图像压缩

     /**/
        /// <summary>
        /// 保存为JPEG格式，支持压缩质量选项
        /// </summary>
        /// <param name="bmp"></param>
        /// <param name="FileName"></param>
        /// <param name="Qty"></param>
        /// <returns></returns>
        public static bool KiSaveAsJPEG(Bitmap bmp, string FileName, int Qty)
        {
            try
            {
                EncoderParameter p;
                EncoderParameters ps;

                ps = new EncoderParameters(1);

                p = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, Qty);
                ps.Param[0] = p;

                bmp.Save(FileName, GetCodecInfo("image/jpeg"), ps);

                return true;
            }
            catch
            {
                return false;
            }

        }
        /**/
        /// <summary> 
        /// 保存JPG时用 
        /// </summary> 
        /// <param name="mimeType"> </param> 
        /// <returns>得到指定mimeType的ImageCodecInfo </returns> 
        private static ImageCodecInfo GetCodecInfo(string mimeType)
        {
            ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
            foreach (ImageCodecInfo ici in CodecInfo)
            {
                if (ici.MimeType == mimeType) return ici;
            }
            return null;
        }