using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Imaging;

namespace WebTest
{
    public partial class WebForm5 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Bitmap img = new Bitmap(@"E:\Temp\psu (1).jpg");
            SolidBrush pixelBrush;
            Graphics g = Graphics.FromImage(img);
            for (int i = 0; i < img.Width; i++)
            {
            
                for (int j = 0; j < img.Height; j++)
                {

                    Color pixelColor = img.GetPixel(i-i%2, j-j%2);
       
                     pixelBrush = new SolidBrush(pixelColor);
                    g.FillRectangle(pixelBrush, i, j, 1, 1); 
                   
                }
    
               
            }


            Response.ContentType = "image/JPEG";
            img.Save(Response.OutputStream, ImageFormat.Jpeg);
            Response.End();
        }
    }
}

------解决方案--------------------
所有圖像控件都有這小兒科功能