LEADTOOLS OCR (Leadtools.Forms.Ocr assembly)
LEAD Technologies, Inc

RunJob Method

Example 





The IOcrAutoRecognizeJob to run this parameter cannot be null (Nothing in Visual Basic). Use CreateJob to create a job.
Runs a job .NET support
Syntax
'Declaration
 
Function RunJob( _
   ByVal job As IOcrAutoRecognizeJob _
) As OcrAutoRecognizeManagerJobStatus
'Usage
 
Dim instance As IOcrAutoRecognizeManager
Dim job As IOcrAutoRecognizeJob
Dim value As OcrAutoRecognizeManagerJobStatus
 
value = instance.RunJob(job)
function Leadtools.Forms.Ocr.IOcrAutoRecognizeManager.RunJob( 
   job 
)

Parameters

job
The IOcrAutoRecognizeJob to run this parameter cannot be null (Nothing in Visual Basic). Use CreateJob to create a job.

Return Value

An OcrAutoRecognizeManagerJobStatus enumeration member that determines whether the job was completed successfully or aborted due to errors or user action.
Remarks

If you call this method from the same thread that created IOcrAutoRecognizeManager, then the current thread will block till this method returns. To run a job asynchronously, use RunJobAsync.

When this method returns, the IOcrAutoRecognizeJob.Errors member of job will contain any errors that might have occurred during the recognition process.

To use this method, initialize a new OcrAutoRecognizeJobData object with the job's parameters (input image file name, pages, output document format, output document name, optional zones file name, etc.), then use CreateJob to create the IOcrAutoRecognizeJob object passed as job to this method. Finally, call RunJob passing the IOcrAutoRecognizeJob object.

This method will perform the following operations:

  1. The JobStarted event is triggered.

  2. Creates one ore more IOcrDocument object to store the pages into. The number of OCR documents created is dependant on MaximumThreadsPerJob. If this value is 0 (maximum CPUs/cores) or is greater than 1 and multiple threads is supported by this engine, then more than one document might be created to participate in the recognition process.

  3. Loops through the pages specified in OcrAutoRecognizeJobData.FirstPageNumber and in OcrAutoRecognizeJobData.LastPageNumber in OcrAutoRecognizeJobData.ImageFileName and for each page:

    The page is added to its document using IOcrPageCollection.AddPage.

    If OcrAutoRecognizeJobData.ZonesFileName contains a valid multi-page zone file name and has an entry for the current page, then the zones are loaded with IOcrPage.LoadZones(fileName, pageNumber) and applied to the page. If OcrAutoRecognizeJobData.ZonesFileName is a null (Nothing in Visual Basic) reference or it does not contain an equivalant page number, auto-decomposing of the page is performed instead with IOcrPage.AutoZone. A valid multi-page zone file that has entries for all document pages is generated by saving document zones using IOcrDocument.SaveZones or IOcrDocument.SaveAsync not IOcrPage.SaveZones since IOcrPage.SaveZones does not save the page number.

    IOcrPage.Recognize is called to get the OCR data of the page.

    If multiple documents are used or current number of recognized pages is greater than the maximum specified in MaximumPagesBeforeLtd, then current recognition data is saved to a temporary LTD file and the OCR document is cleared.

  4. When all pages are processed their saved to result file name specified in OcrAutoRecognizeJobData.DocumentFileName using the format specified OcrAutoRecognizeJobData.Format If LTD was used, the temporary file is converted to the final document using DocumentWriter.Convert and optionally DocumentWriter.AppendLtd.

  5. All OCR documents and temporary files are deleted.

  6. The JobCompleted event is triggered.

  7. You can use the JobProgress event to show the operation progress or to abort it if threading is not used. For more information and an example, refer to OcrProgressCallback.

  8. You can use the JobOperation event to get information regarding the current operation being performed. For more information and an example, refer to JobOperation.

The IOcrAutoRecognizeManager interface also has the following options to use with this method:

Option Description
MaximumPagesBeforeLtd

Add support for converting a document with unlimited number of pages. An OCR recognition operation on a document that contains a large amount of pages (10 and more) might result in an out of memory error.

All of the LEADTOOLS OCR engines supports saving the intermediate recognition results to a temporary LTD file (DocumentFormat.LTD). The result of subsequent pages will be appended to this temporary file. When all the pages of the document have been recognized, the engine will convert the temporary LTD file to the desired output format.

The MaximumPagesBeforeLtd property defines the maximum number of pages processed as a whole. For example, if the original document has 20 pages and the value of this property is 8, the engine will recognize the first 8 pages and saves the result to a temporary file, recognizes the second 8 pages and append the results, and finally, recognize the last 4 pages and convert the temporary documentto the final format.

PreprocessPageCommands

Holds an array of OcrAutoPreprocessPageCommand items to control what auto-preprocess operation to perform on each page document prior to recognition.

MaximumThreadsPerJob

Maximum number of threads to use per job. You can instruct IOcrAutoRecognizeManager to use all available machine CPUs/cores when recognizing a document. This will greatly reduce the time required to finish the OCR operation.

JobErrorMode

Ability to resume on none critical errors. For example, if a source document has a page that could not be recognized. The offending page will be added to the final document as a graphics images and recognition will continue to the next page.

JobStarted, JobProgress, JobOperation and JobCompleted events

Events to track when both synchronous and asynchronous jobs has started, being run and completed.

AbortAllJobs

Aborts all running and pending jobs.

EnableTrace

Output debug messages to the standard .NET trace listeners.

Example
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Public Class RunJobExample
   ' Number of documents that are pending
   Private _documentsPending As Integer
   ' Event to trigger when all documents are finished
   Private _allDocumentsFinishedEvent As AutoResetEvent
   Public Sub Start()
      Dim imagesDirectory As String = LEAD_VARS.ImagesDir
      Dim documentsDirectory As String = Path.Combine(LEAD_VARS.ImagesDir, "RunJobExample")

      ' Create the the output (documents) directory
      If Not Directory.Exists(documentsDirectory) Then
         Directory.CreateDirectory(documentsDirectory)
      End If

      ' Get all TIF files in input (images) directory
      Dim imageFileNames() As String = Directory.GetFiles(imagesDirectory, "*.tif")
      If imageFileNames.Length = 0 Then
         Console.WriteLine("No images to OCR")
         Return
      End If

      ' Create a new OCR engine instance
      Dim engineType As OcrEngineType = OcrEngineType.Professional
      Console.WriteLine(String.Format("Starting up {0} engine", engineType))
      Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(engineType, False)
         ocrEngine.Startup(Nothing, Nothing, Nothing, Nothing)

         ' Setup document PDF save options: Image/Text with CCITT G4 encoding for B/W
         Dim docWriter As DocumentWriter = ocrEngine.DocumentWriterInstance
         Dim pdfOptions As PdfDocumentOptions = CType(docWriter.GetOptions(DocumentFormat.Pdf), PdfDocumentOptions)
         pdfOptions.ImageOverText = True
         pdfOptions.DocumentType = PdfDocumentType.Pdf
         pdfOptions.FontEmbedMode = DocumentFontEmbedMode.None
         pdfOptions.OneBitImageCompression = OneBitImageCompressionType.FaxG4
         docWriter.SetOptions(DocumentFormat.Pdf, pdfOptions)

         ' We are going to use multiple-threads, so disable threading in
         ' IOcrAutoRecognizeManager
         Dim autoRecognizeManager As IOcrAutoRecognizeManager = ocrEngine.AutoRecognizeManager
         autoRecognizeManager.MaximumThreadsPerJob = 1

         ' Tell the recognize manager to continue on errors
         autoRecognizeManager.JobErrorMode = OcrAutoRecognizeManagerJobErrorMode.Continue

         ' Instead of using events to trigger when documents are done,
         ' we will use the JobCompleted events of IOcrAutoRecognizeManager
         ' to decrement a counter and trigger one event when the counter reaches 0
         AddHandler autoRecognizeManager.JobStarted, AddressOf autoRecognizeManager_JobStarted
         AddHandler autoRecognizeManager.JobCompleted, AddressOf autoRecognizeManager_JobCompleted

         Dim count As Integer = imageFileNames.Length
         _documentsPending = count
         _allDocumentsFinishedEvent = New AutoResetEvent(False)

