修改指定图片的分辨率

 #region 修改指定图片的分辨率
        /// <summary>  
        /// 修改指定图片的分辨率  
        /// </summary>  
        /// <param name="fileFoldUrl">文件夹url</param>  
        /// <param name="fileName">文件名</param>  
        /// <param name="filePath">文件路径，带文件名</param>  
        /// <param name="_width">分辨率的宽</param>  
        /// <param name="_height">分辨率的高</param>  
        public static void update_picture(string fileFoldUrl, string fileName, string filePath, int _width, int _height)
        {
            try
            {
                byte[] zp = load_pictMemory(filePath);

                MemoryStream ms = new MemoryStream(zp);

                System.Drawing.Image img = System.Drawing.Image.FromStream(ms);

                Bitmap btp = new Bitmap(img, _width, _height);

                DirectoryInfo dti = new DirectoryInfo(fileFoldUrl);

                FileInfo[] fis = dti.GetFiles();

                string fileUrl = fileFoldUrl + fileName;

                btp.Save(fileUrl);
            }
            catch (Exception)
            {
                throw;
            }
        }

        /// <summary>  
        /// 获取指定文件流的字节大小  
        /// </summary>  
        /// <param name="filePath">文件路径</param>  
        /// <returns>byte[]</returns>  
        public static byte[] load_pictMemory(string filePath)
        {
            byte[] pictData = null;

            FileInfo fi = new FileInfo(filePath);

            if (fi.Exists)
            {
                pictData = new byte[fi.Length];

                FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite);

                BinaryReader br = new BinaryReader(fs);

                br.Read(pictData, 0, Convert.ToInt32(fi.Length));

                fs.Dispose();
            }
            else
            {
                HttpContext.Current.Response.Write("<script language='javascript'>alert('没有找到你所指定的图片')</script>");
            }
            return pictData;
        }
        #endregion