detectCustomLabels method

Future<DetectCustomLabelsResponse> detectCustomLabels({
  1. required Image image,
  2. required String projectVersionArn,
  3. int? maxResults,
  4. double? minConfidence,
})

Detects custom labels in a supplied image by using an Amazon Rekognition Custom Labels model.

You specify which version of a model version to use by using the ProjectVersionArn input parameter.

You pass the input image 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.

For each object that the model version detects on an image, the API returns a (CustomLabel) object in an array (CustomLabels). Each CustomLabel object provides the label name (Name), the level of confidence that the image contains the object (Confidence), and object location information, if it exists, for the label on the image (Geometry).

During training model calculates a threshold value that determines if a prediction for a label is true. By default, DetectCustomLabels doesn't return labels whose confidence value is below the model's calculated threshold value. To filter labels that are returned, specify a value for MinConfidence that is higher than the model's calculated threshold. You can get the model's calculated threshold from the model's training results shown in the Amazon Rekognition Custom Labels console. To get all labels, regardless of confidence, specify a MinConfidence value of 0.

You can also add the MaxResults parameter to limit the number of labels returned.

This is a stateless API operation. That is, the operation does not persist any data.

This operation requires permissions to perform the rekognition:DetectCustomLabels action.

May throw ResourceNotFoundException. May throw ResourceNotReadyException. May throw InvalidS3ObjectException. May throw InvalidParameterException. May throw ImageTooLargeException. May throw LimitExceededException. May throw AccessDeniedException. May throw InternalServerError. May throw ThrottlingException. May throw ProvisionedThroughputExceededException. May throw InvalidImageFormatException.

Parameter projectVersionArn : The ARN of the model version that you want to use.

Parameter maxResults : Maximum number of results you want the service to return in the response. The service returns the specified number of highest confidence labels ranked from highest confidence to lowest.

Parameter minConfidence : Specifies the minimum confidence level for the labels to return. Amazon Rekognition doesn't return any labels with a confidence lower than this specified value. If you specify a value of 0, all labels are return, regardless of the default thresholds that the model version applies.

Implementation

Future<DetectCustomLabelsResponse> detectCustomLabels({
  required Image image,
  required String projectVersionArn,
  int? maxResults,
  double? minConfidence,
}) async {
  ArgumentError.checkNotNull(image, 'image');
  ArgumentError.checkNotNull(projectVersionArn, 'projectVersionArn');
  _s.validateStringLength(
    'projectVersionArn',
    projectVersionArn,
    20,
    2048,
    isRequired: true,
  );
  _s.validateNumRange(
    'maxResults',
    maxResults,
    0,
    1152921504606846976,
  );
  _s.validateNumRange(
    'minConfidence',
    minConfidence,
    0,
    100,
  );
  final headers = <String, String>{
    'Content-Type': 'application/x-amz-json-1.1',
    'X-Amz-Target': 'RekognitionService.DetectCustomLabels'
  };
  final jsonResponse = await _protocol.send(
    method: 'POST',
    requestUri: '/',
    exceptionFnMap: _exceptionFns,
    // TODO queryParams
    headers: headers,
    payload: {
      'Image': image,
      'ProjectVersionArn': projectVersionArn,
      if (maxResults != null) 'MaxResults': maxResults,
      if (minConfidence != null) 'MinConfidence': minConfidence,
    },
  );

  return DetectCustomLabelsResponse.fromJson(jsonResponse.body);
}