         For i As Integer = 0 To count - 1
            ' Create the job data
            Dim imageFileName As String = imageFileNames(i)
            Dim name As String = "Document " + (i + 1).ToString()
            Console.WriteLine("Queuing {0} file {1}", name, imageFileName)

            Dim data As New JobData()
            data.AutoRecognizeManager = autoRecognizeManager
            data.ImageFileName = imageFileName
            data.DocumentFileName = Path.Combine(documentsDirectory, Path.GetFileNameWithoutExtension(imageFileName) + ".pdf")
            data.JobName = name

            ' Queue this job
            ThreadPool.QueueUserWorkItem(AddressOf RunJob, data)
         Next

         ' Wait for all documents to finish
         _allDocumentsFinishedEvent.WaitOne()
         _allDocumentsFinishedEvent.Close()

         RemoveHandler autoRecognizeManager.JobStarted, AddressOf autoRecognizeManager_JobStarted
         RemoveHandler autoRecognizeManager.JobCompleted, AddressOf autoRecognizeManager_JobCompleted

         Console.WriteLine("All documents finished, check the result files in {0}", documentsDirectory)
      End Using
   End Sub

   Private Sub autoRecognizeManager_JobStarted(ByVal sender As Object, ByVal e As OcrAutoRecognizeRunJobEventArgs)
      ' This is not strictly needed in this example, we will
      ' use it to show information
      Console.WriteLine("{0} started...", e.Job.JobData.JobName)

      ' Check if we need to abort
      If AbortJobs(e.Job) Then
         ' Yes, abort all jobs
         e.Job.AutoRecognizeManager.AbortAllJobs()
      End If
   End Sub

   Private Sub autoRecognizeManager_JobCompleted(ByVal sender As Object, ByVal e As OcrAutoRecognizeRunJobEventArgs)
      Dim message As String = String.Format("{0} completed ", e.Job.JobData.JobName)

      Dim job As IOcrAutoRecognizeJob = e.Job

      ' Show any errors
      If job.Errors.Count = 0 Then
         message += "successfully..."
      Else
         message += "with errors, first error is " + job.Errors(0).Exception.Message

         ' And save the errors to a text file in the document directory
         Dim documentFileName As String = job.JobData.DocumentFileName
         Dim textPathName As String = Path.Combine(Path.GetDirectoryName(documentFileName), Path.GetFileNameWithoutExtension(documentFileName) + "_errors.txt")
         Using writer As StreamWriter = File.CreateText(textPathName)
            writer.WriteLine(job.JobData.JobName)
            writer.WriteLine("Data:")
            writer.WriteLine(" Image file name: " + job.JobData.ImageFileName)
            writer.WriteLine(" First page number: " + job.JobData.FirstPageNumber.ToString())
            writer.WriteLine(" Last page number: " + job.JobData.LastPageNumber.ToString())
            writer.WriteLine(" Format:" + job.JobData.Format.ToString())
            writer.WriteLine(" Document file name: " + job.JobData.DocumentFileName)
            writer.WriteLine("Errors:")

            For Each err As OcrAutoRecognizeManagerJobError In job.Errors
               writer.WriteLine(" Page: {0} during {1}. Error: {2}", err.ImagePageNumber, err.Operation, err.Exception.Message)
            Next
         End Using
      End If

      Console.WriteLine(message)

      ' Decrement the documents count, when we reach 0, we are done
      ' Since this will be called from multiple threads, we need
      ' to use a thread-safety procedure
      Dim pending As Integer = Interlocked.Decrement(_documentsPending)

      ' If we are the last document, wait up main thread
      If pending = 0 Then
         _allDocumentsFinishedEvent.Set()
      End If
   End Sub

   Private Class JobData
      Public AutoRecognizeManager As IOcrAutoRecognizeManager
      Public ImageFileName As String
      Public DocumentFileName As String
      Public JobName As String
   End Class

   Private Sub RunJob(ByVal state As Object)
      Dim data As JobData = CType(state, JobData)

      Console.WriteLine("Running {0}", data.JobName)

      ' Run it
      Dim jobData As New OcrAutoRecognizeJobData(data.ImageFileName, DocumentFormat.Pdf, data.DocumentFileName)
      jobData.JobName = data.JobName
      Dim job As IOcrAutoRecognizeJob = data.AutoRecognizeManager.CreateJob(jobData)
      data.AutoRecognizeManager.RunJob(job)
   End Sub

   Private Function AbortJobs(ByVal ocrJob As IOcrAutoRecognizeJob) As Boolean
      ' In your application, you can check if abortion is required, for example, if the user
      ' has pressed the Cancel button on a progress bar or if your service is shutting down.

