public static Bitmap toOvalBitmap(@NonNull Bitmap bitmap) {
    int width = bitmap.getWidth();
    int height = bitmap.getHeight();
    Bitmap output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

    Canvas canvas = new Canvas(output);

    int color = 0xff424242;
    Paint paint = new Paint();

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);

    RectF rect = new RectF(0, 0, width, height);
    canvas.drawOval(rect, paint);
    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(bitmap, 0, 0, paint);

    bitmap.recycle();

    return output;
  }
Create a new bitmap that has all pixels beyond the oval shape transparent. Old bitmap is
recycled.
core/src/main/java/com/theartofdev/edmodo/cropper/CropImage.java