Erkennen des Geburtsdatums auf einem OMR-Formular in .NET

Das VintaSoft Imaging .NET SDK, ergänzt durch das VintaSoft Forms Processing .NET Plug-in, ermöglicht die Erkennung optischer Markierungen (OMR) auf ausgefüllten Formularen.

Dieser Artikel erklärt, wie das Geburtsdatum aus dem Bild eines OMR-Formulars erkannt wird.

Hier ist das Bild der OMR-Formularvorlage zum Ausfüllen des Geburtsdatums:
Image of OMR form template for filling date of birth

Image of OMR form template for filling date of birth

Vor der Erkennung des OMR-Formulars muss eine Formularseitenvorlage erstellt werden, die alle auf der Formularseite vorhandenen Felder definiert:

Erstellen Sie eine Tabellenvorlage, die optische Markierungen für die Eingabe der ersten Ziffer des Geburtsdatums zusammenfasst
Erstellen Sie eine Tabellenvorlage, die optische Markierungen für die Eingabe der zweiten Ziffer des Geburtsdatums zusammenfasst
Erstellen Sie eine Feldgruppenvorlage für das Geburtsdatum als Zusammenführung der Tabellenvorlagen für die erste und zweite Ziffer
Erstellen Sie eine Tabellenvorlage, die optische Markierungen für die Eingabe des Geburtsmonats zusammenfasst
Erstellen Sie eine Tabellenvorlage, die optische Markierungen für die Eingabe der ersten beiden Ziffern des Geburtsjahres zusammenfasst Geburtsdatum
Tabellenvorlage erstellen,
Erstellen einer Feldgruppenvorlage für das Geburtsjahr als Zusammenführung von Tabellenvorlagen für das erste und letzte Ziffernpaar des Geburtsjahres
Erstellen einer Feldgruppenvorlage für das Geburtsdatum als Zusammenführung von Tabellenvorlagen für Tag, Monat und Jahr
Erstellen einer Formularseitenvorlage und Hinzufügen der Feldgruppenvorlage für das Geburtsdatum

Hier ist der C#-Code, der zeigt, wie eine Formularseitenvorlage erstellt wird, die OMR-Felder mit Informationen zum Geburtsdatum enthält:

/// <summary>
/// Creates a page template with birth date.
/// </summary>
/// <returns>A page template with birth date.</returns>
private static Vintasoft.Imaging.FormsProcessing.FormRecognition.FormPageTemplate CreatePageTemplateWithBirthDate()
{
    // create an OMR field template table for the first digit of day
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable dayPart1Template = CreateTemplateTableForFirstDigitInDay();
    // create an OMR field template table for the second digit of day
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable dayPart2Template = CreateTemplateTableForSecondDigitInDay();
    // create a form field template group for day
    Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplateGroup dayTemplate = CreateTemplateGroup(
        "Day", "{0}{1}", dayPart1Template, dayPart2Template);


    // create an OMR field template table for month
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable monthTemplate = CreateTemplateTableForMonth();


    // create an OMR field template table for the first 2 digits of year
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable yearPart1Template = CreateTemplateTableForFirstTwoDigitsInYear();
    // create an OMR field template table for the last 2 digits of year
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable yearPart2Template = CreateTemplateTableForLastTwoDigitsInYear();
    // create a form field template group for year
    Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplateGroup yearTemplate = CreateTemplateGroup(
        "Year", "{0}{1}", yearPart1Template, yearPart2Template);


    // create birth date template as a group of day, month and year templates
    Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplateGroup dateOfBirthTemplate = CreateTemplateGroup(
        "Date of Birth", "{0}.{1}.{2}", dayTemplate, monthTemplate, yearTemplate);


    // create an empty page template
    Vintasoft.Imaging.FormsProcessing.FormRecognition.FormPageTemplate pageTemplate =
        new Vintasoft.Imaging.FormsProcessing.FormRecognition.FormPageTemplate();

    // add birth date template to the page template
    pageTemplate.Items.Add(dateOfBirthTemplate);

    return pageTemplate;
}

/// <summary>
/// Creates an OMR field template table for the first digit of day.
/// </summary>
/// <returns>An OMR field template table for the first digit of day.</returns>
private static Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable CreateTemplateTableForFirstDigitInDay()
{
    // create template table
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable result =
        new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable();

    // update table properties
    result.Name = "D1";
    result.ColumnCount = 1;
    result.RowCount = 4;
    result.Orientation = Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrTableOrientation.Vertical;
    result.DistanceBetweenColumns = 0.2f;
    result.DistanceBetweenRows = 0.2f;

