# Convert images into searchable PDF/A files in C#

This guide explains how to convert image files to searchable PDF/A files. Nutrient.NET SDK’s (formerly GdPicture.NET) optical character recognition (OCR) engine enables you to recognize text in an image file and then save the text in a PDF/A file.

## Converting image files to searchable PDF/A files

This section explains how to convert simple, single-page image files. For more information on converting multipage image files, see [Converting Multipage TIFF Files to Searchable PDF/A Files](#converting-multipage-tiff-files-to-searchable-pdf-a-files).

To convert an image file to a searchable PDF/A file, follow the steps outlined below:

1. Create a `GdPictureImaging` object and a `GdPictureOCR` object.

2. Select the image by passing its path to the `CreateGdPictureImageFromFile` method of the `GdPictureImaging` object.

3. Configure the OCR process with the `GdPictureOCR` object in the following way:
   - Set the image with the `SetImage` method.
   - Set the path to the OCR resource folder with the `ResourceFolder` property. The default language resources are located in `GdPicture.NET 14\Redist\OCR`. For more information on adding language resources, see the [language support](https://www.nutrient.io/guides/dotnet/ocr/language-support.md) guide.
   - With the `AddLanguage` method, add the language resources that Nutrient.NET SDK uses to recognize text in the image. This method takes a member of the `OCRLanguage` enumeration.
   - Optional: Set whether OCR prioritizes recognition accuracy or speed with the `OCRMode` property.
   - Optional: Set the character allowlist with the `CharacterSet` property. When scanning the image, the OCR engine only recognizes the characters included in the allowlist.
   - Optional: Set the character denylist with the `CharacterBlackList` property. When scanning the image, the OCR engine ignores the characters included in the denylist.

4. Run the OCR process with the `RunOCR` method of the `GdPictureOCR` object.

5. Get the result of the OCR process as text with the `GetOCRResultText` method of the `GdPictureOCR` object.

6. Create the output with the `CreateFromText` method of the `GdPicturePDF` object. The first parameter sets the conformance level of the PDF document. This parameter is an element of the `PdfConformance` enum. For example, use `PDF_A_4f` to create a document with conformance level PDF/A-4f.

7. Save the output in a PDF document.

The example below converts an image file to a searchable PDF/A-4f file by only specifying the language of the text:

### C#

```csharp

using GdPicturePDF gdpicturePDF = new GdPicturePDF();
using GdPictureImaging gdpictureImaging = new GdPictureImaging();
using GdPictureOCR gdpictureOCR = new GdPictureOCR();
// Select the image to process.
int imageID = gdpictureImaging.CreateGdPictureImageFromFile(@"C:\temp\source.png");
// Set the OCR parameters.
gdpictureOCR.SetImage(imageID);
gdpictureOCR.ResourceFolder = @"C:\GdPicture.NET 14\Redist\OCR";
gdpictureOCR.AddLanguage(OCRLanguage.English);
// Run the OCR process.
string resID = gdpictureOCR.RunOCR();
// Get the result of the OCR process as text.
string content = gdpictureOCR.GetOCRResultText(resID);
// Save the result in a PDF document.
gdpicturePDF.CreateFromText(PdfConformance.PDF_A_4f, 595, 842, 10, 10, 10, 10,
    TextAlignment.TextAlignmentNear, content, 12, "Arial", false, false, true, false);
gdpicturePDF.SaveToFile(@"C:\temp\output.pdf");
gdpictureImaging.ReleaseGdPictureImage(imageID);

