Android: Check Number of Faces Before Crop Image in Android

Question

currently I am developing android application. In my application I need to crop image from gallery. However, before I allow the user to crop the image, I want to check whether there is face detected in the image or not.

Here is how I allow user to crop an image from gallery:

 Intent pickImageIntent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

    pickImageIntent.setType("image/*");
    pickImageIntent.putExtra("crop", "true");
    pickImageIntent.putExtra("noFaceDetection", true); 
    pickImageIntent.putExtra("aspectX", size);
    pickImageIntent.putExtra("aspectY", size);
    pickImageIntent.putExtra("outputX", size);
    pickImageIntent.putExtra("outputY", size);
    pickImageIntent.putExtra("scale", true);
    pickImageIntent.putExtra(MediaStore.EXTRA_OUTPUT, getImageUri());
    pickImageIntent.putExtra("outputFormat", Bitmap.CompressFormat.JPEG.toString());
    startActivityForResult(pickImageIntent, RESULT_LOAD_IMAGE);

Before I run above code, I want to do something like this:

imageWidth = myBitmap.getWidth();
   imageHeight = myBitmap.getHeight();
   myFace = new FaceDetector.Face[numberOfFace];
   myFaceDetect = new FaceDetector(imageWidth, imageHeight,
     numberOfFace);
   numberOfFaceDetected = myFaceDetect.findFaces(myBitmap, myFace);

But I am confuse about how to do it. Anyone can help me? Thanks.