    // update cell values

    result.CellValues[0, 0] = "0";
    result.CellValues[1, 0] = "1";
    result.CellValues[2, 0] = "2";
    result.CellValues[3, 0] = "3";

    // create table cell template
    result.CellTemplate = new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrEllipticalFieldTemplate();
    result.CellTemplate.FilledThreshold = 0.4f;

    // set table bounding box
    result.BoundingBox = new System.Drawing.RectangleF(6, 65, 20, 85);

    return result;
}

/// <summary>
/// Creates an OMR field template table for the second digit of day.
/// </summary>
/// <returns>An OMR field template table for the second digit of day.</returns>
private static Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable CreateTemplateTableForSecondDigitInDay()
{
    // create template table
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable result =
        new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable();

    // update table properties
    result.Name = "D2";
    result.ColumnCount = 1;
    result.RowCount = 10;
    result.Orientation = Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrTableOrientation.Vertical;
    result.DistanceBetweenColumns = 0.2f;
    result.DistanceBetweenRows = 0.2f;

    // update cell values

    result.CellValues[0, 0] = "0";
    result.CellValues[1, 0] = "1";
    result.CellValues[2, 0] = "2";
    result.CellValues[3, 0] = "3";
    result.CellValues[4, 0] = "4";
    result.CellValues[5, 0] = "5";
    result.CellValues[6, 0] = "6";
    result.CellValues[7, 0] = "7";
    result.CellValues[8, 0] = "8";
    result.CellValues[9, 0] = "9";

    // create table cell template
    result.CellTemplate = new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrEllipticalFieldTemplate();
    result.CellTemplate.FilledThreshold = 0.4f;

    // set table bounding box
    result.BoundingBox = new System.Drawing.RectangleF(29, 65, 19, 216);

    return result;
}

/// <summary>
/// Creates an OMR field template table for the month.
/// </summary>
/// <returns>An OMR field template table for the month.</returns>
private static Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable CreateTemplateTableForMonth()
{
    // create template table
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable result =
        new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable();

    // update table properties
    result.Name = "Month";
    result.ColumnCount = 1;
    result.RowCount = 12;
    result.Orientation = Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrTableOrientation.Vertical;
    result.DistanceBetweenColumns = 0.2f;
    result.DistanceBetweenRows = 0.2f;

    // update cell values

    result.CellValues[0, 0] = "1";
    result.CellValues[1, 0] = "2";
    result.CellValues[2, 0] = "3";
    result.CellValues[3, 0] = "4";
    result.CellValues[4, 0] = "5";
    result.CellValues[5, 0] = "6";
    result.CellValues[6, 0] = "7";
    result.CellValues[7, 0] = "8";
    result.CellValues[8, 0] = "9";
    result.CellValues[9, 0] = "10";
    result.CellValues[9, 0] = "11";
    result.CellValues[9, 0] = "12";

    // create table cell template
    result.CellTemplate = new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrEllipticalFieldTemplate();
    result.CellTemplate.FilledThreshold = 0.4f;

    // set table bounding box
    result.BoundingBox = new System.Drawing.RectangleF(59, 66, 15, 214);

    return result;
}

/// <summary>
/// Creates an OMR field template table for the first 2 digits of year.
/// </summary>
/// <returns>An OMR field template table for the first 2 digits of year.</returns>
private static Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable CreateTemplateTableForFirstTwoDigitsInYear()
{
    // create template table
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable result =
        new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable();

    // update table properties
    result.Name = "Y1";
    result.ColumnCount = 2;
    result.RowCount = 2;
    result.Orientation = Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrTableOrientation.Vertical;
    result.DistanceBetweenColumns = 0.2f;
    result.DistanceBetweenRows = 0.2f;

    // update cell values

    result.CellValues[0, 0] = "1";
    result.CellValues[0, 1] = "9";
    result.CellValues[1, 0] = "2";
    result.CellValues[1, 1] = "0";

    // create table cell template
    result.CellTemplate = new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrEllipticalFieldTemplate();
    result.CellTemplate.FilledThreshold = 0.4f;

    // set table bounding box
    result.BoundingBox = new System.Drawing.RectangleF(154, 65, 42, 40);

    return result;
}

/// <summary>
/// Creates an OMR field template table for the last 2 digits of year.
/// </summary>
/// <returns>An OMR field template table for the last 2 digits of year.</returns>
private static Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable CreateTemplateTableForLastTwoDigitsInYear()
{
    // create template table
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable result =
        new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrFieldTemplateTable();

