图片处理算法？！

namespace WindowsApplication29

{

    public partial class Form1 : Form

    {

        Point[] Points = new Point[] { new Point(41, 42), new Point(200, 0), new Point(300, 200), new Point(220, 180), new Point(20, 240),

            new Point(41,42) };



        public Form1()

        {

            InitializeComponent();

            Bitmap bmp = new Bitmap(pictureBox1.Image); // pictureBox1 放的是原图，宽>300，高>220

            pictureBox2.Image = bmp; // 拷贝到pictureBox2先

            GraphicsUnit gu = GraphicsUnit.Pixel; 

            RectangleF r = pictureBox2.Image.GetBounds(ref gu);  

            Region or = new Region(r); // 原始的图片大小的区间

            System.Drawing.Drawing2D.GraphicsPath gp = new System.Drawing.Drawing2D.GraphicsPath();

            gp.AddPolygon(Points);

            Region nr = new Region(gp); // 多边形区间

            or.Exclude(nr); //  原始的图片大小的区间减去多边形区间后的区间

            Graphics g = Graphics.FromImage(pictureBox2.Image);

            g.FillRegion(new SolidBrush(Color.Red), or); // 这个区间涂成红色，也就是你说的图片指定多边形区间外的区间

            g.Dispose();

        }

    }

}