Amazon Rekognition
Developer Guide


For a given input face ID, searches for matching faces in the collection the face belongs to. You get a face ID when you add a face to the collection using the IndexFaces operation. The operation compares the features of the input face with faces in the specified collection.


You can also search faces without indexing faces by using the SearchFacesByImage operation.

The operation 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 that is found. Along with the metadata, the response also includes a confidence value for each face match, indicating the confidence that the specific face matches the input face.

For an example, see Example 3: Searching Faces.

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

Request Syntax

{ "CollectionId": "string", "FaceId": "string", "FaceMatchThreshold": number, "MaxFaces": number }

Request Parameters

The request accepts the following data in JSON format.


ID of the collection the face belongs to.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 255.

Pattern: [a-zA-Z0-9_.\-]+

Required: Yes


ID of a face to find matches for in the collection.

Type: String

Pattern: [0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}

Required: Yes


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

Type: Float

Valid Range: Minimum value of 0. Maximum value of 100.

Required: No


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

Type: Integer

Valid Range: Minimum value of 1. Maximum value of 4096.

Required: No

Response Syntax

{ "FaceMatches": [ { "Face": { "BoundingBox": { "Height": number, "Left": number, "Top": number, "Width": number }, "Confidence": number, "ExternalImageId": "string", "FaceId": "string", "ImageId": "string" }, "Similarity": number } ], "SearchedFaceId": "string" }

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.


An array of faces that matched the input face, along with the confidence in the match.

Type: Array of FaceMatch objects


ID of the face that was searched for matches in a collection.

Type: String

Pattern: [0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}



You are not authorized to perform the action.

HTTP Status Code: 400


Amazon Rekognition experienced a service issue. Try your call again.

HTTP Status Code: 500


Input parameter violated a constraint. Validate your parameter before calling the API operation again.

HTTP Status Code: 400


The number of requests exceeded your throughput limit. If you want to increase this limit, contact Amazon Rekognition.

HTTP Status Code: 400


Collection specified in the request is not found.

HTTP Status Code: 400


Amazon Rekognition is temporarily unable to process the request. Try your call again.

HTTP Status Code: 500


Example Request

The following example shows a request that searches for occurrences of a face within the collection (examplemyphotos) the face belongs to.

Sample Request

POST HTTP/1.1 Host: Accept-Encoding: identity Content-Length: 78 X-Amz-Target: RekognitionService.SearchFaces X-Amz-Date: 20170105T163206Z User-Agent: aws-cli/1.11.25 Python/2.7.9 Windows/8 botocore/1.4.82 Content-Type: application/x-amz-json-1.1 Authorization: AWS4-HMAC-SHA256 Credential=XXXXXXXX/20170105/us-west-2/rekognition/aws4_request, SignedHeaders=content-type;host;x-amz-date;x-amz-target, Signature=XXXXXXXX { "FaceId":"11111111-2222-3333-4444-555555555555", "CollectionId":"examplemyphotos" }

Sample Response

HTTP/1.1 200 OK Content-Type: application/x-amz-json-1.1 Date: Thu, 05 Jan 2017 16:32:08 GMT x-amzn-RequestId: 80269055-d364-11e6-9e9d-9b236fb2a3ad Content-Length: 1057 Connection: keep-alive { "FaceMatches":[ { "Face":{ "BoundingBox":{ "Height":0.1622219979763031, "Left":0.18942700326442719, "Top":0.008888890035450459, "Width":0.21292200684547424 }, "Confidence":99.96389770507812, "ExternalImageId":"externalimageidONE", "FaceId":"11111111-2222-3333-4444-555555555555", "ImageId":"11111111-2222-3333-4444-555555555555" }, "Similarity":95.46002197265625 }, { "Face":{ "BoundingBox":{ "Height":0.09666670113801956, "Left":0.04154299944639206, "Top":0.05444439873099327, "Width":0.12907999753952026 }, "Confidence":99.99909973144531, "ExternalImageId":"externalimageidTWO", "FaceId":"22222222-2222-3333-4444-555555555555", "ImageId":"22222222-2222-3333-4444-555555555555" }, "Similarity":92.89849090576172 }, { "Face":{ "BoundingBox":{ "Height":0.11222200095653534, "Left":0.04154299944639206, "Top":0.01888890005648136, "Width":0.149851992726326 }, "Confidence":99.99949645996094, "ExternalImageId":"externalimageidTHREE", "FaceId":"11111111-2222-3333-4444-555555555555", "ImageId":"11111111-2222-3333-4444-555555555555" }, "Similarity":92.22525024414062 } ], "SearchedFaceId":"11111111-2222-3333-4444-555555555555" }

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: