---
title: "Read PDF and image: Read text from PDF and images in C# | Nutrient .NET SDK"
canonical_url: "https://www.nutrient.io/guides/dotnet/extraction/text/read/"
md_url: "https://www.nutrient.io/guides/dotnet/extraction/text/read.md"
last_updated: "2026-05-21T17:12:02.203Z"
description: "Learn how to read text from PDF documents and images programmatically in C# using Nutrient .NET SDK. Implement text extraction capabilities in your applications."
---

# Read text from PDFs and images in C#

This guide explains how to read text from a PDF or image file. Sometimes, text is stored in a PDF or an image in a way that makes it so you cannot search or copy it. Nutrient.NET SDK’s (formerly GdPicture.NET) optical character recognition (OCR) engine enables you to recognize text and save it in a separate file where you can both search and copy and paste the text.

## Reading text from a PDF

To read text from a PDF, follow the steps below:

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

2. Select the source document by passing its path to the `LoadFromFile` method of the `GdPicturePDF` object.

3. 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 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 doesn’t recognize the characters included in the denylist.

4. Create an empty string where you’ll save the output.

5. Determine the number of pages with the `GetPageCount` method of the `GdPicturePDF` object and loop through them.

6. Render each page to a 300 dots-per-inch (DPI) image with the `RenderPageToGdPictureImageEx` method of the `GdPicturePDF` object.

7. Pass the image to the `GdPictureOCR` object with the `SetImage` method of the `GdPictureOCR` object.

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

9. Get the result of the OCR process as text with the `GetOCRResultText` method of the `GdPictureOCR` object, and save it in the output string.

10. Release the image with the `DisposeImage` method of the `GdPictureDocumentUtilities` class, and release the OCR result with the `ReleaseOCRResult` method of the `GdPictureOCR` object.

11. After reading all the pages, save the output in a new text file with the standard `System.IO.StreamWriter` class.

12. Release unnecessary resources.

The example below reads text from a PDF and saves the output in a TXT file:

### C#

```csharp

using GdPicturePDF gdpicturePDF = new GdPicturePDF();
using GdPictureOCR gdpictureOCR = new GdPictureOCR();
// Select the source document.
gdpicturePDF.LoadFromFile(@"C:\temp\source.pdf");
// Configure the OCR process.
gdpictureOCR.ResourceFolder = @"C:\GdPicture.NET 14\Redist\OCR";
gdpictureOCR.AddLanguage(OCRLanguage.English);
// Create an empty string where you'll save the output.
string outputText = "";
// Determine the number of pages and loop through them.
int pageCount = gdpicturePDF.GetPageCount();
for (int page = 1; page <= pageCount; page++)
{
    gdpicturePDF.SelectPage(page);
    // Render the page to a 300 DPI image.
    int imageId = gdpicturePDF.RenderPageToGdPictureImageEx(300, true);
    // Pass the image to the `GdPictureOCR` object.
    gdpictureOCR.SetImage(imageId);
    // Run the OCR process.
    string resultId = gdpictureOCR.RunOCR();
    // Get the result of the OCR process as text.
    outputText += gdpictureOCR.GetOCRResultText(resultId);
    // Release the image and the OCR result.
    GdPictureDocumentUtilities.DisposeImage(imageId);
    gdpictureOCR.ReleaseOCRResult(resultId);
}
// Save the output in a new text file.
System.IO.StreamWriter outputFile = new System.IO.StreamWriter(@"C:\temp\output.txt");
outputFile.WriteLine(outputText);
outputFile.Close();
// Release unnecessary resources.
gdpicturePDF.CloseDocument();

