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Amazon Rekognition
Developer Guide

SearchFacesByImage

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.

Note

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

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, see Example 3: Searching Faces.

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

Request Syntax

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{ "CollectionId": "string", "FaceMatchThreshold": number, "Image": { "Bytes": blob, "S3Object": { "Bucket": "string", "Name": "string", "Version": "string" } }, "MaxFaces": number }

Request Parameters

The request accepts the following data in JSON format.

CollectionId

ID of the collection to search.

Type: String

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

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

Required: Yes

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%.

Type: Float

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

Required: No

Image

The input image as bytes or an S3 object.

Type: Image object

Required: Yes

MaxFaces

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

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

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.

FaceMatches

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

Type: Array of FaceMatch objects

SearchedFaceBoundingBox

The bounding box around the face in the input image that Amazon Rekognition used for the search.

Type: BoundingBox object

SearchedFaceConfidence

The level of confidence that the searchedFaceBoundingBox, contains a face.

Type: Float

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

Errors

AccessDeniedException

You are not authorized to perform the action.

HTTP Status Code: 400

ImageTooLargeException

The input image size exceeds the allowed limit. For more information, see Limits in Amazon Rekognition.

HTTP Status Code: 400

InternalServerError

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

HTTP Status Code: 500

InvalidImageFormatException

The provided image format is not supported.

HTTP Status Code: 400

InvalidParameterException

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

HTTP Status Code: 400

InvalidS3ObjectException

Amazon Rekognition is unable to access the S3 object specified in the request.

HTTP Status Code: 400

ProvisionedThroughputExceededException

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

HTTP Status Code: 400

ResourceNotFoundException

Collection specified in the request is not found.

HTTP Status Code: 400

ThrottlingException

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

HTTP Status Code: 500

Example

Example Request

The following example shows a request that determines the largest face in the supplied image (people.img) and scans a collection (examplemyphotos) for matching faces.

Sample Request

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POST https://rekognition.us-west-2.amazonaws.com/ HTTP/1.1 Host: rekognition.us-west-2.amazonaws.com Accept-Encoding: identity Content-Length: 107 X-Amz-Target: RekognitionService.SearchFacesByImage X-Amz-Date: 20170105T162552Z 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/us-west-2/rekognition/aws4_request, SignedHeaders=content-type;host;x-amz-date;x-amz-target, Signature=XXXXXXXX { "Image":{ "S3Object":{ "Bucket":"example-photos", "Name":"people.jpg" } }, "CollectionId":"examplemyphotos" }

Sample Response

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HTTP/1.1 200 OK Content-Type: application/x-amz-json-1.1 Date: Thu, 05 Jan 2017 16:25:54 GMT x-amzn-RequestId: a0c13bb0-d363-11e6-86be-1d11e90c3f85 Content-Length: 1460 Connection: keep-alive { "FaceMatches":[ { "Face":{ "BoundingBox":{ "Height":0.2220669984817505, "Left":0.5033329725265503, "Top":0.21229000389575958, "Width":0.1766670048236847 }, "Confidence":99.99970245361328, "FaceId":"11111111-2222-3333-4444-555555555555", "ImageId":"11111111-2222-3333-4444-555555555555" }, "Similarity":100.0 }, { "Face":{ "BoundingBox":{ "Height":0.1622219979763031, "Left":0.18942700326442719, "Top":0.008888890035450459, "Width":0.21292200684547424 }, "Confidence":99.96389770507812, "ExternalImageId":"jadenoah2", "FaceId":"11111111-2222-3333-4444-555555555555", "ImageId":"11111111-2222-3333-4444-555555555555" }, "Similarity":95.46002960205078 }, { "Face":{ "BoundingBox":{ "Height":0.09666670113801956, "Left":0.04154299944639206, "Top":0.05444439873099327, "Width":0.12907999753952026 }, "Confidence":99.99909973144531, "ExternalImageId":"jadegarrettelinoah", "FaceId":"11111111-2222-3333-4444-555555555555", "ImageId":"11111111-2222-3333-4444-555555555555" }, "Similarity":92.89849090576172 }, { "Face":{ "BoundingBox":{ "Height":0.11222200095653534, "Left":0.04154299944639206, "Top":0.01888890005648136, "Width":0.149851992726326 }, "Confidence":99.99949645996094, "ExternalImageId":"noahjade", "FaceId":"11111111-2222-3333-4444-555555555555", "ImageId":"11111111-2222-3333-4444-555555555555" }, "Similarity":92.22525787353516 } ], "SearchedFaceBoundingBox":{ "Height":0.22206704318523407, "Left":0.503333330154419, "Top":0.21229049563407898, "Width":0.17666666209697723 }, "SearchedFaceConfidence":99.9996566772461 }

See Also

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