```

### VB.NET

```vb

Using gdpicturePDF As GdPicturePDF = New GdPicturePDF()
Using gdpictureImaging As GdPictureImaging = New GdPictureImaging()
Using gdpictureOCR As GdPictureOCR = New GdPictureOCR()
    ' Select the image to process.
    Dim imageID As Integer = gdpictureImaging.CreateGdPictureImageFromFile("C:\temp\source.png")
    ' Set the OCR parameters.
    gdpictureOCR.SetImage(imageID)
    gdpictureOCR.ResourceFolder = "C:\GdPicture.NET 14\Redist\OCR"
    gdpictureOCR.AddLanguage(OCRLanguage.English)
    ' Run the OCR process.
    Dim resID As String = gdpictureOCR.RunOCR()
    ' Get the result of the OCR process as text.
    Dim content As String = gdpictureOCR.GetOCRResultText(resID)
    ' Save the result in a PDF document.
    gdpicturePDF.CreateFromText(PdfConformance.PDF_A_4f, 595, 842, 10, 10, 10, 10,
        TextAlignment.TextAlignmentNear, content, 12, "Arial", False, False, True, False)
    gdpicturePDF.SaveToFile("C:\temp\output.pdf")
    gdpictureImaging.ReleaseGdPictureImage(imageID)
End Using
End Using
End Using

```

The example below converts an image file to a searchable PDF/A-4f file. It specifies two languages, favors speed over accuracy, and disregards numbers when scanning the image:

### C#

```csharp

using GdPicturePDF gdpicturePDF = new GdPicturePDF();
using GdPictureImaging gdpictureImaging = new GdPictureImaging();
using GdPictureOCR gdpictureOCR = new GdPictureOCR();
// Select the image to process.
int imageID = gdpictureImaging.CreateGdPictureImageFromFile(@"C:\temp\source.png");
// Set the OCR parameters.
gdpictureOCR.SetImage(imageID);
gdpictureOCR.ResourceFolder = @"C:\GdPicture.NET 14\Redist\OCR";
gdpictureOCR.AddLanguage(OCRLanguage.English);
gdpictureOCR.AddLanguage(OCRLanguage.German);
gdpictureOCR.OCRMode = OCRMode.FavorSpeed;
gdpictureOCR.CharacterBlackList = "0123456789";
// Run the OCR process.
string resID = gdpictureOCR.RunOCR();
// Get the result of the OCR process as text.
string content = gdpictureOCR.GetOCRResultText(resID);
// Save the result in a PDF document.
gdpicturePDF.CreateFromText(PdfConformance.PDF_A_4f, 595, 842, 10, 10, 10, 10,
    TextAlignment.TextAlignmentNear, content, 12, "Arial", false, false, true, false);
gdpicturePDF.SaveToFile(@"C:\temp\output.pdf");
gdpictureImaging.ReleaseGdPictureImage(imageID);

```

### VB.NET

```vb

Using gdpicturePDF As GdPicturePDF = New GdPicturePDF()
Using gdpictureImaging As GdPictureImaging = New GdPictureImaging()
Using gdpictureOCR As GdPictureOCR = New GdPictureOCR()
    ' Select the image to process.
    Dim imageID As Integer = gdpictureImaging.CreateGdPictureImageFromFile("C:\temp\source.png")
    ' Set the OCR parameters.
    gdpictureOCR.SetImage(imageID)
    gdpictureOCR.ResourceFolder = "C:\GdPicture.NET 14\Redist\OCR"
    gdpictureOCR.AddLanguage(OCRLanguage.English)
    gdpictureOCR.AddLanguage(OCRLanguage.German)
    gdpictureOCR.OCRMode = OCRMode.FavorSpeed
    gdpictureOCR.CharacterBlackList = "0123456789"
    ' Run the OCR process.
    Dim resID As String = gdpictureOCR.RunOCR()
    ' Get the result of the OCR process as text.
    Dim content As String = gdpictureOCR.GetOCRResultText(resID)
    ' Save the result in a PDF document.
    gdpicturePDF.CreateFromText(PdfConformance.PDF_A_4f, 595, 842, 10, 10, 10, 10,
        TextAlignment.TextAlignmentNear, content, 12, "Arial", False, False, True, False)
    gdpicturePDF.SaveToFile("C:\temp\output.pdf")
    gdpictureImaging.ReleaseGdPictureImage(imageID)
End Using
End Using
End Using

```

#### Used methods and properties

- [`AddLanguage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~AddLanguage.html)

- [`CharacterBlackList`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~CharacterBlackList.html)

- [`CreateFromText`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~CreateFromText.html)

- [`CreateGdPictureImageFromFile`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureImaging~CreateGdPictureImageFromFile.html)

