C# 进行图片压缩的示例代码（对jpg压缩效果最好）

直接上代码

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);
   }
 }

调用方法（WPF为例）

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);

}

来源：https://www.cnblogs.com/wdw984/p/13112621.html