顯示週框方塊

Amazon Rekognition Image 操作可以針對映像中偵測到的專案傳回週框方塊。例如，此DetectFaces作業會針對影像中偵測到的每個臉部傳回邊界方框 (BoundingBox)。您可以使用週框方塊座標，來顯示所偵測到之專案的周圍方塊。例如，以下映像會顯示圍繞人臉的週框方塊。

BoundingBox 具有下列屬性：

• 高度：週框方塊的高度，以整體映像高度的比例表示。

• 左邊：週框方塊的左邊座標，以整體映像寬度的比例表示。

• 上方：週框方塊的上方座標，以整體映像高度的比例表示。

• 寬度：週框方塊的寬度，以整體映像寬度的比例表示。

每個 BoundingBox 屬性都有一個介於 0 和 1 之間的值。每個屬性值是整體映像寬度 (Left 和 Width) 或高度 (Height 和 Top) 的比例。例如，如果輸入映像為 700 x 200 像素，而週框方塊的左上方座標為 350 x 50 像素，則 API 會傳回 Left 值 0.5 (350/700) 和 Top 值 0.25 (50/200)。

下圖顯示每個週框方塊屬性涵蓋的映像範圍。

要顯示具有正確位置和大小的邊界框，您必須將 BoundingBox 值乘以圖像寬度或高度（取決於您想要的值）才能獲得像素值。您可以使用像素值來顯示週框方塊。例如，前一個映像的像素維度為 608 寬度 x 588 高度。臉部的週框方塊值如下：

BoundingBox.Left: 0.3922065
BoundingBox.Top: 0.15567766
BoundingBox.Width: 0.284666
BoundingBox.Height: 0.2930403

臉部週框方塊的位置 (以像素表示) 的計算方式如下：

Left coordinate = BoundingBox.Left (0.3922065) * image width (608) = 238

Top coordinate = BoundingBox.Top (0.15567766) * image height (588) = 91

Face width = BoundingBox.Width (0.284666) * image width (608) = 173

Face height = BoundingBox.Height (0.2930403) * image height (588) = 172

您可以使用這些值來顯示臉部的週框方塊。

注意

您可以透過多種方式導向映像。您的應用程式可能需要旋轉映像，才能以正確方向顯示它。週框方塊座標會受到映像方向的影響。您可能需要轉換座標，然後才能在正確位置顯示週框方塊。如需詳細資訊，請參閱 取得映像方向與週框方塊座標。

下列範例顯示如何在透過呼叫偵測到的面周圍顯示邊界方塊DetectFaces。這些範例假設映像導向至 0 度。這些範例也會顯示如何從 Amazon S3 儲存貯體下載映像。

顯示週框方塊

1. 如果您尚未執行：

   1. 建立或更新具有 AmazonRekognitionFullAccess 和 AmazonS3ReadOnlyAccess 許可的使用者。如需詳細資訊，請參閱 步驟 1：設定 AWS 帳戶並建立使用者。

   2. 安裝和設定 AWS CLI AWS 軟體開發套件。如需詳細資訊，請參閱 步驟 2：設定 AWS CLI 和開 AWS 發套件。

2. 使用下列範例來呼叫 DetectFaces 操作。

   Java

   將 bucket 的值變更為包含映像檔案的 Amazon S3 儲存貯體。將 photo 的值變更為某個映像檔案的檔案名稱 (.jpg 或 .png 格式)。

    
   //Loads images, detects faces and draws bounding boxes.Determines exif orientation, if necessary.
   package com.amazonaws.samples;
   
   //Import the basic graphics classes.
   import java.awt.*;
   import java.awt.image.BufferedImage;
   import java.util.List;
   import javax.imageio.ImageIO;
   import javax.swing.*;
   
   import com.amazonaws.services.rekognition.AmazonRekognition;
   import com.amazonaws.services.rekognition.AmazonRekognitionClientBuilder;
   
   import com.amazonaws.services.rekognition.model.BoundingBox;
   import com.amazonaws.services.rekognition.model.DetectFacesRequest;
   import com.amazonaws.services.rekognition.model.DetectFacesResult;
   import com.amazonaws.services.rekognition.model.FaceDetail;
   import com.amazonaws.services.rekognition.model.Image;
   import com.amazonaws.services.rekognition.model.S3Object;
   import com.amazonaws.services.s3.AmazonS3;
   import com.amazonaws.services.s3.AmazonS3ClientBuilder;
   import com.amazonaws.services.s3.model.S3ObjectInputStream;
   
