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Run(Stream,string,DocumentFormat,string,OcrProgressCallback) Method


Converts an image in a stream to a document file in the specified document format with optional multipage zone file.

Public Sub Run( 
   ByVal imageStream As Stream, 
   ByVal documentFileName As String, 
   ByVal format As DocumentFormat, 
   ByVal zonesFileName As String, 
   ByVal callback As OcrProgressCallback 


The stream containing the image data.

The name of the resulting document file.

The output document format. If this parameter is DocumentFormat.User, then the document is saved using the native engine format set in IOcrDocumentManager.EngineFormat, if the engine used supports native formats. Otherwise, an exception will be thrown.

Optional name of prepared multipage zone file. This parameter can be a null (Nothing in VB) reference.

Optional callback to show operation progress.

This method will perform the following operations:

  1. The JobStarted event is triggered.

  2. Creates one or more IOcrDocument object to store the pages into. The number of OCR documents created is dependent 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. The document will be created as disk-based.

  3. Loops through all the pages in imageStream and for each page:

    • The page is created using IOcrEngine.CreatePage.

    • If zonesFileName contains a valid multipage 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 zonesFileName is a null (Nothing in VB) reference or it does not contain an equivalent page number, auto-decomposing of the page is performed instead with IOcrPage.AutoZone.

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

    • For LEADTOOLS OCR Module - LEAD Engine, the page is added to the document using IOcrDocument.Pages.Add.

    • For engines other than LEADTOOLS OCR Module - LEAD Engine: 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 they are saved to result file name specified in documentFileName using the format specified in 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 or callback 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

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 save the result to a temporary file, recognize the second 8 pages and append the results, and finally, recognize the last 4 pages and convert the temporary document into the final format.


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


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.


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.


Aborts all running and pending jobs.


Output debug messages to the standard .NET trace listeners.


Target Platforms

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