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Programming / Document Conversion / Converting a TIFF image to a searchable PDF document using multithreading

Converting a TIFF image to a searchable PDF document using multithreading

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Converting scanned images to searchable PDF documents is now very easy and quick process if you take advantages of the GdPicturePDF class and its OCR methods using multithreading environment. Now you can just process OCR on any converted document and the data will be added as invisible text on the page.

  • The first example shows you a very quick and easy two-steps process how it works using the GdPictureDocumentConverter class.
    Copy Code 
    'We assume that GdPicture has been correctly installed and unlocked.



Dim oGdPicturePDF As New GdPicturePDF()

'Adding the OcrPagesDone event.

AddHandler oGdPicturePDF.OcrPagesDone, AddressOf OcrPagesDone

Sub OcrPagesDone(status As GdPictureStatus) Handles oGdPicturePDF.OcrPagesDone

    'Saving the resulting document when the OCR process is finished.

    If oGdPicturePDF.SaveToFile("output.pdf") = GdPictureStatus.OK Then

        MessageBox.Show("PDF: The OCR-ed file has been saved successfully.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information)

    Else

        MessageBox.Show("PDF: The OCR-ed file has failed to save. Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error)

    End If

End Sub



Dim status As GdPictureStatus = GdPictureStatus.OK

'First step - Converting your source TIF file to PDF document.

Using oConverter As GdPictureDocumentConverter = New GdPictureDocumentConverter()

    status = oConverter.LoadFromFile("input.tif", GdPicture14.DocumentFormat.DocumentFormatTIFF)

    If status = GdPictureStatus.OK Then

        status = oConverter.SaveAsPDF("output.pdf", PdfConformance.PDF)

        If status = GdPictureStatus.OK Then

            MessageBox.Show("Converter: The PDF file has been saved successfully.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information)

        Else

            MessageBox.Show("Converter: The PDF file has failed to save. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error)

        End If

    Else

        MessageBox.Show("Converter: The TIF file has failed to load. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error)

    End If

End Using

'Second step - Processing OCR on the created PDF document.

If status = GdPictureStatus.OK Then

    status = oGdPicturePDF.LoadFromFile("output.pdf", False)

    If status = GdPictureStatus.OK Then

        status = oGdPicturePDF.OcrPages("*", 0, "eng", "C:\GdPicture.NET 14\Redist\OCR", "", 300, 2, True)

        If status = GdPictureStatus.OK Then

            MessageBox.Show("PDF: The OCR process has been finished successfully.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information)

        Else

            MessageBox.Show("PDF: The OCR process has failed. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error)

        End If

    Else

        MessageBox.Show("PDF: The PDF file has failed to load. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error)

    End If

End If



'Releasing resources only if all processes are finished.

oGdPicturePDF.Dispose()
    Copy Code 
    //We assume that GdPicture has been correctly installed and unlocked.



GdPicturePDF oGdPicturePDF = new GdPicturePDF();

//Adding the OcrPagesDone event.

oGdPicturePDF.OcrPagesDone += OcrPagesDone;



void OcrPagesDone(GdPictureStatus status)

{

    //Saving the resulting document when the OCR process is finished.

    if (oGdPicturePDF.SaveToFile("output.pdf") == GdPictureStatus.OK)

        MessageBox.Show("PDF: The OCR-ed file has been saved successfully.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information);

    else

       MessageBox.Show("PDF: The OCR-ed file has failed to save. Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error);

}



GdPictureStatus status = GdPictureStatus.OK;

//First step - Converting your source TIF file to PDF document.

using (GdPictureDocumentConverter oConverter = new GdPictureDocumentConverter())

{

    status = oConverter.LoadFromFile("input.tif", GdPicture14.DocumentFormat.DocumentFormatTIFF);

    if (status == GdPictureStatus.OK)

    {

        status = oConverter.SaveAsPDF("output.pdf", PdfConformance.PDF);

        if (status == GdPictureStatus.OK)

        {

            MessageBox.Show("Converter: The PDF file has been saved successfully.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information);

        }

        else

        {

            MessageBox.Show("Converter: The PDF file has failed to save. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error);

        }

    }

    else

    {

        MessageBox.Show("Converter: The TIF file has failed to load. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error);

    }

}

//Second step - Processing OCR on the created PDF document.

if (status == GdPictureStatus.OK)

{

    status = oPDF.LoadFromFile("output.pdf", false);

    if (status == GdPictureStatus.OK)

    {

        status = oGdPicturePDF.OcrPages("*", 0, "eng", "C:\\GdPicture.NET 14\\Redist\\OCR", "", 300, 2, true);

        if (status == GdPictureStatus.OK)

        {

            MessageBox.Show("PDF: The OCR process has been finished successfully.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information);

        }

        else

        {

            MessageBox.Show("PDF: The OCR process has failed. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error);

        }

    }

    else

    {

        MessageBox.Show("PDF: The PDF file has failed to load. Status: " + status.ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error);

    }

}



//Releasing resources only if all processes are finished.

oGdPicturePDF.Dispose();
  •  The second example demonstrates it using another approach by converting page by page to images through the GdPictureImaging class.
    Copy Code 
    'We assume that GdPicture has been correctly installed and unlocked.



Dim oGdPicturePDF As New GdPicturePDF()

'Adding the OcrPagesDone event.