```

### VB.NET

```vb

Using gdpicturePDF As GdPicturePDF = New GdPicturePDF()
Using gdpictureOCR As GdPictureOCR = New GdPictureOCR()
    ' Select the source document.
    gdpicturePDF.LoadFromFile("C:\temp\source.pdf")
    ' Configure the OCR process.
    gdpictureOCR.ResourceFolder = "C:\GdPicture.NET 14\Redist\OCR"
    gdpictureOCR.AddLanguage(OCRLanguage.English)
    ' Create an empty string where you'll save the output.
    Dim outputText = ""
    ' Determine the number of pages and loop through them.
    Dim pageCount As Integer = gdpicturePDF.GetPageCount()
    For page = 1 To pageCount
        gdpicturePDF.SelectPage(page)
        ' Render the page to a 300 DPI image.
        Dim imageId As Integer = gdpicturePDF.RenderPageToGdPictureImageEx(300, True)
        ' Pass the image to the `GdPictureOCR` object.
        gdpictureOCR.SetImage(imageId)
        ' Run the OCR process.
        Dim resultId As String = gdpictureOCR.RunOCR()
        ' Get the result of the OCR process as text.
        outputText += gdpictureOCR.GetOCRResultText(resultId)
        ' Release the image and the OCR result.
        GdPictureDocumentUtilities.DisposeImage(imageId)
        gdpictureOCR.ReleaseOCRResult(resultId)
    Next
    ' Save the output in a new text file.
    Dim outputFile As StreamWriter = New StreamWriter("C:\temp\output.txt")
    outputFile.WriteLine(outputText)
    outputFile.Close()
    ' Release unnecessary resources.
    gdpicturePDF.CloseDocument()
End Using
End Using

```

#### Used methods and properties

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

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

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

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

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

- [`DisposeImage`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureDocumentUtilities~DisposeImage.html)

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

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

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

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

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

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

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

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

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

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

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

#### Related topics

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

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

## Reading text from an image

This section explains how to read text from simple, single-page image files. For more information on reading multipage image files, see [Reading Text from Multipage TIFF Files](#reading-text-from-multipage-tiff-files).

To read text from an image file, follow the steps 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 doesn’t recognize 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. Save the output in a new text file with the standard `System.IO.StreamWriter` class.

7. Release unnecessary resources.

The example below reads text from an image file and saves the output in a TXT file:

### C#

```csharp

using GdPictureImaging gdpictureImaging = new GdPictureImaging();
using GdPictureOCR gdpictureOCR = new GdPictureOCR();
// Select the image to read.
int imageId = gdpictureImaging.CreateGdPictureImageFromFile(@"C:\temp\source.png");
// Configure the OCR parameters.
gdpictureOCR.SetImage(imageId);
gdpictureOCR.ResourceFolder = @"C:\GdPicture.NET 14\Redist\OCR";
gdpictureOCR.AddLanguage(OCRLanguage.English);
// Run the OCR process.
string resultId = gdpictureOCR.RunOCR();
// Get the result of the OCR process as text.
string outputText = gdpictureOCR.GetOCRResultText(resultId);
// Save the output in a new text file.
System.IO.StreamWriter outputFile = new System.IO.StreamWriter(@"/Users/manototh/Documents/windows/temp/output.txt");
outputFile.WriteLine(outputText);
outputFile.Close();
// Release unnecessary resources.
gdpictureImaging.ReleaseGdPictureImage(imageId);

```

### VB.NET

```vb

Using gdpictureImaging As GdPictureImaging = New GdPictureImaging()
Using gdpictureOCR As GdPictureOCR = New GdPictureOCR()
    ' Select the image to read.
    Dim imageId As Integer = gdpictureImaging.CreateGdPictureImageFromFile("C:\temp\source.png")
    ' Configure the OCR parameters.
    gdpictureOCR.SetImage(imageId)
    gdpictureOCR.ResourceFolder = "C:\GdPicture.NET 14\Redist\OCR"
    gdpictureOCR.AddLanguage(OCRLanguage.English)
    ' Run the OCR process.
    Dim resultId As String = gdpictureOCR.RunOCR()
    ' Get the result of the OCR process as text.
    Dim outputText As String = gdpictureOCR.GetOCRResultText(resultId)
    ' Save the output in a new text file.
    Dim outputFile As StreamWriter = New StreamWriter("/Users/manototh/Documents/windows/temp/output.txt")
    outputFile.WriteLine(outputText)
    outputFile.Close()
    ' Release unnecessary resources.
    gdpictureImaging.ReleaseGdPictureImage(imageId)
End Using
End Using

```

### Alternative minimal pipeline

If you want a shorter single-image OCR flow, you can use this focused snippet:

```csharp

using GdPictureImaging imaging = new GdPictureImaging();
using GdPictureOCR ocr = new GdPictureOCR();

int imageId = imaging.CreateGdPictureImageFromFile(@"input.png");
ocr.SetImage(imageId);

string ocrResultId = ocr.RunOCR(OCRSpecialContext.None);
string result = ocr.GetOCRResultText(ocrResultId);

File.WriteAllText(@"output.txt", result);

```

#### Used methods and properties

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

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

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

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

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

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

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

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

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

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

#### Related topics

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

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

## Reading text from multipage TIFF files

To read text from a multipage TIFF file, follow the steps below:

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

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

3. 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 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 doesn’t recognize the characters included in the denylist.