    // update table properties
    result.Name = "Y2";
    result.ColumnCount = 2;
    result.RowCount = 10;
    result.Orientation = Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrTableOrientation.Vertical;
    result.DistanceBetweenColumns = 0.2f;
    result.DistanceBetweenRows = 0.2f;

    // update cell values

    result.CellValues[0, 0] = "0";
    result.CellValues[0, 1] = "0";
    result.CellValues[1, 0] = "1";
    result.CellValues[1, 1] = "1";
    result.CellValues[2, 0] = "2";
    result.CellValues[2, 1] = "2";
    result.CellValues[3, 0] = "3";
    result.CellValues[3, 1] = "3";
    result.CellValues[4, 0] = "4";
    result.CellValues[4, 1] = "4";
    result.CellValues[5, 0] = "5";
    result.CellValues[5, 1] = "5";
    result.CellValues[6, 0] = "6";
    result.CellValues[6, 1] = "6";
    result.CellValues[7, 0] = "7";
    result.CellValues[7, 1] = "7";
    result.CellValues[8, 0] = "8";
    result.CellValues[8, 1] = "8";
    result.CellValues[9, 0] = "9";
    result.CellValues[9, 1] = "9";

    // create table cell template
    result.CellTemplate = new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrEllipticalFieldTemplate();
    result.CellTemplate.FilledThreshold = 0.4f;

    // set table bounding box
    result.BoundingBox = new System.Drawing.RectangleF(199, 65, 41, 216);

    return result;
}

/// <summary>
/// Creates the form field template group.
/// </summary>
/// <param name="name">The group name.</param>
/// <param name="valueFormat">The group value format.</param>
/// <param name="items">The group items.</param>
private static Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplateGroup CreateTemplateGroup(
    string name,
    string valueFormat,
    params Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplate[] items)
{
    // create a form field template group
    Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplateGroup result =
        new Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplateGroup();
    // add item to the form field template group
    result.Items.AddRange(items);

    // set name of form field template group
    result.Name = name;
    // set value format of form field template group
    result.ValueFormat = valueFormat;

    return result;
}

Nachdem die Formularseitenvorlage fertig ist, kann die Erkennung der ausgefüllten Formularseite gestartet werden.

Hier ist das Bild (100 dpi Auflösung) eines ausgefüllten, nicht gedrehten OMR-Formulars, das das Geburtsdatum speichert:
An image (100dpi) of filled non-rotated OMR form, which stores the date of birth

An image (100dpi) of filled non-rotated OMR form, which stores the date of birth

Hier ist das Bild (200 dpi Auflösung) eines ausgefüllten, nicht gedrehten OMR-Formulars, das das Geburtsdatum speichert:
An image (200dpi) of filled non-rotated OMR form, which stores the date of birth

An image (200dpi) of filled non-rotated OMR form, which stores the date of birth

Hier ist das Bild (300 dpi Auflösung) eines ausgefüllten, nicht gedrehten OMR-Formulars, das das Geburtsdatum speichert:
An image (300dpi) of filled non-rotated OMR form, which stores the date of birth

An image (300dpi) of filled non-rotated OMR form, which stores the date of birth

Hier ist das Bild eines ausgefüllten, um 20 Grad gedrehten OMR-Formulars, das das Geburtsdatum speichert:
An image of filled rotated (20 degrees) OMR form, which stores the date of birth

An image of filled rotated (20 degrees) OMR form, which stores the date of birth

Hier ist das Bild eines ausgefüllten, um 150 Grad gedrehten OMR-Formulars, das das Geburtsdatum speichert:
An image of filled rotated (150 degrees) OMR form, which stores the date of birth

An image of filled rotated (150 degrees) OMR form, which stores the date of birth

Hier ist der C#-Code, der zeigt, wie das OMR-Formular mit dem Geburtsdatum aus dem Bild der ausgefüllten Formularseite erkannt wird:

/// <summary>
/// Recognizes the birth date in filled OMR form.
/// </summary>
/// <param name="templateImagePath">A path to an image that represents a form template for filling the birth date.</param>
/// <param name="filledImagePath">A path to an image that represents filled form with the birth date.</param>
public static void RecognizeBirthDateInFilledOmrForm(string templateImagePath, string filledImagePath)
{
    // open an image that represents a form template for filling the birth date
    using (Vintasoft.Imaging.VintasoftImage templateImage = new Vintasoft.Imaging.VintasoftImage(templateImagePath))
    {
        // create a template manager
        Vintasoft.Imaging.FormsProcessing.FormRecognition.FormTemplateManager formTemplateManager =
            new Vintasoft.Imaging.FormsProcessing.FormRecognition.FormTemplateManager();
        // create a page template with birth date
        Vintasoft.Imaging.FormsProcessing.FormRecognition.FormPageTemplate formPageTemplate = CreatePageTemplateWithBirthDate();
        // add template image and page template to the template manager
        formTemplateManager.AddPageTemplate(templateImage, formPageTemplate);

