C# 彩色变黑白（灰度图像）

//彩色转黑白 灰度图像
 

       private void button11_Click(object sender, EventArgs e)
        {
            Color c = new Color();
            Bitmap b = new Bitmap(pictureBox6.Image);
            Bitmap b1 = new Bitmap(pictureBox6.Image);
            int rr, gg, bb, cc;
            for (int i = 0; i < b.Width; i++)
            {
                for (int j = 0; j < b.Height; j++)
                {
                    c = b.GetPixel(i, j);
                    rr = c.R;
                    gg = c.G;
                    bb = c.B;
                    cc = (int)((rr + gg + bb) / 3);
                    if (cc < 0)
                        cc = 0;
                    if (cc > 255)
                        cc = 255;
                    //用FromArgb把整形转换成颜色值
                    Color c1 = Color.FromArgb(cc, cc, cc);
                    b1.SetPixel(i, j, c1);
                }
                pictureBox7.Refresh();
                pictureBox7.Image = b1;
            }
        }