How to set GdPicture OCR as the default OCR engine?

There are two methods to configure GdPicture OCR as the default OCR engine:

1. Modify the Web Service configuration:

   <!-- The default OCR engine to use. For a list of available OCR engines, see
   the <ocrProcessors> section below. This may require third-party software. -->
   <add key="OCR.Default" value="GdPictureOCR"/>

2. Specify the desired OCR engine directly in the code:

   static void Main(string[] args)
   {
       DocumentConverterServiceClient client = null;
   
       try
       {
           // ** Delete any processed files from a previous run.
           foreach (FileInfo f in new DirectoryInfo(".").GetFiles("*_ocr.pdf"))
               f.Delete();
   
           // ** Determine the source file and read it into a byte array.
           string sourceFileName = null;
           if (args.Length == 0)
           {
               // ** If nothing is specified, then read the first PDF file from the current folder.
               string[] sourceFiles = Directory.GetFiles(Directory.GetCurrentDirectory(), "*.pdf");
               if (sourceFiles.Length > 0)
                   sourceFileName = sourceFiles[0];
               else
               {
                   Console.WriteLine("Please specify a document to OCR.");
                   Console.ReadKey();
                   return;
               }
           }
           else
               sourceFileName = args[0];
   
           byte[] sourceFile = File.ReadAllBytes(sourceFileName);
   
           // ** Open the service and configure the bindings.
           client = OpenService(SERVICE_URL);
   
           //** Set the absolute minimum open options.
           OpenOptions openOptions = new OpenOptions();
           openOptions.OriginalFileName = Path.GetFileName(sourceFileName);
           openOptions.FileExtension = Path.GetExtension(sourceFileName);
   
           // ** Set the absolute minimum conversion settings.
           ConversionSettings conversionSettings = new ConversionSettings();
   
           // ** OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR
           OCRSettings ocr = new OCRSettings();
           ocr.Language = OCRLanguage.English.ToString();
           ocr.OCREngine = "GdPictureOCR";
           conversionSettings.OCRSettings = ocr;
           // ** OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR OCR
   
           // ** Carry out the conversion.
           Console.WriteLine("Processing file " + sourceFileName + ".");
           byte[] convFile = client.ProcessChanges(sourceFile, openOptions, conversionSettings);
   
           // ** Write the processed file back to the file system with a PDF extension.
           string destinationFileName = Path.GetFileNameWithoutExtension(sourceFileName) + "_ocr.pdf";
           using (FileStream fs = File.Create(destinationFileName))
           {
               fs.Write(convFile, 0, convFile.Length);
               fs.Close();
           }
   
           Console.WriteLine("File written to " + destinationFileName);
   
           // ** Open the generated PDF file in a PDF reader.
           Console.WriteLine("Launching file in PDF Reader");
           Process.Start(destinationFileName);
       }
       catch (FaultException<WebServiceFaultException> ex)
       {
           Console.WriteLine("FaultException occurred: ExceptionType: " +
                               ex.Detail.ExceptionType.ToString());
       }
       catch (Exception ex)
       {
           Console.WriteLine(ex.ToString());
       }
       finally
       {
           CloseService(client);
       }
       Console.ReadKey();
   }
   
   /// <summary>
   /// Configure the bindings and endpoints and open the service using the specified address.
   /// </summary>
   /// <returns>An instance of the Web Service.</returns>
   public static DocumentConverterServiceClient OpenService(string address)
   {
       DocumentConverterServiceClient client = null;
   
       try
       {
           BasicHttpBinding binding = new BasicHttpBinding();
           // ** Use standard Windows Security.
           binding.Security.Mode = BasicHttpSecurityMode.TransportCredentialOnly;
           binding.Security.Transport.ClientCredentialType =
                                                           HttpClientCredentialType.Windows;
           // ** Increase the client timeout to deal with (very) long running requests.
           binding.SendTimeout = TimeSpan.FromMinutes(120);
           binding.ReceiveTimeout = TimeSpan.FromMinutes(120);
           // ** Set the maximum document size to 50MB
           binding.MaxReceivedMessageSize = 50 * 1024 * 1024;
           binding.ReaderQuotas.MaxArrayLength = 50 * 1024 * 1024;
           binding.ReaderQuotas.MaxStringContentLength = 50 * 1024 * 1024;
   
           // ** Specify an identity (or any identity) to get past .net3.5 sp1.
           EndpointIdentity epi = EndpointIdentity.CreateUpnIdentity("unknown");
           EndpointAddress epa = new EndpointAddress(new Uri(address), epi);
   
           client = new DocumentConverterServiceClient(binding, epa);
   
           client.Open();
   
           return client;
       }
       catch (Exception)
       {
           CloseService(client);
           throw;
       }
   }
   
   /// <summary>
   /// Check if the client is open and then close it.
   /// </summary>
   /// <param name="client">The client to close</param>
   public static void CloseService(DocumentConverterServiceClient client)
   {
       if (client != null && client.State == CommunicationState.Opened)
           client.Close();
   }