Controller:

        public ActionResult Upload()
        {
            return View();
        }
        [HttpPost]
        public ActionResult Upload(HttpPostedFileBase file)
        {
            var ostream = file.InputStream;
            var orp_w_picpath = Image.FromStream(ostream);
            int owidth = orp_w_picpath.Width;  //原图宽度 
            int oheight = orp_w_picpath.Height;  //原图高度
            int objwidth = 100;   //设置缩略图初始宽度 
            int objheight = 100;  //设置缩略图初始高度
            //按比例计算出缩略图的宽度和高度 
            if (owidth >= oheight)
            {
                objheight = (int)Math.Floor(Convert.ToDouble(oheight) * (Convert.ToDouble(objwidth) / Convert.ToDouble(owidth)));
            }
            else
            {
                objwidth = (int)Math.Floor(Convert.ToDouble(owidth) * (Convert.ToDouble(objheight) / Convert.ToDouble(oheight)));
            }
            Bitmap objp_w_picpath = new Bitmap(objwidth, objheight);
            Graphics graphics = Graphics.FromImage(objp_w_picpath);
            graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量插值法 
            graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置高质量,低速度呈现平滑程度 
            graphics.Clear(Color.Transparent); //清空画布并以透明背景色填充 
            graphics.DrawImage(orp_w_picpath, new Rectangle(0, 0, objwidth, objheight), new Rectangle(0, 0, owidth, oheight), GraphicsUnit.Pixel);
 
            //rewrite p_w_picpathname
            var extensionName = Path.GetExtension(file.FileName);
            var oriname = "ori" + DateTime.Now.ToString("yyyyMMddHHmmss") + extensionName;
            var objname = "obj" + DateTime.Now.ToString("yyyyMMddHHmmss") + ".png";
 
            var orifilePath = Path.Combine(HttpContext.Server.MapPath("/content/videos"), Path.GetFileName(oriname));
            var objfilePath = Path.Combine(HttpContext.Server.MapPath("/content/videos"), Path.GetFileName(objname));
            try
            {
                file.SaveAs(orifilePath);
                objp_w_picpath.Save(objfilePath, System.Drawing.Imaging.ImageFormat.Png);
            }
 
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                //释放资源 
                orp_w_picpath.Dispose();
                graphics.Dispose();
                objp_w_picpath.Dispose();
            }
 
            return RedirectToAction("Index");
        }
 
View:
@using (Html.BeginForm("Upload", "Admin", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
    <label>
    Filename:</label>
    <input type="file" name="file" />
    <input type="submit" value="Submit" />
}