public static class ImageCompress
    {
        /// <summary>
        /// 图片压缩
        /// </summary>
        /// <param name="imagePath">图片文件路径</param>
        /// <param name="targetFolder">保存文件夹</param>
        /// <param name="quality">压缩质量</param>
        /// <param name="fileSuffix">压缩后的文件名后缀（防止直接覆盖原文件）</param>
        public static void CompressionImage(string imagePath, string targetFolder, long quality = 100, string fileSuffix = "compress")
        {
            if (!File.Exists(imagePath))
            {
                throw new FileNotFoundException();
            }
            if (!Directory.Exists(targetFolder))
            {
                Directory.CreateDirectory(targetFolder);
            }
            var fileInfo = new FileInfo(imagePath);
            var fileName = fileInfo.Name.Replace(fileInfo.Extension, "");
            var fileFullName = Path.Combine($"{targetFolder}", $"{fileName}_{fileSuffix}{fileInfo.Extension}");

            var imageByte = CompressionImage(imagePath, quality);
            var ms = new MemoryStream(imageByte);
            var image = Image.FromStream(ms);
            image.Save(fileFullName);
            ms.Close();
            ms.Dispose();
            image.Dispose();
        }
        private static byte[] CompressionImage(string imagePath, long quality)
        {
            using (var fileStream = new FileStream(imagePath, FileMode.Open))
            {
                using (var img =Image.FromStream(fileStream))
                {
                    using (var bitmap = new Bitmap(img))
                    {
                        var codecInfo = GetEncoder(img.RawFormat);
                        var myEncoder = Encoder.Quality;
                        var myEncoderParameters = new EncoderParameters(1);
                        var myEncoderParameter = new EncoderParameter(myEncoder, quality);
                        myEncoderParameters.Param[0] = myEncoderParameter;
                        using (var ms = new MemoryStream())
                        {
                            bitmap.Save(ms, codecInfo, myEncoderParameters);
                            myEncoderParameters.Dispose();
                            myEncoderParameter.Dispose();
                            return ms.ToArray();
                        }
                    }
                }
            }
        }

        private static ImageCodecInfo GetEncoder(ImageFormat format)
        {
            var codecs = ImageCodecInfo.GetImageDecoders();
            return codecs.FirstOrDefault(codec => codec.FormatID == format.Guid);
        }
    }

private void Button_Click(object sender, RoutedEventArgs e)
        {
            var fileDialog = new OpenFileDialog();
            var fileSelect = "";
            if (fileDialog.ShowDialog(this)==true)
            {
                fileSelect = fileDialog.FileName;
            }
            if(string.IsNullOrWhiteSpace(fileSelect)) return;
            
            ImageCompress.CompressionImage(fileSelect,@"d:\",50);

        }