Choosing the appropriate OCR zone in VB.NET

This example shows how to choose the appropriate OCR context. OCR context is easy to set and use, and it’s important in the OCR process. Often on your forms, you don’t want to recognize all the text in the document, but only small parts of it — whether it’s a column in a table, a name on a forum, or an additional notes area. You have to inform the OCR engine of the layout type of the data you want to process using OCR.

VB.NET
 
'We assume that GdPicture has been correctly installed and unlocked.
'We assume a GdViewer object called GdViewer1 has been created and painted on the form.
Dim oGdPictureImaging As New GdPictureImaging()
'Loading the image from a file.
Dim imageId As Integer = oGdPictureImaging.CreateGdPictureImageFromFile("image.tif")
'Checking if the image has been loaded correctly.
If oGdPictureImaging.GetStat() <> GdPictureStatus.OK Then
    MessageBox.Show("The image can't be loaded. Error: " + oGdPictureImaging.GetStat().ToString(), "OCR Context Example", MessageBoxButtons.OK, MessageBoxIcon.Error)
Else
    'Displaying the image in the GdViewer.
    GdViewer1.DisplayFromGdPictureImage(imageId)
    oGdPictureImaging.ReleaseGdPictureImage(imageId)
End If
oGdPictureImaging.Dispose()
'On the Mouse UP event on the GdViewer, set the ROI based on the rectangle of selection of the GdViewer.
'If a rectangle of selection is painted on the GdViewer, the area will be OCRed with a single line OCR context.
Public Sub OCR_ROI_MouseUP(eventSender As System.Object, eventArgs As System.EventArgs)
    Dim oGdPictureOCR As GdPictureOCR = New GdPictureOCR()
    'Initializing variables to hold the position of the rectangle of selection on the document.
    Dim leftArea As Integer = 0
    Dim topArea As Integer = 0
    Dim widthArea As Integer = 0
    Dim heightArea As Integer = 0
    'Checking if a rectangle of selection has been painted on the GdViewer.
    If GdViewer1.IsRect() Then
        'Getting the location of the selection on the document.
        GdViewer1.GetRectCoordinatesOnDocument(leftArea, topArea, widthArea, heightArea)
        'Setting the ROI on the document.
        oGdPictureOCR.SetROI(leftArea, topArea, widthArea, heightArea)
    Else
        oGdPictureOCR.ResetROI()
    End If
    'Processing the OCR:
    'Selecting the OCR context, here we will use it to recognize a single line on our form.
    oGdPictureOCR.Context = OCRContext.OCRContextSingleLine
    'Setting up the required parameters for the OCR engine.
    oGdPictureOCR.ResourceFolder = "Redist\OCR"
    If (oGdPictureOCR.AddLanguage(OCRLanguage.English) = GdPictureStatus.OK) AndAlso
        (oGdPictureOCR.SetImage(imageId) = GdPictureStatus.OK) Then
        'Running the OCR.
        Dim resID As String = oGdPictureOCR.RunOCR()
        'Checking the status.
        If oGdPictureOCR.GetStat() <> GdPictureStatus.OK Then
            MessageBox.Show("The OCR has failed with the status: " + oGdPictureOCR.GetStat().ToString(), "OCR Context Example", MessageBoxButtons.OK, MessageBoxIcon.Error)
        Else
            'Checking the results.
            For i As Integer = 1 To oGdPictureOCR.GetCharacterCount(resID)
                oGdPictureImaging.DrawRectangle(imageId,
                    oGdPictureOCR.GetCharacterLeft(resID, i) + leftArea,
                    oGdPictureOCR.GetCharacterTop(resID, i) + topArea,
                    oGdPictureOCR.GetCharacterRight(resID, i) - oGdPictureOCR.GetCharacterLeft(resID, i),
                    oGdPictureOCR.GetCharacterBottom(resID, i) - oGdPictureOCR.GetCharacterTop(resID, i),
                    1, Color.Red, False)


            Next
        End If
    End If
    oGdPictureOCR.Dispose()
End Sub

This code sample is an example that illustrates how to use our SDK. Please adapt it to your specific use case.