   // Calls DetectFaces and displays a bounding box around each detected image.
   public class DisplayFaces extends JPanel {
   
       private static final long serialVersionUID = 1L;
   
       BufferedImage image;
       static int scale;
       DetectFacesResult result;
   
       public DisplayFaces(DetectFacesResult facesResult, BufferedImage bufImage) throws Exception {
           super();
           scale = 1; // increase to shrink image size.
   
           result = facesResult;
           image = bufImage;
   
           
       }
       // Draws the bounding box around the detected faces.
       public void paintComponent(Graphics g) {
           float left = 0;
           float top = 0;
           int height = image.getHeight(this);
           int width = image.getWidth(this);
   
           Graphics2D g2d = (Graphics2D) g; // Create a Java2D version of g.
   
           // Draw the image.
           g2d.drawImage(image, 0, 0, width / scale, height / scale, this);
           g2d.setColor(new Color(0, 212, 0));
   
           // Iterate through faces and display bounding boxes.
           List<FaceDetail> faceDetails = result.getFaceDetails();
           for (FaceDetail face : faceDetails) {
               
               BoundingBox box = face.getBoundingBox();
               left = width * box.getLeft();
               top = height * box.getTop();
               g2d.drawRect(Math.round(left / scale), Math.round(top / scale),
                       Math.round((width * box.getWidth()) / scale), Math.round((height * box.getHeight())) / scale);
               
           }
       }
   
   
       public static void main(String arg[]) throws Exception {
   
           String photo = "photo.png";
           String bucket = "bucket";
           int height = 0;
           int width = 0;
   
           // Get the image from an S3 Bucket
           AmazonS3 s3client = AmazonS3ClientBuilder.defaultClient();
   
           com.amazonaws.services.s3.model.S3Object s3object = s3client.getObject(bucket, photo);
           S3ObjectInputStream inputStream = s3object.getObjectContent();
           BufferedImage image = ImageIO.read(inputStream);
           DetectFacesRequest request = new DetectFacesRequest()
                   .withImage(new Image().withS3Object(new S3Object().withName(photo).withBucket(bucket)));
   
           width = image.getWidth();
           height = image.getHeight();
   
           // Call DetectFaces    
           AmazonRekognition amazonRekognition = AmazonRekognitionClientBuilder.defaultClient();
           DetectFacesResult result = amazonRekognition.detectFaces(request);
           
           //Show the bounding box info for each face.
           List<FaceDetail> faceDetails = result.getFaceDetails();
           for (FaceDetail face : faceDetails) {
   
               BoundingBox box = face.getBoundingBox();
               float left = width * box.getLeft();
               float top = height * box.getTop();
               System.out.println("Face:");
   
               System.out.println("Left: " + String.valueOf((int) left));
               System.out.println("Top: " + String.valueOf((int) top));
               System.out.println("Face Width: " + String.valueOf((int) (width * box.getWidth())));
               System.out.println("Face Height: " + String.valueOf((int) (height * box.getHeight())));
               System.out.println();
   
           }
   
           // Create frame and panel.
           JFrame frame = new JFrame("RotateImage");
           frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           DisplayFaces panel = new DisplayFaces(result, image);
           panel.setPreferredSize(new Dimension(image.getWidth() / scale, image.getHeight() / scale));
           frame.setContentPane(panel);
           frame.pack();
           frame.setVisible(true);
   
       }
   }
    

   Python

   將 bucket 的值變更為包含映像檔案的 Amazon S3 儲存貯體。將 photo 的值變更為某個映像檔案的檔案名稱 (.jpg 或 .png 格式)。將建立 Rekognition 工作階段的行中 profile_name 值取代為您開發人員設定檔的名稱。

   import boto3
   import io
   from PIL import Image, ImageDraw
   
   def show_faces(photo, bucket):
   
       session = boto3.Session(profile_name='profile-name')
       client = session.client('rekognition')
   
       # Load image from S3 bucket
       s3_connection = boto3.resource('s3')
       s3_object = s3_connection.Object(bucket, photo)
       s3_response = s3_object.get()
   
       stream = io.BytesIO(s3_response['Body'].read())
       image = Image.open(stream)
   
