Bitmap jpg = (Bitmap)pictureBox2.Image, jpg1 = new Bitmap(jpg.Width, jpg.Height);
            int x, y, r, g, b; Color cl; double rs, gs, bs;
            double[,] w = new double[3, 3]
                {
                    {-1,-1,-1 },
                    {-1,9,-1 },
                    {-1,-1,-1 }
                };

            for (y = 1; y < jpg.Height - 1; y++)
            {
                for (x = 1; x < jpg.Width - 1; x++)
                {
                    rs = gs = bs = 0;
                    for (int i = -1; i <= 1; i++)
                        for (int j = -1; j <= 1; j++)
                        {
                            cl = jpg.GetPixel(x + i, y + j);
                            rs += cl.R * w[i + 1, j + 1]; gs += cl.G * w[i + 1, j + 1]; bs += cl.B * w[i + 1, j + 1];

                            r = Convert.ToInt32(rs);
                            g = Convert.ToInt32(gs);
                            b = Convert.ToInt32(bs);
                            if (r < 0) r = 0; else if (r > 255) r = 255;
                            if (g < 0) g = 0; else if (g > 255) g = 255;
                            if (b < 0) b = 0; else if (b > 255) b = 255;
                            cl = Color.FromArgb(r, g, b);
                            jpg1.SetPixel(x, y, cl);
                        }
                    Application.DoEvents();
                }
                pictureBox3.Image = jpg1;
            }
        }