C# 壓縮圖片 HttpPostedFile轉Image

                #region 以下代碼為保存圖片時，設置壓縮質量
                    Image iSource = Image.FromStream(file.InputStream);//HttpPostedFile轉Image
 　　　　　　　　　　　 long[] qy = new long[1];
                    qy[0] = 10;//設置壓縮的比例1-100
                    ImageFormat tFormat = iSource.RawFormat;
                    int sW = iSource.Width, sH = iSource.Height;
                    Tool tool = new Tool();
                    tool.GetPicZoomSize(ref sW, ref sH, 640, 360);
                    Bitmap filemap = new Bitmap(640, 360);
                    Graphics g = Graphics.FromImage(filemap);
                    g.Clear(Color.WhiteSmoke);
                    g.CompositingQuality = CompositingQuality.HighQuality;
                    g.SmoothingMode = SmoothingMode.HighQuality;
                    g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    g.DrawImage(iSource, new Rectangle((640 - sW) / 2, (360 - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);
                    g.Dispose();
                    //Bitmap filemap = (Bitmap)Image.FromStream(file.InputStream);//HttpPostedFile轉Bitmap
                    EncoderParameters ep = new EncoderParameters();
                    EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
                    ep.Param[0] = eParam;
                    ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                    ImageCodecInfo jpegICIinfo = null;
                    for (int x = 0; x < arrayICI.Length; x++)
                    {
                        if (arrayICI[x].FormatDescription.Equals("JPEG"))
                        {
                            jpegICIinfo = arrayICI[x];
                            break;
                        }
                    }
                    filemap.Save(FilePath + FileName + fileExt, jpegICIinfo, ep);//dFile是壓縮后的新路徑
                    filemap.Dispose();
                    #endregion