---
title: "C# .NET OCR image to text: Fast and accurate extraction | Nutrient .NET SDK"
canonical_url: "https://www.nutrient.io/guides/dotnet/ocr/usage/image-to-searchable-pdf/"
md_url: "https://www.nutrient.io/guides/dotnet/ocr/usage/image-to-searchable-pdf.md"
last_updated: "2026-05-21T17:12:02.207Z"
description: "Learn how to perform optical character recognition (OCR) to extract text from images and create searchable PDFs using Nutrient .NET SDK. Improve document accessibility today!"
---

# C# OCR image to text

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

## Converting an image to PDF and applying OCR

In addition to the `GdPictureOCR`-based approach below, you can use a streamlined workflow that first converts the image to PDF and then applies OCR directly on PDF pages.

```csharp

using GdPicturePDF pdf = new GdPicturePDF();
using GdPictureDocumentConverter converter = new GdPictureDocumentConverter();

converter.LoadFromFile(@"input.png");
converter.SaveAsPDF(@"output_intermediary.pdf");

pdf.LoadFromFile(@"output_intermediary.pdf", true);
pdf.OcrPages("*", 0, "eng", "", "", 200);
pdf.SaveToFile(@"output_with_ocr.pdf");

```

This method is useful when your workflow already centers around PDF processing and you want to make the entire document searchable in one step.

## Converting image files to searchable PDFs

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 PDFs](#converting-multipage-tiff-files-to-searchable-pdfs).

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

1. Create a `GdPicturePDF` object, 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. The first parameter sets the conformance level of the PDF document. This parameter is a member of the `PdfConformance` enumeration. For example, use `PDF` to create a common PDF document.

7. Save the output in a PDF document.

The example below converts an image file to a searchable PDF by 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, 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, 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. 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, 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, 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 PDFs

To convert an image file to a searchable PDF, follow the steps 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 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 doesn’t recognize 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` to create a common PDF document.

6. Loop through 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:

### 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);
gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft);
string fontResName = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontCourier);
// Loop through 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 = 0
    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)
    gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft)
    Dim fontResName As String = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontCourier)
    ' Loop through 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

- [C# barcode recognition](/guides/dotnet/ocr/usage/barcode-recognition.md)
- [C# OCR scanning to searchable PDFs](/guides/dotnet/ocr/usage/ocr-scan.md)
- [OCR PDF in C#](/guides/dotnet/ocr/usage/pdf-to-searchable-pdf.md)
- [Convert images into searchable PDF/A files in C#](/guides/dotnet/ocr/usage/pdfa-archiving.md)