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Detects faces in the input image and adds them to the specified collection.
Amazon Rekognition doesn't save the actual faces that are detected. Instead, the underlying detection algorithm first detects the faces in the input image. For each face, the algorithm extracts facial features into a feature vector, and stores it in the backend database. Amazon Rekognition uses feature vectors when it performs face match and search operations using the SearchFaces and SearchFacesByImage operations.
For more information, see Adding faces to a collection in the Amazon Rekognition Developer Guide.
To get the number of faces in a collection, call DescribeCollection.
If you're using version 1.0 of the face detection model, IndexFaces indexes
the 15 largest faces in the input image. Later versions of the face detection model
index the 100 largest faces in the input image.
If you're using version 4 or later of the face model, image orientation information
is not returned in the OrientationCorrection field.
To determine which version of the model you're using, call DescribeCollection
and supply the collection ID. You can also get the model version from the value of
FaceModelVersion in the response from IndexFaces
For more information, see Model Versioning in the Amazon Rekognition Developer Guide.
If you provide the optional ExternalImageId for the input image you provided,
Amazon Rekognition associates this ID with all faces that it detects. When you call
the ListFaces operation, the response returns the external ID. You can use
this external image ID to create a client-side index to associate the faces with each
image. You can then use the index to find all faces in an image.
You can specify the maximum number of faces to index with the MaxFaces input
parameter. This is useful when you want to index the largest faces in an image and
don't want to index smaller faces, such as those belonging to people standing in the
background.
The QualityFilter input parameter allows you to filter out detected faces that
don’t meet a required quality bar. The quality bar is based on a variety of common
use cases. By default, IndexFaces chooses the quality bar that's used to filter
faces. You can also explicitly choose the quality bar. Use QualityFilter, to
set the quality bar by specifying LOW, MEDIUM, or HIGH. If you
do not want to filter detected faces, specify NONE.
To use quality filtering, you need a collection associated with version 3 of the face model or higher. To get the version of the face model associated with a collection, call DescribeCollection.
Information about faces detected in an image, but not indexed, is returned in an array
of UnindexedFace objects, UnindexedFaces. Faces aren't indexed for reasons
such as:
The number of faces detected exceeds the value of the MaxFaces request parameter.
The face is too small compared to the image dimensions.
The face is too blurry.
The image is too dark.
The face has an extreme pose.
The face doesn’t have enough detail to be suitable for face search.
In response, the IndexFaces operation returns an array of metadata for all
detected faces, FaceRecords. This includes:
The bounding box, BoundingBox, of the detected face.
A confidence value, Confidence, which indicates the confidence that the bounding
box contains a face.
A face ID, FaceId, assigned by the service for each face that's detected and
stored.
An image ID, ImageId, assigned by the service for the input image.
If you request ALL or specific facial attributes (e.g., FACE_OCCLUDED)
by using the detectionAttributes parameter, Amazon Rekognition returns detailed facial
attributes, such as facial landmarks (for example, location of eye and mouth), facial
occlusion, and other facial attributes.
If you provide the same image, specify the same collection, and use the same external
ID in the IndexFaces operation, Amazon Rekognition doesn't save duplicate face
metadata.
The input image is passed 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 isn't supported. The image must be formatted as a PNG or JPEG file.
This operation requires permissions to perform the rekognition:IndexFaces action.
This is an asynchronous operation using the standard naming convention for .NET 4.5 or higher. For .NET 3.5 the operation is implemented as a pair of methods using the standard naming convention of BeginIndexFaces and EndIndexFaces.
Namespace: Amazon.Rekognition
Assembly: AWSSDK.Rekognition.dll
Version: 3.x.y.z
public virtual Task<IndexFacesResponse> IndexFacesAsync( IndexFacesRequest request, CancellationToken cancellationToken )
Container for the necessary parameters to execute the IndexFaces service method.
A cancellation token that can be used by other objects or threads to receive notice of cancellation.
| Exception | Condition |
|---|---|
| AccessDeniedException | You are not authorized to perform the action. |
| ImageTooLargeException | The input image size exceeds the allowed limit. If you are calling DetectProtectiveEquipment, the image size or resolution exceeds the allowed limit. For more information, see Guidelines and quotas in Amazon Rekognition in the Amazon Rekognition Developer Guide. |
| InternalServerErrorException | Amazon Rekognition experienced a service issue. Try your call again. |
| InvalidImageFormatException | The provided image format is not supported. |
| InvalidParameterException | Input parameter violated a constraint. Validate your parameter before calling the API operation again. |
| InvalidS3ObjectException | Amazon Rekognition is unable to access the S3 object specified in the request. |
| ProvisionedThroughputExceededException | The number of requests exceeded your throughput limit. If you want to increase this limit, contact Amazon Rekognition. |
| ResourceNotFoundException | The resource specified in the request cannot be found. |
| ServiceQuotaExceededException | The size of the collection exceeds the allowed limit. For more information, see Guidelines and quotas in Amazon Rekognition in the Amazon Rekognition Developer Guide. |
| ThrottlingException | Amazon Rekognition is temporarily unable to process the request. Try your call again. |
.NET Core App:
Supported in: 3.1
.NET Standard:
Supported in: 2.0
.NET Framework:
Supported in: 4.5