如何使用c＃压缩输入流？

Question

我使用c＃web api为图像上传编写了代码。现在我想在服务器上完成图像上传。这件事也完成了。但我想在服务器上传之后压缩图像。但我怎么能不知道任何人知道怎么办呢，请告诉我。我想压缩图像，然后使用webapi上传到amzon s3服务器上。

这是我的代码=＆gt;

 [HttpPost]
[Route("FileUpload")]
public HttpResponseMessage FileUpload()
{
    try
    {               
        var httpRequest = HttpContext.Current.Request;
        if (httpRequest.Files.Count > 0)
        {
            foreach (string file in httpRequest.Files)
            {
                var postedFile = httpRequest.Files[file];
                string fname = System.IO.Path.GetFileNameWithoutExtension(postedFile.FileName.ToString());
                string extension = Path.GetExtension(postedFile.FileName);
                Image img = null;
                string newFileName = "";
                string path = "";
               img = Image.FromStream(postedFile.InputStream);
                string path = ConfigurationManager.AppSettings["ImageUploadPath"].ToString();
                newFileName = DateTime.Now.ToString("yyyyMMddhhmmssfff") + ".jpeg";
                string filePath = Path.Combine(path, newFileName);

                UploadImageOnServer(postedFile.InputStream,path + newFileName);
               } 
        }            
    }
    catch (Exception ex)
    {
    }            
    return Request.CreateResponse(HttpStatusCode.OK, "Done");
}

这是我的上传代码服务器=＆gt;

 public static void UploadImageOnServer(Stream File, string Key)
 {
  var client = new AmazonS3Client(Amazon.RegionEndpoint.USEast1);

    PutObjectRequest putRequest = new PutObjectRequest
    {
        BucketName = Bucketname,
        InputStream = File,
        CannedACL = S3CannedACL.PublicRead,
        Key = Key
    };
    PutObjectResponse response = client.PutObject(putRequest);
 }

这是我现在的代码，我想压缩图像。请任何人知道，请告诉我。