       # Call DetectFaces
       response = client.detect_faces(Image={'S3Object': {'Bucket': bucket, 'Name': photo}},
                                      Attributes=['ALL'])
   
       imgWidth, imgHeight = image.size
       draw = ImageDraw.Draw(image)
   
       # calculate and display bounding boxes for each detected face
       print('Detected faces for ' + photo)
       for faceDetail in response['FaceDetails']:
           print('The detected face is between ' + str(faceDetail['AgeRange']['Low'])
                 + ' and ' + str(faceDetail['AgeRange']['High']) + ' years old')
   
           box = faceDetail['BoundingBox']
           left = imgWidth * box['Left']
           top = imgHeight * box['Top']
           width = imgWidth * box['Width']
           height = imgHeight * box['Height']
   
           print('Left: ' + '{0:.0f}'.format(left))
           print('Top: ' + '{0:.0f}'.format(top))
           print('Face Width: ' + "{0:.0f}".format(width))
           print('Face Height: ' + "{0:.0f}".format(height))
   
           points = (
               (left, top),
               (left + width, top),
               (left + width, top + height),
               (left, top + height),
               (left, top)
   
           )
           draw.line(points, fill='#00d400', width=2)
   
           # Alternatively can draw rectangle. However you can't set line width.
           # draw.rectangle([left,top, left + width, top + height], outline='#00d400')
   
       image.show()
   
       return len(response['FaceDetails'])
   
   def main():
       bucket = "bucket-name"
       photo = "photo-name"
       faces_count = show_faces(photo, bucket)
       print("faces detected: " + str(faces_count))
   
   if __name__ == "__main__":
       main()

   Java V2

   此代碼取自 AWS 文檔 SDK 示例 GitHub 存儲庫。請參閱此處的完整範例。

   請注意，s3 是指 AWS SDK Amazon Amazon S3 客戶端，并且 rekClient 是指 AWS SDK Amazon Rekognition 客戶端。

   //snippet-start:[rekognition.java2.detect_labels.import]
   import java.awt.*;
   import java.awt.image.BufferedImage;
   import java.io.ByteArrayInputStream;
   import java.io.FileNotFoundException;
   import java.io.IOException;
   import java.io.InputStream;
   import java.util.List;
   import javax.imageio.ImageIO;
   import javax.swing.*;
   import software.amazon.awssdk.auth.credentials.ProfileCredentialsProvider;
   import software.amazon.awssdk.core.ResponseBytes;
   import software.amazon.awssdk.core.SdkBytes;
   import software.amazon.awssdk.regions.Region;
   import software.amazon.awssdk.services.rekognition.model.Attribute;
   import software.amazon.awssdk.services.rekognition.model.BoundingBox;
   import software.amazon.awssdk.services.rekognition.model.DetectFacesRequest;
   import software.amazon.awssdk.services.rekognition.model.DetectFacesResponse;
   import software.amazon.awssdk.services.rekognition.model.FaceDetail;
   import software.amazon.awssdk.services.rekognition.model.Image;
   import software.amazon.awssdk.services.rekognition.model.RekognitionException;
   import software.amazon.awssdk.services.s3.S3Client;
   import software.amazon.awssdk.services.rekognition.RekognitionClient;
   import software.amazon.awssdk.services.s3.model.GetObjectRequest;
   import software.amazon.awssdk.services.s3.model.GetObjectResponse;
   import software.amazon.awssdk.services.s3.model.S3Exception;
   //snippet-end:[rekognition.java2.detect_labels.import]
   
   /**
   * Before running this Java V2 code example, set up your development environment, including your credentials.
   *
   * For more information, see the following documentation topic:
   *
   * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
   */
   public class DisplayFaces extends JPanel {
   
       static DetectFacesResponse result;
       static BufferedImage image;
       static int scale;
   
       public static void main(String[] args) throws Exception {
   
           final String usage = "\n" +
               "Usage: " +
               "   <sourceImage> <bucketName>\n\n" +
               "Where:\n" +
               "   sourceImage - The name of the image in an Amazon S3 bucket (for example, people.png). \n\n" +
               "   bucketName - The name of the Amazon S3 bucket (for example, myBucket). \n\n";
   
           if (args.length != 2) {
               System.out.println(usage);
               System.exit(1);
           }
   
