Supported Vital Signs
VitalLens uses computer vision and signal processing to turn standard video into high fidelity physiological data.
This guide explains what we measure, how we derive it, and which models support specific metrics.
Not a Medical Device
VitalLens is NOT a medical device. The estimates provided are for general wellness and informational purposes only. They are not intended for medical diagnosis, cure, mitigation, treatment, or prevention of any disease.
The Foundation: Waveforms
At its core, the VitalLens API does not just "guess" a heart rate number. It extracts two fundamental continuous waveforms from the video feed. All other metrics are derived from these signals using industry-standard signal processing techniques.
1. PPG Waveform (Photoplethysmogram)
- What it is: A measurement of blood volume changes in the microvascular tissue of the face.
- How we get it: We detect imperceptible variations in skin color caused by the cardiac cycle (your heart pumping blood).
- Used for: Heart Rate, Heart Rate Variability (HRV).
2. Respiratory Waveform
- What it is: A measurement of the breathing cycle (inhalation and exhalation).
- How we get it: We track subtle, rhythmic motion of the upper torso and head associated with breathing mechanics.
- Used for: Respiratory Rate.
Derived Metrics
Once the waveforms are extracted, we apply peak detection, filtering, and spectral analysis to calculate global vital signs.
Cardiac Metrics
| Metric | Full Name | Description |
|---|---|---|
| Heart Rate | Pulse Rate | The speed of the heartbeat measured in beats per minute (bpm). |
| HRV (SDNN) | Standard Deviation of NN Intervals | The "gold standard" for overall HRV. Reflects total autonomic variability. |
| HRV (RMSSD) | Root Mean Square of Successive Differences | A primary measure of parasympathetic activity. |
| HRV (LF/HF) | Low Frequency / High Frequency Ratio | A frequency-domain metric often used to estimate the balance between sympathetic (stress) and parasympathetic activity. |
Respiratory Metrics
| Metric | Full Name | Description |
|---|---|---|
| Respiratory Rate | Breathing Rate | The number of breaths taken per minute (bpm). |
Model Capabilities & History
Not all models are created equal. As our research advances, we introduce new models with higher fidelity signal extraction.
VitalLens 2.0 (Current State-of-the-Art)
Our flagship model. It features a completely redesigned architecture capable of extracting PPG signals with enough fidelity to measure Heart Rate Variability (HRV), which requires millisecond-level precision.
- Supports: HR, RR, HRV (SDNN, RMSSD, LF/HF).
VitalLens 1.1 (Standard)
An evolution of our original launch model. While it benefits from a larger training dataset than v1.0 (improving Heart Rate and Respiratory Rate accuracy), the PPG signal is not clean enough for reliable HRV analysis.
- Supports: HR, RR.
VitalLens 1.0 (Legacy)
Our original launch model. It established the baseline for simultaneous PPG and Respiratory estimation.
- Status: Deprecated (Legacy support only).
- Supports: HR, RR.
Capability Matrix
| Feature | VitalLens 2.0 | VitalLens 1.1 | VitalLens 1.0 |
|---|---|---|---|
| PPG Waveform |  |
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| Respiratory Waveform | |
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| Heart Rate | |
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| Respiratory Rate | |
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| HRV (SDNN / RMSSD) | |
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| HRV (LF / HF) | |
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Data Requirements
Because physiological signals are time-dependent, the API requires a minimum duration of clean video to calculate certain metrics.
Minimum Durations
If a video is shorter than the required duration, the API will return null for that specific metric, even if the model supports it.
Why duration matters for HRV
Heart Rate Variability is a statistical measure of the irregularity between heartbeats.
- Time-Domain (SDNN, RMSSD): We need at least 20 seconds (approx 20-30 beats) to calculate a statistically significant standard deviation.
- Frequency-Domain (LF/HF): We need at least 55 seconds to capture the "Low Frequency" (0.04–0.15 Hz) waves. A 30-second video simply does not contain enough data to "see" these slow waves.
Duration Cheat Sheet
| Metric | Minimum Duration | Recommended Duration |
|---|---|---|
| Heart Rate | 5 seconds | 10+ seconds |
| Respiratory Rate | 10 seconds | 15+ seconds |
| HRV (SDNN, RMSSD) | 20 seconds | 30+ seconds |
| HRV (LF/HF) | 55 seconds | 60+ seconds |