Update Headers in PDF documents via .NET SDK

    public static async Task AddImageHeader()
	{
	    const string localPdfDocument = @"C:\Samples\sample.pdf";
	    const string storageFileName = "sample.pdf";
	    const string localImageFile = @"C:\Samples\sample.png";
	    const string storageImageFile = "sample.png";
	    const string localFolder = @"C:\Samples";
	    const string storageTempFolder = "YourTempFolder";
	    const string resultFileName = "output_add_image_header.pdf";
	    const int startPage = 2;
	    const int endPage = 5;
	
	    // Get your AppSid and AppSecret from https://dashboard.aspose.cloud (free registration required). 
	    var pdfApi = new PdfApi(AppSecret, AppSid);
	
	    using var file = File.OpenRead(localPdfDocument);
	    await pdfApi.UploadFileAsync(Path.Combine(storageTempFolder, storageFileName), file);
	
	    using var imageFile = File.OpenRead(localImageFile);
	    await pdfApi.UploadFileAsync(Path.Combine(storageTempFolder, storageImageFile), imageFile);
	
	    ImageHeader header = new ImageHeader(
	        Background: true,
	        HorizontalAlignment: HorizontalAlignment.Center,
	        Opacity: 1,
	        Rotate: Rotation.None,
	        RotateAngle: 0,
	        Zoom: 1,
	        Width: 24,
	        Height: 24,
	        FileName: Path.Combine(storageTempFolder, storageImageFile)
	    );
	
	    var response = await pdfApi.PostDocumentImageHeaderAsync(storageFileName, header, startPage, endPage, folder: storageTempFolder);
	
	    if (response == null)
	        Console.WriteLine("HeadersFootersAddImageHeader(): Unexpected error!");
	    else if (response.Code < 200 || response.Code > 299)
	        Console.WriteLine("HeadersFootersAddImageHeader(): Failed to append image header to the page of document.");
	    else
	    {
	        await (await pdfApi.DownloadFileAsync(Path.Combine(storageTempFolder, storageFileName)))
				.CopyToAsync(File.Create(Path.Combine(localFolder, resultFileName)));

	        Console.WriteLine("HeadersFootersAddImageHeader(): image '{0}' appended as header to the document '{1}.", storageImageFile, resultFileName);
	    }
	}