What is photoplethysmography (PPG)?

Photoplethysmography is a technique that detects blood volume changes in microvascular tissue by measuring the variation in light absorption. Medical pulse oximeters use the same principle with dedicated LED/photodiode pairs. This browser tool approximates the concept using the camera's image sensor instead of a dedicated sensor.

Important limitations

Results vary significantly depending on camera quality and lighting.
Motion artifacts from hand movement cause inaccurate readings.
This tool is not a medical device and must not be used for medical purposes.

Your camera feed never leaves your device

All signal processing is performed locally using the Canvas API and JavaScript. No video frames or health data are sent to any server.

How rPPG differs from medical PPG

Medical pulse oximeters use dedicated near-infrared LED and photodiode pairs pressed against the skin to measure blood volume changes with high signal-to-noise ratio. Remote photoplethysmography (rPPG) attempts the same measurement using a standard camera and ambient reflected light from the face or fingertip. Because it relies on ambient lighting and a general-purpose image sensor rather than a controlled light source and sensor, the signal is much weaker and more susceptible to noise from movement, lighting variation, and skin tone differences. rPPG is an active research area and has shown reasonable accuracy in controlled laboratory settings, but consumer device implementations have much higher error rates.

Optimal conditions

Even, bright lighting from above or in front: overhead room lighting or a desk lamp directed at your face or finger. Avoid backlighting.
Clean camera lens: smudges or scratches reduce signal quality.
Stay very still: motion artifacts are the primary source of error. Rest your arm or hand on a stable surface and avoid breathing deeply during measurement.
Cover the camera completely with your fingertip: press firmly but not hard enough to blanch the skin, which would reduce blood flow visibility.