// snippet-sourcedescription:[CompareFaces.java demonstrates how to compare 2 faces.]
// snippet-service:[Amazon Rekognition]
// snippet-keyword:[Java]
// snippet-keyword:[Amazon Rekognition]
// snippet-keyword:[Code Sample]
// snippet-sourcetype:[full-example]
// snippet-sourcedate:[6-10-2020]
// snippet-sourceauthor:[scmacdon - AWS]

/**
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * This file is licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License. A copy of
 * the License is located at
 *
 * http://aws.amazon.com/apache2.0/
 *
 * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */

package com.example.rekognition;

// snippet-start:[rekognition.java2.compare_faces.import]
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.rekognition.RekognitionClient;
import software.amazon.awssdk.services.rekognition.model.RekognitionException;
import software.amazon.awssdk.services.rekognition.model.Image;
import software.amazon.awssdk.services.rekognition.model.CompareFacesRequest;
import software.amazon.awssdk.services.rekognition.model.CompareFacesResponse;
import software.amazon.awssdk.services.rekognition.model.CompareFacesMatch;
import software.amazon.awssdk.services.rekognition.model.ComparedFace;
import software.amazon.awssdk.services.rekognition.model.BoundingBox;
import software.amazon.awssdk.core.SdkBytes;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.List;
// snippet-end:[rekognition.java2.compare_faces.import]


public class CompareFaces {

    public static void main(String[] args) {

        final String USAGE = "\n" +
                "CompareFaces - how to compare two faces in two images\n\n" +
                "Usage: CompareFaces <pathSource> <pathTarget>\n\n" +
                "Where:\n" +
                "pathSource - the path to the source image (ie, C:\\AWS\\pic1.png) \n " +
                "pathTarget - the path to the target image (ie, C:\\AWS\\pic2.png) \n\n";

        Float similarityThreshold = 70F;
        String sourceImage = args[0];
        String targetImage = args[1];

        Region region = Region.US_EAST_2;
        RekognitionClient rekClient = RekognitionClient.builder()
                .region(region)
                .build();

        compareTwoFaces(rekClient, similarityThreshold, sourceImage, targetImage);
   }

    // snippet-start:[rekognition.java2.compare_faces.main]
    public static void compareTwoFaces(RekognitionClient rekClient, Float similarityThreshold, String sourceImage, String targetImage) {

        try {
            InputStream sourceStream = new FileInputStream(new File(sourceImage));
            InputStream tarStream = new FileInputStream(new File(targetImage));

            SdkBytes sourceBytes = SdkBytes.fromInputStream(sourceStream);
            SdkBytes targetBytes = SdkBytes.fromInputStream(tarStream);

            // Create an Image object for the source image
            Image souImage = Image.builder()
            .bytes(sourceBytes)
            .build();

            // Create an Image object for the target image
            Image tarImage = Image.builder()
                    .bytes(targetBytes)
                    .build();

            // Create a CompareFacesRequest object
            CompareFacesRequest facesRequest = CompareFacesRequest.builder()
                    .sourceImage(souImage)
                    .targetImage(tarImage)
                    .similarityThreshold(similarityThreshold)
                    .build();

            // Compare the two images
            CompareFacesResponse compareFacesResult = rekClient.compareFaces(facesRequest);

            // Display results
            List<CompareFacesMatch> faceDetails = compareFacesResult.faceMatches();
            for (CompareFacesMatch match: faceDetails){
                ComparedFace face= match.face();
                BoundingBox position = face.boundingBox();
                System.out.println("Face at " + position.left().toString()
                        + " " + position.top()
                        + " matches with " + face.confidence().toString()
                        + "% confidence.");

            }
            List<ComparedFace> uncompared = compareFacesResult.unmatchedFaces();

            System.out.println("There was " + uncompared.size()
                    + " face(s) that did not match");
            System.out.println("Source image rotation: " + compareFacesResult.sourceImageOrientationCorrection());
            System.out.println("target image rotation: " + compareFacesResult.targetImageOrientationCorrection());

        } catch(RekognitionException | FileNotFoundException e) {
            System.out.println("Failed to load source image " + sourceImage);
            System.exit(1);
        }
        // snippet-end:[rekognition.java2.compare_faces.main]
    }
}

Create CompareFaces.java