Face Verification — On‑Device FaceNet Embeddings #

Face verification for Flutter: detect a face in an image, generate an on-device embedding with a bundled TFLite model, store embeddings locally, and verify new images against the stored records using cosine similarity.

Features #

• On-device face registration and verification
• Bundled face embedding model (TFLite) — works offline
• Simple high-level API (init, register, verify, list, delete)
• Robust preprocessing and cosine-similarity matching
• Local persistence using sqflite

Installation #

Add the dependency in your app’s pubspec.yaml:

dependencies:
  face_verification: ^0.0.1

Then run:

flutter pub get

The model asset is bundled with this plugin; no extra asset setup is required for default usage.

Requirements #

iOS #

• Minimum iOS Deployment Target: 15.5
• Xcode 15.3.0 or newer
• Swift 5
• 64-bit architectures only (x86_64, arm64). Exclude 32-bit (i386, armv7).

Exclude armv7 in Xcode:

• Project > Runner > Build Settings > Excluded Architectures > Any SDK > add armv7

Update your ios/Podfile to set the deployment target and exclude 32-bit:

platform :ios, '15.5'

$iOSVersion = '15.5'

post_install do |installer|
  installer.pods_project.build_configurations.each do |config|
    config.build_settings["EXCLUDED_ARCHS[sdk=*"] = "armv7"
    config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = $iOSVersion
  end

  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)

    target.build_configurations.each do |config|
      if Gem::Version.new($iOSVersion) > Gem::Version.new(config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'])
        config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = $iOSVersion
      end
    end
  end
end

Note: You may set a newer deployment target, but not older than 15.5.

Android #

• minSdkVersion: 21
• targetSdkVersion: 35
• compileSdkVersion: 35

Ensure your Android project build.gradle/build.gradle.kts matches these values.

Additional mobile runtime notes #

• Build and install on a physical device for best results.
• iOS Simulator may not support certain ML runtimes reliably; prefer a physical device.
• Android devices should be on recent API levels. If you encounter native library load issues, test on a device with API level ≥ 26.
• Creating an iOS release archive (IPA) can strip symbols and cause a "Failed to lookup symbol" error. In Xcode:
  • Target Runner > Build Settings > Strip Style → set to "Non-Global Symbols".

Quick start #

import 'package:face_verification/face_verification.dart';

Future<void> run() async {
  // Initialize once (bundled model is used by default)
  await FaceVerification.instance.init();

  // Register a face
  final id = await FaceVerification.instance.registerFromImagePath(
    id: 'user_123',
    imagePath: '/path/to/face.jpg',
    imageId: 'img_001',
  );
  print('Registered: $id');

  // Verify a new image
  final matchId = await FaceVerification.instance.verifyFromImagePath(
    imagePath: '/path/to/another_face.jpg',
    threshold: 0.70, // adjust as needed
  );
  print('Best match: $matchId');

  // Optional: restrict matching to a known ID using staffId
  // - If staffId is provided, verification compares only with that user's record
  // - If staffId is null, verification compares against all registered faces
  final matchSpecific = await FaceVerification.instance.verifyFromImagePath(
    imagePath: '/path/to/another_face.jpg',
    threshold: 0.70,
    staffId: 'user_123',
  );
  print('Match for user_123: $matchSpecific');

  // Optional: List all registered faces
  final records = await FaceVerification.instance.listRegisteredAsync();
  print('Registered count: ${records.length}');

  // Optional: delete a record
  await FaceVerification.instance.deleteRecord('user_123');

  // Optional: Dispose when done
  await FaceVerification.instance.dispose();
}

Using a custom model (optional) #

If you want to provide your own compatible embedding model, pass its asset path on init:

await FaceVerification.instance.init(
  modelAsset: 'assets/models/your_model.tflite',
  numThreads: 4,
);

Make sure the custom model path is included under your app’s flutter/assets.

Example app #

See the example in example/ for a minimal working setup and UI. Run it with:

cd example
flutter run

Troubleshooting #

• No face detected / Multiple faces detected

  • Ensure the input image has a clear, front-facing face. The API throws when zero or multiple faces are found during registration.

• Model not found

  • If you override modelAsset, ensure it is correctly listed under your app’s assets and the path is correct.

• iOS build fails for armv7

  • Confirm armv7 is excluded as described in Requirements.

• Matching quality

  • Tune threshold (default 0.70). Higher threshold = stricter match.

Reporting issues #

Please open an issue in this repository with the following details:

• Platform and versions (iOS/Android, OS, Flutter, plugin version)
• Device model and architecture
• Steps to reproduce and minimal code snippet
• Relevant logs and, if possible, a test image (redact personal data)

Contributing #

Contributions are welcome. For non-trivial changes, consider opening an issue first to discuss the approach. Please include tests or example changes when appropriate.

License #

This project is licensed under the MIT License. See LICENSE for details.

Changelog #

See CHANGELOG.md for release notes.