Image processing , c#

private void check_Click(object sender, EventArgs e)
        {
            // locate objects using blob counter
            BlobCounter blobCounter = new BlobCounter();
            blobCounter.ProcessImage((Bitmap)PictureBox1.Image);
            Blob[] blobs = blobCounter.GetObjectsInformation();
            // create Graphics object to draw on the image and a pen
            Graphics g = Graphics.FromImage((Bitmap)TargetPic.Image);
            Pen redPen = new Pen(Color.Red, 2);
            // check each object and draw circle around objects, which
            // are recognized as circles
            for (int i = 0, n = blobs.Length; i < n; i++)
            {
                List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blob[i]);

                AForge.Point center;
                float radius;

                if (shapeChecker.IsCircle(edgePoints, out center, out radius))
                {
                    g.DrawEllipse(redPen,
                        (int)(center.X - radius),
                        (int)(center.Y - radius),
                        (int)(radius * 2),
                        (int)(radius * 2));
                }
            }

            redPen.Dispose();
            g.Dispose();
        }