           String sourceImage = args[0];
           String bucketName = args[1];
           Region region = Region.US_EAST_1;
           S3Client s3 = S3Client.builder()
               .region(region)
               .credentialsProvider(ProfileCredentialsProvider.create("profile-name"))
               .build();
   
           RekognitionClient rekClient = RekognitionClient.builder()
               .region(region)
               .credentialsProvider(ProfileCredentialsProvider.create("profile-name"))
               .build();
   
           displayAllFaces(s3, rekClient, sourceImage, bucketName);
           s3.close();
           rekClient.close();
       }
   
       // snippet-start:[rekognition.java2.display_faces.main]
       public static void displayAllFaces(S3Client s3,
                                          RekognitionClient rekClient,
                                          String sourceImage,
                                          String bucketName) {
           int height;
           int width;
           byte[] data = getObjectBytes (s3, bucketName, sourceImage);
           InputStream is = new ByteArrayInputStream(data);
   
           try {
               SdkBytes sourceBytes = SdkBytes.fromInputStream(is);
               image = ImageIO.read(sourceBytes.asInputStream());
               width = image.getWidth();
               height = image.getHeight();
   
               // Create an Image object for the source image
               software.amazon.awssdk.services.rekognition.model.Image souImage = Image.builder()
                   .bytes(sourceBytes)
                   .build();
   
               DetectFacesRequest facesRequest = DetectFacesRequest.builder()
                   .attributes(Attribute.ALL)
                   .image(souImage)
                   .build();
   
               result = rekClient.detectFaces(facesRequest);
   
               // Show the bounding box info for each face.
               List<FaceDetail> faceDetails = result.faceDetails();
               for (FaceDetail face : faceDetails) {
                   BoundingBox box = face.boundingBox();
                   float left = width * box.left();
                   float top = height * box.top();
                   System.out.println("Face:");
   
                   System.out.println("Left: " + (int) left);
                   System.out.println("Top: " + (int) top);
                   System.out.println("Face Width: " + (int) (width * box.width()));
                   System.out.println("Face Height: " + (int) (height * box.height()));
                   System.out.println();
               }
   
               // Create the frame and panel.
               JFrame frame = new JFrame("RotateImage");
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               DisplayFaces panel = new DisplayFaces(image);
               panel.setPreferredSize(new Dimension(image.getWidth() / scale, image.getHeight() / scale));
               frame.setContentPane(panel);
               frame.pack();
               frame.setVisible(true);
   
           } catch (RekognitionException | FileNotFoundException e) {
               System.out.println(e.getMessage());
               System.exit(1);
           } catch (IOException e) {
              e.printStackTrace();
           }
       }
   
       public static byte[] getObjectBytes (S3Client s3, String bucketName, String keyName) {
   
           try {
               GetObjectRequest objectRequest = GetObjectRequest
                   .builder()
                   .key(keyName)
                   .bucket(bucketName)
                   .build();
   
               ResponseBytes<GetObjectResponse> objectBytes = s3.getObjectAsBytes(objectRequest);
               return objectBytes.asByteArray();
   
           } catch (S3Exception e) {
               System.err.println(e.awsErrorDetails().errorMessage());
               System.exit(1);
           }
           return null;
       }
   
       public DisplayFaces(BufferedImage bufImage) {
           super();
           scale = 1; // increase to shrink image size.
           image = bufImage;
       }
   
       // Draws the bounding box around the detected faces.
       public void paintComponent(Graphics g) {
           float left;
           float top;
           int height = image.getHeight(this);
           int width = image.getWidth(this);
           Graphics2D g2d = (Graphics2D) g; // Create a Java2D version of g.
   
           // Draw the image
           g2d.drawImage(image, 0, 0, width / scale, height / scale, this);
           g2d.setColor(new Color(0, 212, 0));
   
           // Iterate through the faces and display bounding boxes.
           List<FaceDetail> faceDetails = result.faceDetails();
           for (FaceDetail face : faceDetails) {
               BoundingBox box = face.boundingBox();
               left = width * box.left();
               top = height * box.top();
               g2d.drawRect(Math.round(left / scale), Math.round(top / scale),
                       Math.round((width * box.width()) / scale), Math.round((height * box.height())) / scale);
           }
       }
       // snippet-end:[rekognition.java2.display_faces.main]
   }