MLKit Firebase android - How to convert FirebaseVisionFace to Image Object (like Bitmap)?

Question

I have integrated MLkit FaceDetection into my android application. I have referred below URL

https://firebase.google.com/docs/ml-kit/android/detect-faces

Code for Face Detection Processor Class is

import java.io.IOException;
import java.util.List;

/** Face Detector Demo. */
public class FaceDetectionProcessor extends VisionProcessorBase<List<FirebaseVisionFace>> {

  private static final String TAG = "FaceDetectionProcessor";

  private final FirebaseVisionFaceDetector detector;

  public FaceDetectionProcessor() {

    FirebaseVisionFaceDetectorOptions options =
        new FirebaseVisionFaceDetectorOptions.Builder()
            .setClassificationType(FirebaseVisionFaceDetectorOptions.ALL_CLASSIFICATIONS)
            .setLandmarkType(FirebaseVisionFaceDetectorOptions.ALL_LANDMARKS)
            .setTrackingEnabled(true)
            .build();

    detector = FirebaseVision.getInstance().getVisionFaceDetector(options);
  }

  @Override
  public void stop() {
    try {
      detector.close();
    } catch (IOException e) {
      Log.e(TAG, "Exception thrown while trying to close Face Detector: " + e);
    }
  }

  @Override
  protected Task<List<FirebaseVisionFace>> detectInImage(FirebaseVisionImage image) {
    return detector.detectInImage(image);
  }

  @Override
  protected void onSuccess(
      @NonNull List<FirebaseVisionFace> faces,
      @NonNull FrameMetadata frameMetadata,
      @NonNull GraphicOverlay graphicOverlay) {
      graphicOverlay.clear();

    for (int i = 0; i < faces.size(); ++i) {
      FirebaseVisionFace face = faces.get(i);
      FaceGraphic faceGraphic = new FaceGraphic(graphicOverlay);
      graphicOverlay.add(faceGraphic);
      faceGraphic.updateFace(face, frameMetadata.getCameraFacing());
    }




  }

  @Override
  protected void onFailure(@NonNull Exception e) {
    Log.e(TAG, "Face detection failed " + e);
  }
}

Here in "onSuccess" listener , we will get array of "FirebaseVisionFace" class objects which will have "Bounding Box" of face.

@Override
      protected void onSuccess(
          @NonNull List<FirebaseVisionFace> faces,
          @NonNull FrameMetadata frameMetadata,
          @NonNull GraphicOverlay graphicOverlay) {
          graphicOverlay.clear();

        for (int i = 0; i < faces.size(); ++i) {
          FirebaseVisionFace face = faces.get(i);
          FaceGraphic faceGraphic = new FaceGraphic(graphicOverlay);
          graphicOverlay.add(faceGraphic);
          faceGraphic.updateFace(face, frameMetadata.getCameraFacing());
        }
      }

I want to know How to convert this FirebaseVisionFace objects into Bitmap. I want to extract face image and show it in ImageView. Can anyone please help me . Thanks in advance.

Note : I have downloaded the sample Source code of MLKit android from below URL

https://github.com/firebase/quickstart-android/tree/master/mlkit

Answer 1

You created the FirebaseVisionImage from a bitmap. After detection returns, each FirebaseVisionFace describes a bounding box as a Rect that you can use to extract the detected face from the original bitmap, e.g. using Bitmap.createBitmap().