        // open an image that represents filled form with the birth date
        using (Vintasoft.Imaging.VintasoftImage filledImage = new Vintasoft.Imaging.VintasoftImage(filledImagePath))
        {
            // recognize filled form with birth date
            RecognizeFilledFormInImage(formTemplateManager, filledImage);
        }
    }
}

/// <summary>
/// Recognizes filled form in an image.
/// </summary>
/// <param name="templateManager">The template manager that contains information about form template.</param>
/// <param name="image">An image that represents filled form.</param>
private static void RecognizeFilledFormInImage(
    Vintasoft.Imaging.FormsProcessing.FormRecognition.FormTemplateManager templateManager,
    Vintasoft.Imaging.VintasoftImage image)
{
    // create the template matching command
    Vintasoft.Imaging.FormsProcessing.TemplateMatching.TemplateMatchingCommand templateMatchingCommand =
        new Vintasoft.Imaging.FormsProcessing.TemplateMatching.TemplateMatchingCommand();
    // set the minimum confidence
    templateMatchingCommand.MinConfidence = 0.5f;
    // set template images
    templateMatchingCommand.TemplateImages = templateManager.TemplateImages;

    // create the form recognition manager
    Vintasoft.Imaging.FormsProcessing.FormRecognitionManager formRecognitionManager =
        new Vintasoft.Imaging.FormsProcessing.FormRecognitionManager(templateMatchingCommand, templateManager);

    // subscribe to the FormRecognitionResult.ImageRecognitionError event to output recognition errors
    formRecognitionManager.ImageRecognitionError += RecognitionManager_ImageRecognitionError;

    // recognize form in image
    Vintasoft.Imaging.FormsProcessing.FormRecognitionResult formRecognitionResult = formRecognitionManager.Recognize(image);

    // unsubscribe from FormRecognitionResult.ImageRecognitionError event
    formRecognitionManager.ImageRecognitionError -= RecognitionManager_ImageRecognitionError;

    // if recognition is failed
    if (formRecognitionResult == null)
        return;

    // get the result of image comparison
    Vintasoft.Imaging.FormsProcessing.TemplateMatching.ImageImprintCompareResult imageImprintCompareResult =
        formRecognitionResult.TemplateMatchingResult.ImageCompareResult;
    // if image comparison result is NOT reliable
    if (!imageImprintCompareResult.IsReliable)
    {
        // matching template is not found
        System.Console.WriteLine("Matching template is not found.");
    }
    // if image comparison result is reliable
    else
    {
        // get recognized form page
        Vintasoft.Imaging.FormsProcessing.FormRecognition.FormPage recognizedPage = formRecognitionResult.RecognizedPage;
        // write page info
        System.Console.WriteLine(string.Format(
            "Matching template: {0}; confidence: {1:F1}%.",
            recognizedPage.Name,
            imageImprintCompareResult.Confidence * 100));

        // get form field count
        if (recognizedPage.Items.Count == 0)
        {
            System.Console.WriteLine("No form fields were recognized.");
        }
        else
        {
            System.Console.WriteLine(string.Format(
                "Recognized form field count: {0}",
                recognizedPage.Items.Count));
            // for each recognized form field
            foreach (Vintasoft.Imaging.FormsProcessing.FormRecognition.FormField recognizedField in recognizedPage.Items)
            {
                // write field info to the console
                System.Console.WriteLine(string.Format(
                    "  Name: {0}; value: {1}; confidence: {2:F1}%",
                    recognizedField.Name,
                    recognizedField.Value,
                    recognizedField.Confidence * 100));
            }
        }
    }
}

/// <summary>
/// Handles the ImageRecognitionError event of the FormRecognitionManager.
/// </summary>
private static void RecognitionManager_ImageRecognitionError(
    object sender,
    Vintasoft.Imaging.FormsProcessing.FormRecognitionErrorEventArgs e)
{
    // writes information about form recognition error to the console
    System.Console.WriteLine(e.Exception.Message);
}