How get biggest object from the image and find center pixel of Cropped image

   System.Drawing.Bitmap aq = (Bitmap)pictureBox1.Image;
   Invert a = new Invert();
    aq = a.Apply(aq);
    AForge.Imaging.Image.FormatImage(ref aq);

    /// apply grayscale
    IFilter filter = Grayscale.CommonAlgorithms.BT709;
    aq = filter.Apply(aq);

    Threshold th = new Threshold(220);
    aq = th.Apply(aq);

    ///find the biggest object
    BlobCounter bl = new BlobCounter(aq);
    int i = bl.ObjectsCount;
    ExtractBiggestBlob fil2 = new ExtractBiggestBlob();

    int x = 0;
    int y = 0;
    int h = 0;
    if (i > 0)
    {
        fil2.Apply(aq);
        x = fil2.BlobPosition.X;
        y = fil2.BlobPosition.Y;

        h = fil2.Apply(aq).Height;
    }

    System.Drawing.Bitmap Bitmapsource = (Bitmap)pictureBox1.Image;
    Rectangle section = new Rectangle(new Point(x - h, y - h), new Size(1 * h, 1 * h));

    Bitmap CroppedImage = CropImage(Bitmapsource, section);
    pictureBox2.Image = CroppedImage;
}
    //get crap image


    public Bitmap CropImage(Bitmap source, Rectangle section)  {
    Bitmap bmp = new Bitmap(section.Width, section.Height);
    Graphics g = Graphics.FromImage(bmp);
    g.DrawImage(source, 0, 0, section, GraphicsUnit.Pixel);
    return bmp;}
}