      ' In this example, we will never abort, but you can change this code to return true
      ' upon any condition (or when a specific job is about to start)
      ' and the engine will abort all current and pending jobs
      Return False
   End Function

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class
public class RunJobExample
{
   // Number of documents that are pending
   private int _documentsPending;
   // Event to trigger when all documents are finished
   private AutoResetEvent _allDocumentsFinishedEvent;
   public void Start()
   {
      string imagesDirectory = LEAD_VARS.ImagesDir;
      string documentsDirectory = Path.Combine(LEAD_VARS.ImagesDir,"RunJobExample");

      // Create the output (documents) directory
      if(!Directory.Exists(documentsDirectory))
      {
         Directory.CreateDirectory(documentsDirectory);
      }

      // Get all TIF files in input (images) directory
      string[] imageFileNames = Directory.GetFiles(imagesDirectory, "*.tif");
      if(imageFileNames.Length == 0)
      {
         Console.WriteLine("No images to OCR");
         return;
      }

      // Create a new OCR engine instance
      OcrEngineType engineType = OcrEngineType.Professional;
      Console.WriteLine(string.Format("Starting up {0} engine", engineType));
      using(IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(engineType, false))
      {
         ocrEngine.Startup(null, null, null, null);

         // Setup document PDF save options: Image/Text with CCITT G4 encoding for B/W
         DocumentWriter docWriter = ocrEngine.DocumentWriterInstance;
         PdfDocumentOptions pdfOptions = docWriter.GetOptions(DocumentFormat.Pdf) as PdfDocumentOptions;
         pdfOptions.ImageOverText = true;
         pdfOptions.DocumentType = PdfDocumentType.Pdf;
         pdfOptions.FontEmbedMode = DocumentFontEmbedMode.None;
         pdfOptions.OneBitImageCompression = OneBitImageCompressionType.FaxG4;
         docWriter.SetOptions(DocumentFormat.Pdf, pdfOptions);

         // We are going to use multiple-threads, so disable threading in
         // IOcrAutoRecognizeManager
         IOcrAutoRecognizeManager autoRecognizeManager = ocrEngine.AutoRecognizeManager;
         autoRecognizeManager.MaximumThreadsPerJob = 1;

         // Tell the recognize manager to continue on errors
         autoRecognizeManager.JobErrorMode = OcrAutoRecognizeManagerJobErrorMode.Continue;

         // Instead of using events to trigger when documents are done,
         // we will use the JobCompleted events of IOcrAutoRecognizeManager
         // to decrement a counter and trigger one event when the counter reaches 0
         autoRecognizeManager.JobStarted += new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobStarted);
         autoRecognizeManager.JobCompleted += new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobCompleted);

         int count = imageFileNames.Length;
         _documentsPending = count;
         _allDocumentsFinishedEvent = new AutoResetEvent(false);

         for(int i = 0; i < count; i++)
         {
            // Create the job data
            string imageFileName = imageFileNames[i];
            string name = "Document " + (i + 1).ToString();
            Console.WriteLine("Queuing {0} file {1}", name, imageFileName);

            JobData data = new JobData();
            data.AutoRecognizeManager = autoRecognizeManager;
            data.ImageFileName = imageFileName;
            data.DocumentFileName = Path.Combine(documentsDirectory, Path.GetFileNameWithoutExtension(imageFileName) + ".pdf");
            data.JobName = name;

            // Queue this job
            ThreadPool.QueueUserWorkItem(new WaitCallback(RunJob), data);
         }

