C#图片压缩

        #region getThumImage
        /**/
        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="sourceFile">原始图片文件</param>
        /// <param name="quality">质量压缩比</param>
        /// <param name="multiple">收缩倍数</param>
        /// <param name="outputFile">输出文件名</param>
        /// <returns>成功返回true,失败则返回false</returns>
        public static bool getThumImage(String sourceFile, long quality, int multiple, String outputFile)
        {
            try
            {
                long imageQuality = quality;
                Bitmap sourceImage = new Bitmap(sourceFile);
                //ImageCodecInfo myImageCodecInfo = GetEncoderInfo("image/jpeg");
                ImageCodecInfo myImageCodecInfo = GetEncoderInfo("image/png");

                ImageCodecInfo saveImageCodeInfo = GetEncoderInfo("image/jpeg");

                System.Drawing.Imaging.Encoder myEncoder = System.Drawing.Imaging.Encoder.Quality;
                EncoderParameters myEncoderParameters = new EncoderParameters(1);
                EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, imageQuality);
                myEncoderParameters.Param[0] = myEncoderParameter;
                float xWidth = sourceImage.Width;
                float yWidth = sourceImage.Height;
                Bitmap newImage = new Bitmap((int)(xWidth / multiple), (int)(yWidth / multiple));
                Graphics g = Graphics.FromImage(newImage);
                g.DrawImage(sourceImage, 0, 0, xWidth / multiple, yWidth / multiple);
                g.Dispose();
                //newImage.Save(outputFile, myImageCodecInfo, myEncoderParameters);
                //按照jpg的格式保存
                newImage.Save(outputFile, saveImageCodeInfo, myEncoderParameters);
                return true;
            }
            catch
            {
                return false;
            }
        }
        #endregion getThumImage


        /**/
        /// <summary>
        /// 获取图片编码信息
        /// </summary>
        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;
        }

需要引用以下命名空间

using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;

调用方式：

<pre name="code" class="csharp">            string pathPerc = @"F:\cc.jpg";
            string source = @"D:\1443410994498-.PNG";  //原图片地址
            if (!File.Exists(pathPerc))
            {
                File.Create(pathPerc).Close();
            }
            else
            {
                File.Delete(pathPerc);
                File.Create(pathPerc).Close();
            }
            bool result = Common.getThumImage(source, 20, 1, pathPerc);

            if (result)
            {
                Console.WriteLine("压缩成功");
                Console.ReadKey();
            }
            else
            {
                Console.WriteLine("压缩失败");
                Console.ReadKey();
            }