detectFaces method

Future<DetectFacesResponse> detectFaces({ required Image image, List<Attribute>? attributes, })

Detects faces within an image that is provided as input.

DetectFaces detects the 100 largest faces in the image. For each face detected, the operation returns face details. These details include a bounding box of the face, a confidence value (that the bounding box contains a face), and a fixed set of attributes such as facial landmarks (for example, coordinates of eye and mouth), presence of beard, sunglasses, and so on.

The face-detection algorithm is most effective on frontal faces. For non-frontal or obscured faces, the algorithm might not detect the faces or might detect faces with lower confidence.

You pass the input image either as base64-encoded image bytes or as a reference to an image in an Amazon S3 bucket. If you use the AWS CLI to call Amazon Rekognition operations, passing image bytes is not supported. The image must be either a PNG or JPEG formatted file. This operation requires permissions to perform the rekognition:DetectFaces action.

May throw InvalidS3ObjectException. May throw InvalidParameterException. May throw ImageTooLargeException. May throw AccessDeniedException. May throw InternalServerError. May throw ThrottlingException. May throw ProvisionedThroughputExceededException. May throw InvalidImageFormatException.

Parameter image : The input image as base64-encoded bytes or an S3 object. If you use the AWS CLI to call Amazon Rekognition operations, passing base64-encoded image bytes is not supported.

If you are using an AWS SDK to call Amazon Rekognition, you might not need to base64-encode image bytes passed using the Bytes field. For more information, see Images in the Amazon Rekognition developer guide.

Parameter attributes : An array of facial attributes you want to be returned. This can be the default list of attributes or all attributes. If you don't specify a value for Attributes or if you specify "DEFAULT", the API returns the following subset of facial attributes: BoundingBox, Confidence, Pose, Quality, and Landmarks. If you provide "ALL", all facial attributes are returned, but the operation takes longer to complete.

If you provide both, "ALL", "DEFAULT", the service uses a logical AND operator to determine which attributes to return (in this case, all attributes).

Implementation

Future<DetectFacesResponse> detectFaces({
  required Image image,
  List<Attribute>? attributes,
}) async {
  ArgumentError.checkNotNull(image, 'image');
  final headers = <String, String>{
    'Content-Type': 'application/x-amz-json-1.1',
    'X-Amz-Target': 'RekognitionService.DetectFaces'
  };
  final jsonResponse = await _protocol.send(
    method: 'POST',
    requestUri: '/',
    exceptionFnMap: _exceptionFns,
    // TODO queryParams
    headers: headers,
    payload: {
      'Image': image,
      if (attributes != null)
        'Attributes': attributes.map((e) => e.toValue()).toList(),
    },
  );

  return DetectFacesResponse.fromJson(jsonResponse.body);
}