SCPPG - Smartphone Camera Photoplethysmography #

A Flutter package for smartphone camera photoplethysmography (SCPPG) that enables heart rate monitoring using smartphone cameras.

Features #

• Simple Camera Integration: Easy-to-use controller for camera initialization and management
• Permission Handling: Built-in camera permission request management
• RGB Extraction: Real-time RGB signal extraction from camera frames
• Finger Detection: Automatic detection of finger presence on the camera
• Customizable Settings: Adjustable parameters for flash control, frame rate and detection thresholds
• Real-time Monitoring: Stream of camera data with timestamps for real-time analysis

Getting started #

Prerequisites #

• Flutter SDK 3.7.2 or higher
• Camera access on target devices
• Add required permissions to your app:

For Android:

Add these lines to your android/app/src/main/AndroidManifest.xml:

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

For iOS:

Add these keys to your ios/Runner/Info.plist:

<key>NSCameraUsageDescription</key>
<string>This app needs camera access to measure heart rate</string>

Installation #

Add the package to your pubspec.yaml:

dependencies:
  scppg: ^1.0.0

Usage #

Basic Implementation #

import 'package:flutter/material.dart';
import 'package:scppg/scppg.dart';

class HeartRateMonitorScreen extends StatefulWidget {
  @override
  _HeartRateMonitorScreenState createState() => _HeartRateMonitorScreenState();
}

class _HeartRateMonitorScreenState extends State<HeartRateMonitorScreen> {
  late ScppgController _controller;
  List<SCPPGData> _dataPoints = [];

  @override
  void initState() {
    super.initState();
    _controller = ScppgController(fps: 30);
    _controller.init();
    
    // Listen to SCPPG data updates
    _controller.addListener(() {
      if (_controller.ppgData != null) {
        setState(() {
          _dataPoints.add(_controller.ppgData!);
          // Process data or calculate heart rate here
        });
      }
    });
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Heart Rate Monitor')),
      body: Column(
        children: [
          // Camera preview
          if (_controller.isSensing)
            SizedBox(
              height: 300,
              child: CameraPreview(_controller.cameraController),
            ),
          
          // Controls
          ElevatedButton(
            onPressed: () {
              if (_controller.isSensing) {
                _controller.stopSensing();
              } else {
                _controller.startSensing();
              }
              setState(() {});
            },
            child: Text(_controller.isSensing ? 'Stop' : 'Start'),
          ),
          
          // Toggle flash
          ElevatedButton(
            onPressed: () {
              _controller.isFlashOn = !_controller.isFlashOn;
            },
            child: Text('Toggle Flash'),
          ),
          
          // Display readings (red channel)
          if (_dataPoints.isNotEmpty)
            Text('Latest R value: ${_dataPoints.last.r?.toStringAsFixed(2)}'),
        ],
      ),
    );
  }
}

Advanced Usage #

For more advanced usage, including implementing heart rate algorithms, charts, and signal processing, check out the examples in the /example folder.

API Reference #

ScppgController #

The main controller class for the SCPPG functionality.

// Create a controller
final controller = ScppgController(fps: 30);

// Initialize (requests permissions)
await controller.init();

// Start/stop sensing
await controller.startSensing();
controller.stopSensing();

// Control flash and exposure
controller.isFlashOn = true;
controller.isFocusAndExposureLocked = true;

// Adjust finger detection sensitivity
controller.redRatioThreshold = 30; // 0-100

SCPPGData #

A data class representing the RGB values extracted from a camera frame.

// Access data
SCPPGData data = controller.ppgData;
double? redValue = data?.r;
double? greenValue = data?.g;
double? blueValue = data?.b;
DateTime? timestamp = data?.timestamp;

Photoplethysmography Theory #

Photoplethysmography (PPG) is an optical technique for detecting blood volume changes in microvascular tissue. When light from the phone's flash passes through the fingertip, the amount of light absorbed varies with each heartbeat. This package extracts the changes in red, green, and blue color channels, with the green channel typically providing the clearest signal for heart rate monitoring.

Additional information #

For more information on using SCPPG for heart rate monitoring, see:

• Check out the full example app in the /example folder
• Photoplethysmography Principles

Issues and Feedback #

Please file issues, bugs, or feature requests in our issue tracker.

License #

This project is licensed under the MIT License - see the LICENSE file for details.