边缘探测

 Color C1, C2, C3, C4;
            int r1, r2, r3, r4,
                g1, g2, g3, g4,
                b1, b2, b3, b4,
                rx, ry, gx, gy, bx, by,
                rr, gg, bb;
            Bitmap bmp = new Bitmap(pictureBox1.Image);
            Bitmap tmp = (Bitmap)bmp.Clone();

            for (int i = 0; i < bmp.Width - 1; i++)
                for (int j = 0; j < bmp.Height - 1; j++)
                {
                    //获得相邻4个像素颜色值
                    ///斜对角
                    C1 = bmp.GetPixel(i, j);
                    C2 = bmp.GetPixel(i + 1, j + 1);
                    C3 = bmp.GetPixel(i + 1, j);
                    C4 = bmp.GetPixel(i, j + 1);
                    //红色分量值
                    r1 = C1.R;
                    r2 = C2.R;
                    r3 = C3.R;
                    r4 = C4.R;
                    rx = r1 - r2;
                    ry = r3 - r4;
                    rr = Math.Abs(rx) + Math.Abs(ry) + 128;
                    //绿色分量值
                    g1 = C1.G;
                    g2 = C2.G;
                    g3 = C3.G;
                    g4 = C4.G;
                    gx = g1 - g2;
                    gy = g3 - g4;
                    gg = Math.Abs(gx) + Math.Abs(gy) + 128;
                    //蓝色分量值
                    b1 = C1.B;
                    b2 = C2.B;
                    b3 = C3.B;
                    b4 = C4.B;
                    bx = b1 - b2;
                    by = b3 - b4;
                    bb = Math.Abs(bx) + Math.Abs(by) + 128;
                    //处理颜色值溢出
                    rr = rr > 255 ? 255 : rr;
                    rr = rr < 0 ? 0 : rr;
                    gg = gg > 255 ? 255 : gg;
                    gg = gg < 0 ? 0 : gg;
                    bb = bb > 255 ? 255 : bb;
                    bb = bb < 0 ? 0 : bb;
                    tmp.SetPixel(i, j, Color.FromArgb(rr, gg, bb));
                }
            pictureBox2.Image = tmp;