已经调试通过
pic.aspx
<%@ Page language="c#" Codebehind="pic.aspx.cs" AutoEventWireup="false" Inherits="TestWeb.pic" %>


 
  
  
  
  
  http://schemas.microsoft.com/intellisense/ie5">
 
 
  

   

给图片加上水印效果(调试通过)

   加在图片上的文字：
   

   
   

   
  

 

-----------------------------------------------------------------------
pic.aspx.cs
using System;
using System.IO;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System.Drawing.Design;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;namespace TestWeb
{
 ///

 /// pic 的摘要说明。
 ///

 public class pic : System.Web.UI.Page
 {
  protected System.Web.UI.WebControls.Button _save;
  protected System.Web.UI.HtmlControls.HtmlInputText AddText;
  protected System.Web.UI.WebControls.Label _dd;
  protected System.Web.UI.HtmlControls.HtmlInputFile UploadFile;
 
  private void Page_Load(object sender, System.EventArgs e)
  {
   // 在此处放置用户代码以初始化页面
  }  #region Web 窗体设计器生成的代码
  override protected void OnInit(EventArgs e)
  {
   //
   // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
   //
   InitializeComponent();
   base.OnInit(e);
  }
  
  ///

  /// 设计器支持所需的方法 - 不要使用代码编辑器修改
  /// 此方法的内容。
  ///

  private void InitializeComponent()
  {   
   this._save.Click += new System.EventHandler(this._save_Click);
   this.Load += new System.EventHandler(this.Page_Load);  }
  #endregion  private void _save_Click(object sender, System.EventArgs e)
  {
   if(UploadFile.PostedFile.FileName.Trim()!="")
   {
    //上传文件
    string extension = Path.GetExtension(UploadFile.PostedFile.FileName).ToUpper();
    string fileName = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString();
    string path = Server.MapPath(".") + "/UploadFile/" + fileName + extension;
    UploadFile.PostedFile.SaveAs(path);    
    //加文字水印，注意，这里的代码和以下加图片水印的代码不能共存
    System.Drawing.Image image = System.Drawing.Image.FromFile(path);
    Graphics g = Graphics.FromImage(image);
    g.DrawImage(image, 0, 0, image.Width, image.Height);
    Font f = new Font("Verdana", 9);
    Brush b = new SolidBrush(Color.White);
    string addText = this.AddText.Value.Trim();
    //g.DrawString(addText, f, b, 10, 10);
    g.DrawString(addText, f, b, 0, 0);
    g.Dispose();
    //    //加图片水印,aa.gif是加盖的图
//    System.Drawing.Image image = System.Drawing.Image.FromFile(path);
//    System.Drawing.Image copyImage = System.Drawing.Image.FromFile( Server.MapPath(".") + "/aa.gif");
//    Graphics g = Graphics.FromImage(image);
//    g.DrawImage(copyImage, new Rectangle(image.Width-copyImage.Width, image.Height-copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);
//    g.Dispose();    //保存加水印过后的图片,删除原始图片
    string newPath = Server.MapPath(".") + "/UploadFile/" + fileName + "_new" + extension;
    image.Save(newPath);
    image.Dispose();
    if(File.Exists(path))
    {
     File.Delete(path);
    }    Response.Redirect(newPath);
   }
  }
 }
}