         // Wait for all documents to finish
         _allDocumentsFinishedEvent.WaitOne();
         _allDocumentsFinishedEvent.Close();

         autoRecognizeManager.JobStarted -= new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobStarted);
         autoRecognizeManager.JobCompleted -= new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobCompleted);

         Console.WriteLine("All documents finished, check the result files in {0}", documentsDirectory);
      }
   }

   private void autoRecognizeManager_JobStarted(object sender, OcrAutoRecognizeRunJobEventArgs e)
   {
      // This is not strictly needed in this example, we will
      // use it to show information
      Console.WriteLine("{0} started...", e.Job.JobData.JobName);

      // Check if we need to abort
      if(AbortJobs(e.Job))
      {
         // Yes, abort all jobs
         e.Job.AutoRecognizeManager.AbortAllJobs();
      }
   }

   private void autoRecognizeManager_JobCompleted(object sender, OcrAutoRecognizeRunJobEventArgs e)
   {
      string message = string.Format("{0} completed ", e.Job.JobData.JobName);

      IOcrAutoRecognizeJob job = e.Job;

      // Show any errors
      if(job.Errors.Count == 0)
      {
         message += "successfully...";
      }
      else
      {
         message += "with errors, first error is " + job.Errors[0].Exception.Message;

         // And save the errors to a text file in the document directory
         string documentFileName = job.JobData.DocumentFileName;
         string textPathName = Path.Combine(Path.GetDirectoryName(documentFileName), Path.GetFileNameWithoutExtension(documentFileName) + "_errors.txt");
         using(StreamWriter writer = File.CreateText(textPathName))
         {
            writer.WriteLine(job.JobData.JobName);
            writer.WriteLine("Data:");
            writer.WriteLine(" Image file name: " + job.JobData.ImageFileName);
            writer.WriteLine(" First page number: " + job.JobData.FirstPageNumber);
            writer.WriteLine(" Last page number: " + job.JobData.LastPageNumber);
            writer.WriteLine(" Format:" + job.JobData.Format);
            writer.WriteLine(" Document file name: " + job.JobData.DocumentFileName);
            writer.WriteLine("Errors:");

            foreach(OcrAutoRecognizeManagerJobError error in job.Errors)
            {
               writer.WriteLine(" Page: {0} during {1}. Error: {2}", error.ImagePageNumber, error.Operation, error.Exception.Message);
            }
         }
      }

      Console.WriteLine(message);

      // Decrement the documents count, when we reach 0, we are done
      // Since this will be called from multiple threads, we need
      // to use a thread-safety procedure
      int pending = Interlocked.Decrement(ref _documentsPending);

      // If we are the last document, wait up main thread
      if(pending == 0)
      {
         _allDocumentsFinishedEvent.Set();
      }
   }

   private class JobData
   {
      public IOcrAutoRecognizeManager AutoRecognizeManager;
      public string ImageFileName;
      public string DocumentFileName;
      public string JobName;
   }

   private void RunJob(object state)
   {
      JobData data = state as JobData;

      Console.WriteLine("Running {0}", data.JobName);

      // Run it
      OcrAutoRecognizeJobData jobData = new OcrAutoRecognizeJobData(data.ImageFileName, DocumentFormat.Pdf, data.DocumentFileName);
      jobData.JobName = data.JobName;
      IOcrAutoRecognizeJob job = data.AutoRecognizeManager.CreateJob(jobData);
      data.AutoRecognizeManager.RunJob(job);
   }

   private bool AbortJobs(IOcrAutoRecognizeJob ocrJob)
   {
      // In your application, you can check if abortion is required, for example, if the user
      // has pressed the Cancel button on a progress bar or if your service is shutting down.

      // In this example, we will never abort, but you can change this code to return true
      // upon any condition (or when a specific job is about to start)
      // and the engine will abort all current and pending jobs
      return false;
   }
}

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}
Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

See Also

Reference

IOcrAutoRecognizeManager Interface
IOcrAutoRecognizeManager Members
Programming with the LEADTOOLS .NET OCR
Multi-Threading with LEADTOOLS OCR
LEADTOOLS OCR Thunk Server

 

 


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RunJob requires an OCR module license and unlock key. For more information, refer to: Imaging Pro/Document/Medical Features