- [`GetOCRResultText`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~GetOCRResultText.html)

- [`OCRMode`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~OCRMode.html)

- [`ReleaseGdPictureImage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureImaging~ReleaseGdPictureImage.html)

- [`ResourceFolder`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~ResourceFolder.html)

- [`RunOCR`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~RunOCR\(\).html)

- [`SaveToFile`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~SaveToFile.html)

- [`SetImage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~SetImage.html)

#### Related topics

- [Load a file](/guides/dotnet/load-a-file.md)

- [Save a file](/guides/dotnet/save-a-file.md)

## Converting multipage TIFF files to searchable PDF/A files

To convert an image file to a searchable PDF/A file, follow the steps outlined below:

1. Create a `GdPicturePDF` object, a `GdPictureImaging` object, and a `GdPictureOCR` object.

2. Select the image by passing its path to the `TiffCreateMultiPageFromFile` method of the `GdPictureImaging` object.

3. Determine the number of pages with the `GetPageCount` method of the `GdPictureImaging` object.

4. Configure the OCR process with the `GdPictureOCR` object in the following way:
   - Set the image with the `SetImage` method.
   - Set the path to the OCR resource folder with the `ResourceFolder` property. The default language resources are located in `GdPicture.NET 14\Redist\OCR`. For more information on adding language resources, see the [language support](https://www.nutrient.io/guides/dotnet/ocr/language-support.md) guide.
   - With the `AddLanguage` method, add the language resources that Nutrient.NET SDK uses to recognize text in the image. This method takes an element of the `OCRLanguage` enum.
   - Optional: Set whether OCR prioritizes recognition accuracy or speed with the `OCRMode` property.
   - Optional: Set the character allowlist with the `CharacterSet` property. When scanning the image, the OCR engine only recognizes the characters included in the allowlist.
   - Optional: Set the character denylist with the `CharacterBlackList` property. When scanning the image, the OCR engine ignores the characters included in the denylist.

5. Create the resulting PDF document with the `NewPDF` method of the `GdPicturePDF` object. The parameter of this method sets the conformance level of the PDF document. This parameter is a member of the `PdfConformance` enumeration. For example, use `PDF_A_4f` to create a document with conformance level PDF/A-4f.

6. Loop through the pages of the image file.

7. For each page, run the OCR process with the `RunOCR` method of the `GdPictureOCR` object, and then add the result to a new page in the PDF.

8. Save the output in a PDF document.

The example below converts a multipage TIFF file to a searchable PDF/A-4f file:

### C#

```csharp

using GdPicturePDF gdpicturePDF = new GdPicturePDF();
using GdPictureImaging gdpictureImaging = new GdPictureImaging();
using GdPictureOCR gdpictureOCR = new GdPictureOCR();
// Select the image to process.
int imageID = gdpictureImaging.TiffCreateMultiPageFromFile(@"C:\temp\source.tif");
// Determine the number of pages.
int pageCount = gdpictureImaging.GetPageCount(imageID);
// Set the OCR parameters.
gdpictureOCR.ResourceFolder = @"C:\GdPicture.NET 14\Redist\OCR";
gdpictureOCR.AddLanguage(OCRLanguage.English);
// Create the resulting PDF document.
gdpicturePDF.NewPDF(PdfConformance.PDF_A_4f);
gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft);
string fontResName = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontCourier);
// Loop through the pages of the image file.
string resID = "page";
string content = null;
for (int i = 1; i <= pageCount; i++)
{
    // Select the current page and set up the image for OCR.
    gdpictureImaging.TiffSelectPage(imageID, i);
    gdpictureOCR.SetImage(imageID);
    // Run the OCR process on the current page.
    gdpictureOCR.RunOCR(resID);
    // Get the result.
    content = gdpictureOCR.GetOCRResultText(resID);
    // Add the result to a new page in the PDF.
    gdpicturePDF.NewPage(PdfPageSizes.PdfPageSizeA4);
    gdpicturePDF.DrawText(fontResName, 10, 10, content);

    // Release the previous OCR result. This improves memory management.
    gdpictureOCR.ReleaseOCRResult(resID);
}
// Save the resulting PDF document.
gdpicturePDF.SaveToFile(@"C:\temp\output.pdf");
gdpicturePDF.CloseDocument();
gdpictureImaging.ReleaseGdPictureImage(imageID);