AddHandler oGdPicturePDF.OcrPagesDone, AddressOf OcrPagesDone



Sub OcrPagesDone(status As GdPictureStatus) Handles oGdPicturePDF.OcrPagesDone

    'Saving the resulting document when the OCR process is finished.

    If oGdPicturePDF.SaveToFile("output.pdf") = GdPictureStatus.OK Then

        MessageBox.Show("The resulting document is saved.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information)

    Else

        MessageBox.Show("The resulting document can't be saved. Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error)

    End If

End Sub



Using oGdPictureImaging As New GdPictureImaging()

    'Loading an image from a file.

    Dim imageId As Integer = oGdPictureImaging.CreateGdPictureImageFromFile("image.tif")

    If oGdPictureImaging.GetStat() = GdPictureStatus.OK Then

        If oGdPicturePDF.NewPDF() = GdPictureStatus.OK Then

            If oGdPictureImaging.TiffIsMultiPage(imageId) = False Then

                'One-page tiff image.

                'Adding an image as a resource and drawing it onto a new page.

                oGdPicturePDF.AddImageFromGdPictureImage(imageId, false, false)

            Else

                'Multi-page tiff image.

                Dim NumberOfPages As Integer = oGdPictureImaging.TiffGetPageCount(imageId)

                'Loop through pages.

                For i As Integer = 1 To NumberOfPages

                    'Selecting each page in the tiff file.

                    If oGdPictureImaging.TiffSelectPage(imageId, i) = GdPictureStatus.OK Then

                        'Adding the selected tiff page as a resource to a PDF document and drawing it on a new page.

                        oGdPicturePDF.AddImageFromGdPictureImage(imageId, false, false)

                        If oGdPicturePDF.GetStat() <> GdPictureStatus.OK Then

                            Exit For

                        End If

                    Else

                        Exit For

                    End If

                Next

            End If

            'Checking whether any error occurred in adding any image to the PDF document.

            If oGdPicturePDF.GetStat() = GdPictureStatus.OK Then

                If oGdPicturePDF.OcrPages("*", 0, "eng", "C:\GdPicture.NET 14\Redist\OCR", "", 300, 2, True) = GdPictureStatus.OK Then

                    MessageBox.Show("OcrPages done! Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information)

                End If

            End If

        End If

        MessageBox.Show("Finished! Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information)

        'Clearing resource.

        oGdPictureImaging.ReleaseGdPictureImage(imageId)

    Else

        MessageBox.Show("The image file can't be loaded. Status: " + oGdPictureImaging.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error)

    End If

End Using



'Releasing resources only if all processes are finished.

oGdPicturePDF.Dispose()
    Copy Code 
    //We assume that GdPicture has been correctly installed and unlocked.



GdPicturePDF oGdPicturePDF = new GdPicturePDF();

//Adding the OcrPagesDone event.

oGdPicturePDF.OcrPagesDone += OcrPagesDone;



void OcrPagesDone(GdPictureStatus status)

{

    //Saving the resulting document when the OCR process is finished.

    if (oGdPicturePDF.SaveToFile("output.pdf") == GdPictureStatus.OK)

        MessageBox.Show("The resulting document is saved.", "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information);

    else

        MessageBox.Show("The resulting document can't be saved. Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error);

}



using (GdPictureImaging oGdPictureImaging = new GdPictureImaging())

{

    //Loading an image from a file.

    int imageId = oGdPictureImaging.CreateGdPictureImageFromFile("image.tif");

    if (oGdPictureImaging.GetStat() == GdPictureStatus.OK)

    {

        if (oGdPicturePDF.NewPDF() == GdPictureStatus.OK)

        {

            if (oGdPictureImaging.TiffIsMultiPage(imageId) == false) //One-page tiff image.

            {

                //Adding an image as a resource and drawing it onto a new page.

                oGdPicturePDF.AddImageFromGdPictureImage(imageId, false, false);

            }

            else //Multi-page tiff image.

            {

                int NumberOfPages = oGdPictureImaging.TiffGetPageCount(imageId);

                //Loop through pages.

                for (int i = 1; i <= NumberOfPages; i++)

                {

                    //Selecting each page in a tiff file.

                    if (oGdPictureImaging.TiffSelectPage(imageId, i) == GdPictureStatus.OK)

                    {

                        //Adding the selected tiff page as a resource to a PDF document and drawing it on a new page.

                        oGdPicturePDF.AddImageFromGdPictureImage(imageId, false, false);

                        if (oGdPicturePDF.GetStat() != GdPictureStatus.OK)

                            break;

                    }

                    else

                        break;

                }

            }

            //Checking whether any error occurred in adding any image to the PDF document.

            if (oGdPicturePDF.GetStat() == GdPictureStatus.OK)

            {

                if (oGdPicturePDF.OcrPages("*", 0, "eng", @"C:\GdPicture.NET 14\Redist\OCR", "", 300, 2, true) == GdPictureStatus.OK)

                    MessageBox.Show("OcrPages done! Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information);

            }

        }

        MessageBox.Show("Finished! Status: " + oGdPicturePDF.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Information);

        //Clearing resource.

        oGdPictureImaging.ReleaseGdPictureImage(imageId);

    }

    else

    {

        MessageBox.Show("The image file can't be loaded. Status: " + oGdPictureImaging.GetStat().ToString(), "TIFF to PDF Example", MessageBoxButtons.OK, MessageBoxIcon.Error);

    }

}



//Releasing resources only if all processes are finished.

oGdPicturePDF.Dispose();