图片噪点的产生
 
public Bitmap CreateBitmap()

{

Response.ContentType="image/jpeg";

Bitmap bitmap=new Bitmap(100,30);

Graphics graphics =Graphics.FromImage(bitmap);

Random random =new Random();

for(int i =0;i<30;i++)

{

int x1 = random.Next(100);

int x2 =random.Next(100);

int y1 =random.Next(30);

int y2 = random.Next(30);

graphics.DrawLine(new Pen(Color.Black,1), new Point(x1,y1),new Point(x2,y2));

}

return bitmap;

}

调用段:

Bitmap  bitmap= CreateBitmap();

bitmap.Save(Response.OutputStream,ImageFormat.Jpeg);