AWS SDK Version 3 for .NET
API Reference

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Container for the parameters to the SearchFacesByImage operation. For a given input image, first detects the largest face in the image, and then searches the specified collection for matching faces. The operation compares the features of the input face with faces in the specified collection.

To search for all faces in an input image, you might first call the operation, and then use the face IDs returned in subsequent calls to the operation.

You can also call the DetectFaces operation and use the bounding boxes in the response to make face crops, which then you can pass in to the SearchFacesByImage operation.

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 Amazon CLI to call Amazon Rekognition operations, passing image bytes is not supported. The image must be either a PNG or JPEG formatted file.

The response returns an array of faces that match, ordered by similarity score with the highest similarity first. More specifically, it is an array of metadata for each face match found. Along with the metadata, the response also includes a similarity indicating how similar the face is to the input face. In the response, the operation also returns the bounding box (and a confidence level that the bounding box contains a face) of the face that Amazon Rekognition used for the input image.

For an example, Searching for a Face Using an Image in the Amazon Rekognition Developer Guide.

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

Inheritance Hierarchy


Namespace: Amazon.Rekognition.Model
Assembly: AWSSDK.Rekognition.dll
Version: 3.x.y.z


public class SearchFacesByImageRequest : AmazonRekognitionRequest

The SearchFacesByImageRequest type exposes the following members


Public Method SearchFacesByImageRequest()


Public Property CollectionId System.String

Gets and sets the property CollectionId.

ID of the collection to search.

Public Property FaceMatchThreshold System.Single

Gets and sets the property FaceMatchThreshold.

(Optional) Specifies the minimum confidence in the face match to return. For example, don't return any matches where confidence in matches is less than 70%.

Public Property Image Amazon.Rekognition.Model.Image

Gets and sets the property 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.

Public Property MaxFaces System.Int32

Gets and sets the property MaxFaces.

Maximum number of faces to return. The operation returns the maximum number of faces with the highest confidence in the match.


This operation searches for faces in a Rekognition collection that match the largest face in an S3 bucket stored image.

To search for faces matching a supplied image

var response = client.SearchFacesByImage(new SearchFacesByImageRequest 
    CollectionId = "myphotos",
    FaceMatchThreshold = 95,
    Image = new Image { S3Object = new S3Object {
        Bucket = "mybucket",
        Name = "myphoto"
    } },
    MaxFaces = 5

List faceMatches = response.FaceMatches;
BoundingBox searchedFaceBoundingBox = response.SearchedFaceBoundingBox;
float searchedFaceConfidence = response.SearchedFaceConfidence;


Version Information

.NET Standard:
Supported in: 1.3

.NET Framework:
Supported in: 4.5, 4.0, 3.5

Portable Class Library:
Supported in: Windows Store Apps
Supported in: Windows Phone 8.1
Supported in: Xamarin Android
Supported in: Xamarin iOS (Unified)
Supported in: Xamarin.Forms