of Michigan.

A strange new surveillance camera aims to stop companies from collecting identifiable photos and videos of people by turning them into stick figures.

Called PrivacyLens, it was developed by a group of University of Michigan engineers who combined a standard video camera and a heat-sensing camera to more accurately detect people and turn them into child-like drawings of people.

The heat-sensing camera spots people from their body temperature and then the person’s image is replaced by a stick figure. The figure’s movements mirror those of the person it’s recording.

Close-up of an electronic device with a visible circuit board, cables, and a camera lens labeled "CCTV LENS 8MM 1:12." The device is connected with wires and components, likely part of a surveillance or security system. The background is blurred.
The round lens captures standard digital video while the square lens senses heat. The heat sensor improves the camera’s ability to spot and remove people from videos. | Brenda Ahearn/University of Michigan.
A colorful stick figure overlay is shown superimposed on the image, standing in an office space with empty desks, chairs, and office equipment in the background. The figure has distinct straight lines representing limbs, a torso, and a head outline.
Brenda Ahearn/University of Michigan.

Cameras have become ubiquitous; and not just outside the home. There is a myriad of house gadgets that have cameras including smart speakers, baby monitors, and laptop webcams.

In 2022, an iRobot Roomba robot vacuum took intimate photos of a woman sitting on the toilet and they were somehow uploaded to Facebook. The anonymity provided by PrivacyLens could prevent these things from happening.

A person is holding a handmade electronic device with a camera module attached to a circuit board. Various wires are connected to the board, and the person's hand is adjusting a component on the device. They are wearing a wristband and a short-sleeved shirt.
Brenda Ahearn/Michigan Engineering

“Most consumers do not think about what happens to the data collected by their favorite smart home devices. In most cases, raw audio, images, and videos are being streamed off these devices to the manufacturers’ cloud-based servers, regardless of whether or not the data is actually needed for the end application,” says Alanson Sample, a University of Michigan associate professor of computer science and engineering and the co-author of the study.

“A smart device that removes personally identifiable information before sensitive data is sent to private servers will be a far safer product than what we currently have.”

The raw photos from PrivacyLens are not stored on the device or in the cloud which removes the risk of a data leak. The engineers hope that this level of privacy protection will encourage more people to use cameras inside their homes for health monitoring and other needs.

“Cameras provide rich information to monitor health,” says Yasha Iravantchi, a doctoral student in computer science and engineering.

“It could help track exercise habits and other activities of daily living, or call for help when an elderly person falls.

“But this presents an ethical dilemma for people who would benefit from this technology. Without privacy mitigations, we present a situation where they must weigh giving up their privacy in exchange for good chronic care. This device could allow us to get valuable medical data while preserving patient privacy.”

Discussion