System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent);

Graphics g = Graphics.FromImage(img);

 string s = www.itnba.com;

Font f = new Font("黑體",130);

Brush b = new SolidBrush(Color.Red);

g.DrawString(s, f, b, 5, 5);

Bitmap bit = new Bitmap(90, 40);//畫布大小    Graphics g = Graphics.FromImage(bit);//創建繪制對象，告訴它往哪張圖片上繪制    Random r = new Random();    string s = "";    Color color1 = Color.FromArgb(r.Next(155, 255), r.Next(155, 255), r.Next(155, 255));    g.FillRectangle(new SolidBrush(color1), 0, 0, 90, 40);//畫布顏色隨機    for (int i = 0; i < 10; i++)//隨機畫干擾線    {      Color color3 = Color.FromArgb(r.Next(170, 255), r.Next(190, 255), r.Next(170, 255));      Pen pp = new Pen(new SolidBrush(color3), r.Next(0, 5));      g.DrawLine(pp, r.Next(0, 90), r.Next(0, 40), r.Next(0, 90), r.Next(0, 40));    }    string yan = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";//設置隨機的驗證碼，從里面抽取    int wei = 0;    for (int i = 0; i < 4; i++)//取四位驗證碼，顏色隨機    {      string m = yan.Substring(r.Next(0, yan.Length), 1);      s += m;      Color color2 = Color.FromArgb(r.Next(0, 155), r.Next(0, 155), r.Next(0, 155));      int w = r.Next(20, 25);      Font f = new Font("黑體", w);      SolidBrush b = new SolidBrush(color2);      g.DrawString(m, f, b, wei, r.Next(0, 10));      wei += w;    }    Session["YZM"] = s;//把驗證碼保存到session中    for (int i = 0; i < 251; i++)    {      Color color3 = Color.FromArgb(r.Next(0, 255), r.Next(0, 255), r.Next(0, 255));      Pen pp = new Pen(new SolidBrush(color3), r.Next(0, 5));      int a = r.Next(0, 90);      int b = r.Next(0, 40);      g.DrawLine(pp, a, b, (a + 1), (b + 1));    }    bit.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);    Response.End();

<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>    <asp:Image ID="Image1" runat="server" ImageUrl="Default2.aspx" />//這里圖片路徑不是一張圖片的話會默認打開