c# bitmap压缩

 public 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;
        }
        public static void savePath(Bitmap bmp, string str)//保存路径
        {
            ImageCodecInfo myImageCodecInfo;
            System.Drawing.Imaging.Encoder myEncoder;
            EncoderParameter myEncoderParameter;
            EncoderParameters myEncoderParameters;

            myImageCodecInfo = GetEncoderInfo("image/jpeg");
            myEncoder = System.Drawing.Imaging.Encoder.Quality;
            myEncoderParameters = new EncoderParameters(1);
            myEncoderParameter = new EncoderParameter(myEncoder, 80L);
            myEncoderParameters.Param[0] = myEncoderParameter;
            bmp.Save(str, myImageCodecInfo, myEncoderParameters); 
        }

只需要传入Bitmap和路径，别的不需要修改.80L代表保存质量，还可以设置50L，25L，质量更差。