Source: https://docs.expo.dev/versions/v52.0.0/sdk/facedetector

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Expo FaceDetector

GitHub Changelog npm

A library that uses Google Mobile Vision to detect faces on images.

GitHub Changelog npm

Android (device only)

iOS (device only)

Bundled version:

~13.0.2

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Deprecated: This library is not available from SDK 51. We recommend react-native-vision-camera if you require this functionality.

expo-face-detector lets you use the power of the Google's ML Kit framework to detect faces on images.

Known issues 

Android

Face detector does not recognize faces that aren't aligned with the interface (top of the interface matches top of the head).

Installation

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This module is not available in the Expo Go app because it has dependencies that break builds for iOS Simulators.

You can create a development build to work with this package.

Terminal

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- npx expo install expo-face-detector

If you are installing this in an existing React Native app , make sure to install expo in your project.

Usage

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Settings

To configure detector's behavior modules pass a DetectionOptions object which is then interpreted by this module.

Example

You can use the following snippet to detect faces in a fast mode without detecting landmarks or whether a face is smiling.

Quick face detection

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Open in Snack

import { Camera } from 'expo-camera'; import * as FaceDetector from 'expo-face-detector'; const App = () => ( <Camera // other props onFacesDetected={handleFacesDetected} faceDetectorSettings={{ mode: FaceDetector.FaceDetectorMode.fast, detectLandmarks: FaceDetector.FaceDetectorLandmarks.none, runClassifications: FaceDetector.FaceDetectorClassifications.none, minDetectionInterval: 100, tracking: true, }} /> ); const handleFacesDetected = ({ faces }) => { console.log(faces); }; export default App;

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API

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import * as FaceDetector from 'expo-face-detector';

Methods

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Deprecated If you require this functionality, we recommend using react-native-vision-camera

FaceDetector.detectFacesAsync(uri, options)

Android

iOS

| Parameter | Type | Description | | --- | --- | --- | | uri | string | file:// URI to the image. | | options(optional) | [DetectionOptions](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#detectionoptions) | A map of detection options.<br><br>Default:{} |

Detect faces on a picture.

Returns:

[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) <[DetectionResult](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#detectionresult) >

Returns a Promise which fulfils with DetectionResult object.

Types

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DetectionOptions

Android

iOS

In order to configure detector's behavior modules pass a settings object which is then interpreted by this module.

| Property | Type | Description | | --- | --- | --- | | detectLandmarks(optional) | [FaceDetectorLandmarks](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#facedetectorlandmarks) | Whether to detect and return landmarks positions on the face (ears, eyes, mouth, cheeks, nose). Use FaceDetector.FaceDetectorLandmarks.{all, none}. | | minDetectionInterval(optional) | number | Minimal interval in milliseconds between two face detection events being submitted to JS. Use, when you expect lots of faces for long time and are afraid of JS Bridge being overloaded.<br><br>Default:0 | | mode(optional) | [FaceDetectorMode](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#facedetectormode) | Whether to detect faces in fast or accurate mode. Use FaceDetector.FaceDetectorMode.{fast, accurate}. | | runClassifications(optional) | [FaceDetectorClassifications](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#facedetectorclassifications) | Whether to run additional classifications on detected faces (smiling probability, open eye probabilities). Use FaceDetector.FaceDetectorClassifications.{all, none}. | | tracking(optional) | boolean | Flag to enable tracking of faces between frames. If true, each face will be returned with faceID attribute which should be consistent across frames.<br><br>Default:false |

DetectionResult

Android

iOS

| Property | Type | Description | | --- | --- | --- | | faces | [FaceFeature[]](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#facefeature) | Array of faces objects. | | image | [Image](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#image) | - |

FaceFeature

Android

iOS

| Property | Type | Description | | --- | --- | --- | | bottomMouthPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the bottom edge of the mouth in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | bounds | [FaceFeatureBounds](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#facefeaturebounds) | An object containing face bounds. | | faceID(optional) | number | A face identifier (used for tracking, if the same face appears on consecutive frames it will have the same faceID). | | leftCheekPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the left cheek in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | leftEarPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the left ear in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | leftEyeOpenProbability(optional) | number | Probability that the left eye is open. Returned only if detection classifications property is set to FaceDetectorClassifications.all. | | leftEyePosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the left eye in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | leftMouthPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the left edge of the mouth in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | mouthPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the center of the mouth in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | noseBasePosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the nose base in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | rightCheekPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the right cheek in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | rightEarPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the right ear in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | rightEyeOpenProbability(optional) | number | Probability that the right eye is open. Returned only if detection classifications property is set to FaceDetectorClassifications.all. | | rightEyePosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the right eye in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | rightMouthPosition(optional) | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the right edge of the mouth in image coordinates. Returned only if detection classifications property is set to FaceDetectorLandmarks.all. | | rollAngle(optional) | number | Roll angle of the face (bank). | | smilingProbability(optional) | number | Probability that the face is smiling. Returned only if detection classifications property is set to FaceDetectorClassifications.all. | | yawAngle(optional) | number | Yaw angle of the face (heading, turning head left or right). |

FaceFeatureBounds

Android

iOS

| Property | Type | Description | | --- | --- | --- | | origin | [Point](https://docs.expo.dev/versions/v52.0.0/sdk/facedetector#point) | Position of the top left corner of a square containing the face in image coordinates, | | size | { height: number, width: number } | Size of the square containing the face in image coordinates, |

Image

Android

iOS

| Property | Type | Description | | --- | --- | --- | | height | number | Height of the image in pixels. | | orientation | number | Orientation of the image (value conforms to the EXIF orientation tag standard). | | uri | string | URI of the image. | | width | number | Width of the image in pixels. |

Point

Android

iOS

| Property | Type | Description | | --- | --- | --- | | x | number | - | | y | number | - |

Enums

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FaceDetectorClassifications

Android

iOS

none

FaceDetectorClassifications.none ＝ 1

all

FaceDetectorClassifications.all ＝ 2

FaceDetectorLandmarks

Android

iOS

none

FaceDetectorLandmarks.none ＝ 1

all

FaceDetectorLandmarks.all ＝ 2

FaceDetectorMode

Android

iOS

fast

FaceDetectorMode.fast ＝ 1

accurate

FaceDetectorMode.accurate ＝ 2