C# 产生验证码图片

一、实例并初始化GDI+ 位图

       Bitmap image = new Bitmap(int width，int height);

二、实例并初始化绘图画面对象

      Graphics g = Graphics.FromImage(image);

     1.  清空并已指定的颜色填充背景

             g.Clear(Color.White);

     2. 画图片的背景噪音线

             Point Point_1 = new Point(random.Next(image.Width), random.Next(image.Height)); 

             Point Point_2 = new Point(random.Next(image.Width), random.Next(image.Height)); 

             g.DrawLine(new Pen(Color.Black), Point_1, Point_2);

     3.画图片的前景噪音点
             Point point = new Point(random.Next(image.Width),random.Next(image.Height));
             image.SetPixel(tem_point.X,tem_point.Y, Color.FromArgb(random.Next()));

    4.画边框

             g.DrawRectangle(new Pen(Color.Red), 0, 0, image.Width - 1, image.Height - 1);

    5.画字符串

             Font font = new Font("宋体", 12, (FontStyle.Bold));
             LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),    Color.Blue, Color.Red, 1.2f, true);
             g.DrawString(txt, font, brush, 2, 2);

C# 产生验证码图片

原文：http://blog.csdn.net/ilipan/article/details/45370021