No smartwatch, no ring, no chest strap. A guided camera scan reads your pulse from the phone you already own -- here is how it works, how to get a clean reading, and where the limits are.
Every heartbeat pushes blood through the capillaries just under your skin, changing how much light it absorbs. A camera recording at normal frame rates captures that shift as a faint rhythmic signal -- remote photoplethysmography, the same optical principle a clip-on pulse oximeter uses, without contact.
Sit still and breathe normally (standing alone can add 10-20 bpm). Use decent, steady light. Hold the phone steady -- motion is the biggest source of noise. Measure at the same time of day, ideally morning before coffee, for a comparable trend.
Athletic: 40-54 bpm. Typical: 55-75 bpm, where most healthy resting adults land. Higher: 76-90 bpm, often stress, poor sleep, heat, caffeine or alcohol. Persistently above 90 bpm at rest on quiet days is worth a conversation with a doctor. These are population bands for orientation, not a diagnosis.
Not continuous monitoring -- it's a snapshot of a calm moment, which is what a wearable does better. Not for movement -- motion swamps the optical signal, so a chest strap remains right for training zones. No blood oxygen -- SpO2 needs infrared light a phone camera doesn't emit.
No. A chest strap reads electrical activity directly and stays accurate during movement. A camera reads an optical signal and needs you to sit still in reasonable light. For a calm resting measurement the two are close; during exercise a strap is the better tool.
Quantum Khor is a wellness companion, not a medical device. It does not diagnose, treat or prevent any condition.