```

### VB.NET

```vb

Using gdpicturePDF As GdPicturePDF = New GdPicturePDF()
Using gdpictureImaging As GdPictureImaging = New GdPictureImaging()
Using gdpictureOCR As GdPictureOCR = New GdPictureOCR()
    ' Select the image to process.
    Dim imageID As Integer = gdpictureImaging.TiffCreateMultiPageFromFile("C:\temp\source.tif")
    ' Determine the number of pages.
    Dim pageCount = gdpictureImaging.GetPageCount(imageID)
    ' Set the OCR parameters.
    gdpictureOCR.ResourceFolder = "C:\GdPicture.NET 14\Redist\OCR"
    gdpictureOCR.AddLanguage(OCRLanguage.English)
    ' Create the resulting PDF document.
    gdpicturePDF.NewPDF(PdfConformance.PDF_A_4f)
    gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft)
    Dim fontResName As String = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontCourier)
    ' Loop through the pages of the image file.
    Dim resID = "page"
    Dim content As String = Nothing
    For i = 1 To pageCount
        ' Select the current page and set up the image for OCR.
        gdpictureImaging.TiffSelectPage(imageID, i)
        gdpictureOCR.SetImage(imageID)
        ' Run the OCR process on the current page.
        gdpictureOCR.RunOCR(resID)
        ' Get the result.
        content = gdpictureOCR.GetOCRResultText(resID)
        ' Add the result to a new page in the PDF.
        gdpicturePDF.NewPage(PdfPageSizes.PdfPageSizeA4)
        gdpicturePDF.DrawText(fontResName, 10, 10, content)
        ' Release the previous OCR result. This improves memory management.
        gdpictureOCR.ReleaseOCRResult(resID)
    Next
    ' Save the resulting PDF document.
    gdpicturePDF.SaveToFile("C:\temp\output.pdf")
    gdpicturePDF.CloseDocument()
    gdpictureImaging.ReleaseGdPictureImage(imageID)
End Using
End Using
End Using

```

#### Used methods and properties

- [`AddLanguage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~AddLanguage.html)

- [`AddStandardFont`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~AddStandardFont.html)

- [`CloseDocument`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~CloseDocument.html)

- [`DrawText`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~DrawText.html)

- [`GetOCRResultText`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~GetOCRResultText.html)

- [`GetPageCount`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureImaging~GetPageCount.html)

- [`NewPage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~NewPage.html)

- [`NewPDF`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~NewPDF.html)

- [`ReleaseGdPictureImage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureImaging~ReleaseGdPictureImage.html)

- [`ReleaseOCRResult`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~ReleaseOCRResult.html)

- [`ResourceFolder`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~ResourceFolder.html)

- [`RunOCR`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~RunOCR\(\).html)

- [`SaveToFile`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~SaveToFile.html)

- [`SetImage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureOCR~SetImage.html)

- [`SetOrigin`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPicturePDF~SetOrigin.html)

- [`TiffCreateMultiPageFromFile`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureImaging~TiffCreateMultiPageFromFile.html)

- [`TiffSelectPage`](/api/gdpicture/GdPicture.NET.14~GdPicture14.GdPictureImaging~TiffSelectPage.html)

#### Related topics

- [Load a file](/guides/dotnet/load-a-file.md)

- [Save a file](/guides/dotnet/save-a-file.md)
---

## Related pages

- [OCR PDF in C#](/guides/dotnet/ocr/usage/pdf-to-searchable-pdf.md)
- [C# barcode recognition](/guides/dotnet/ocr/usage/barcode-recognition.md)
- [C# OCR image to text](/guides/dotnet/ocr/usage/image-to-searchable-pdf.md)
- [C# OCR scanning to searchable PDFs](/guides/dotnet/ocr/usage/ocr-scan.md)