C# 如何進行圖像的壓縮

從網上找的很是有效。圖片3M到500k

   private static ImageCodecInfo GetEncoderInfo(String mimeType)
        {
            int j;
            ImageCodecInfo[] encoders;
            encoders = ImageCodecInfo.GetImageEncoders();
            for (j = 0; j < encoders.Length; ++j)
            {
                if (encoders[j].MimeType == mimeType)
                    return encoders[j];
            }
            return null;
        }

        /// <summary>
        /// 圖片壓縮(下降質量以減少文件的大小)
        /// </summary>
        /// <param name="srcBitmap">傳入的Bitmap對象</param>
        /// <param name="destStream">壓縮後的Stream對象</param>
        /// <param name="level">壓縮等級，0到100，0 最差質量，100 最佳</param>
        public static void Compress(Bitmap srcBitmap, Stream destStream, long level)
        {
            ImageCodecInfo myImageCodecInfo;
            Encoder myEncoder;
            EncoderParameter myEncoderParameter;
            EncoderParameters myEncoderParameters;

            // Get an ImageCodecInfo object that represents the JPEG codec.
            myImageCodecInfo = GetEncoderInfo("image/jpeg");

            // Create an Encoder object based on the GUID

            // for the Quality parameter category.
            myEncoder = Encoder.Quality;

            // Create an EncoderParameters object.
            // An EncoderParameters object has an array of EncoderParameter
            // objects. In this case, there is only one

            // EncoderParameter object in the array.
            myEncoderParameters = new EncoderParameters(1);

            // Save the bitmap as a JPEG file with 給定的 quality level
            myEncoderParameter = new EncoderParameter(myEncoder, level);
            myEncoderParameters.Param[0] = myEncoderParameter;
            srcBitmap.Save(destStream, myImageCodecInfo, myEncoderParameters);
        }

        /// <summary>
        /// 圖片壓縮(下降質量以減少文件的大小)
        /// </summary>
        /// <param name="srcBitMap">傳入的Bitmap對象</param>
        /// <param name="destFile">壓縮後的圖片保存路徑</param>
        /// <param name="level">壓縮等級，0到100，0 最差質量，100 最佳</param>
        public static void Compress(Bitmap srcBitMap, string destFile, long level)
        {
            Stream s = new FileStream(destFile, FileMode.Create);
            Compress(srcBitMap, s, level);
            s.Close();
        }