关于asp。net GDI+图片的等比例缩放

我需要做一个功能，就是在后台上传一张图片，用gdi+把他等比例缩放成一张大图和一张小图保存到数据库方便调用可是我在网上找的代码都会报同一个错误 gdi+ 中发生一般性错误也不知道到时是什么错误网上找的代码看得也不太懂，求高人指点！代码执行到最后一行出错
/// <SUMMARY>
        /// 图片缩放
        /// </SUMMARY>
        /// <PARAM name="sourceFile">图片源路径</PARAM>
        /// <PARAM name="destFile">缩放后图片输出路径</PARAM>
        /// <PARAM name="destHeight">缩放后图片高度</PARAM>
        /// <PARAM name="destWidth">缩放后图片宽度</PARAM>
        /// <RETURNS></RETURNS>
        public static bool GetThumbnail(string sourceFile, string destFile, int destHeight, int destWidth)
        {
            System.Drawing.Image imgSource = System.Drawing.Image.FromFile(sourceFile);
            System.Drawing.Imaging.ImageFormat thisFormat = imgSource.RawFormat;
            int sW = 0, sH = 0;
            // 按比例缩放
            int sWidth = imgSource.Width;
            int sHeight = imgSource.Height;

            if (sHeight > destHeight || sWidth > destWidth)
            {
                if ((sWidth * destHeight) > (sHeight * destWidth))
                {
                    sW = destWidth;
                    sH = (destWidth * sHeight) / sWidth;
                }
                else
                {
                    sH = destHeight;
                    sW = (sWidth * destHeight) / sHeight;
                }
            }
            else
            {
                sW = sWidth;
                sH = sHeight;
            }

            Bitmap outBmp = new Bitmap(destWidth, destHeight);
            Graphics g = Graphics.FromImage(outBmp);
            g.Clear(Color.WhiteSmoke);

            // 设置画布的描绘质量
            g.CompositingQuality = CompositingQuality.HighQuality;
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;

            g.DrawImage(imgSource, new Rectangle((destWidth - sW) / 2, (destHeight - sH) / 2, sW, sH), 0, 0, imgSource.Width, imgSource.Height, GraphicsUnit.Pixel);
            g.Dispose();

            // 以下代码为保存图片时，设置压缩质量
            EncoderParameters encoderParams = new EncoderParameters();
            long[] quality = new long[1];
            quality[0] = 100;

            EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
            encoderParams.Param[0] = encoderParam;

            try
            {
                //获得包含有关内置图像编码解码器的信息的ImageCodecInfo 对象。
                ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo jpegICI = null;
                for (int x = 0; x < arrayICI.Length; x++)
                {
                    if (arrayICI[x].FormatDescription.Equals("JPEG"))
                    {
                        jpegICI = arrayICI[x];//设置JPEG编码
                        break;
                    }
                }

                if (jpegICI != null)
                {
                    outBmp.Save(destFile, jpegICI, encoderParams);
                }
                else
                {
                    outBmp.Save(destFile, thisFormat);
                }

                return true;
            }
            catch
            {
                return false;
            }
            finally
            {
                imgSource.Dispose();
                outBmp.Dispose();
            }

        }

补充：.NET技术 ,  ASP.NET