/// <summary>
        /// 按指定的壓縮質量及格式保存圖片（微軟的Image.Save方法保存到圖片壓縮質量為75)
        /// </summary>
        /// <param name="sourceImage">要保存的圖片的Image對象</param>
        /// <param name="savePath">圖片要保存的絕對路徑</param>
        /// <param name="imageQualityValue">圖片要保存的壓縮質量，該參數的值為1至100的整數，數值越大，保存質量越好</param>
        /// <returns>保存成功，返回true；反之，返回false</returns>
        public bool SaveImageForSpecifiedQuality(System.Drawing.Image sourceImage, string savePath, int imageQualityValue)
        {
            //以下代碼為保存圖片時，設置壓縮質量
            EncoderParameters encoderParameters = new EncoderParameters();
            EncoderParameter encoderParameter = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, imageQualityValue);
            encoderParameters.Param[0] = encoderParameter;
            try
            {
                ImageCodecInfo[] ImageCodecInfoArray = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo jpegImageCodecInfo = null;
                for (int i = 0; i < ImageCodecInfoArray.Length; i++)
                {
                    if (ImageCodecInfoArray[i].FormatDescription.Equals("JPEG"))
                    {
                        jpegImageCodecInfo = ImageCodecInfoArray[i];
                        break;
                    }
                }   
                sourceImage.Save(savePath, jpegImageCodecInfo, encoderParameters);              
                return true;
            }
            catch
            {
                return false;
            }
        }

System.Drawing.Image image = System.Drawing.Image.FromFile("D:\\TestImage\\0.jpg");
SaveImageForSpecifiedQuality(image, "D:\\TestImage\\1.jpg", 100, ImageFormat.Jpeg);image.Dispose();