4. Create an empty string where you’ll save the output.

5. Determine the number of pages with the `GetPageCount` method of the `GdPictureImaging` object and loop through them.

6. Select a page with the `TiffSelectPage` method of the `GdPictureImaging` object.

7. Pass the page to the `GdPictureOCR` object with the `SetImage` method of the `GdPictureOCR` object.

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

9. Get the result of the OCR process as text with the `GetOCRResultText` method of the `GdPictureOCR` object, and save it in the output string.

10. Release the OCR result with the `ReleaseOCRResult` method of the `GdPictureOCR` object.

11. After reading all the pages, save the output in a new text file with the standard `System.IO.StreamWriter` class.

12. Release unnecessary resources.

The example below reads text from a multipage TIFF file and saves the output in a TXT file:

### C#

```csharp

using GdPictureImaging gdpictureImaging = new GdPictureImaging();
using GdPictureOCR gdpictureOCR = new GdPictureOCR();
// Select the image to read.
int imageId = gdpictureImaging.TiffCreateMultiPageFromFile(@"C:\temp\source.tif");
// Configure the OCR parameters.
gdpictureOCR.ResourceFolder = @"C:\GdPicture.NET 14\Redist\OCR";
gdpictureOCR.AddLanguage(OCRLanguage.English);
// Create an empty string where you'll save the output.
string outputText = "";
// Determine the number of pages and loop through them.
int pageCount = gdpictureImaging.GetPageCount(imageId);
for (int page = 1; page <= pageCount; page++)
{
    // Select a page and pass it to the `GdPictureOCR` object.
    gdpictureImaging.TiffSelectPage(imageId, page);
    gdpictureOCR.SetImage(imageId);
    // Run the OCR process.
    string resultId = gdpictureOCR.RunOCR();
    // Get the result of the OCR process as text.
    outputText += gdpictureOCR.GetOCRResultText(resultId);
    // Release the OCR result.
    gdpictureOCR.ReleaseOCRResult(resultId);
}
// Save the output in a new text file.
System.IO.StreamWriter outputFile = new System.IO.StreamWriter(@"C:\temp\output.txt");
outputFile.WriteLine(outputText);
outputFile.Close();
// Release unnecessary resources.
gdpictureImaging.ReleaseGdPictureImage(imageId);

```

### VB.NET

```vb

Using gdpictureImaging As GdPictureImaging = New GdPictureImaging()
Using gdpictureOCR As GdPictureOCR = New GdPictureOCR()
    ' Select the image to read.
    Dim imageId As Integer = gdpictureImaging.TiffCreateMultiPageFromFile("C:\temp\source.tif")
    ' Configure the OCR parameters.
    gdpictureOCR.ResourceFolder = "C:\GdPicture.NET 14\Redist\OCR"
    gdpictureOCR.AddLanguage(OCRLanguage.English)
    ' Create an empty string where you'll save the output.
    Dim outputText = ""
    ' Determine the number of pages and loop through them.
    Dim pageCount As Integer = gdpictureImaging.GetPageCount(imageId)
    For page = 1 To pageCount
        ' Select a page and pass it to the `GdPictureOCR` object.
        gdpictureImaging.TiffSelectPage(imageId, page)
        gdpictureOCR.SetImage(imageId)
        ' Run the OCR process.
        Dim resultId As String = gdpictureOCR.RunOCR()
        ' Get the result of the OCR process as text.
        outputText += gdpictureOCR.GetOCRResultText(resultId)
        ' Release the OCR result.
        gdpictureOCR.ReleaseOCRResult(resultId)
    Next
    ' Save the output in a new text file.
    Dim outputFile As StreamWriter = New StreamWriter("C:\temp\output.txt")
    outputFile.WriteLine(outputText)
    outputFile.Close()
    ' Release unnecessary resources.
    gdpictureImaging.ReleaseGdPictureImage(imageId)
End Using
End Using

```

#### Used methods and properties

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

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

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

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

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

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

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

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

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

- [`TiffSelectPage`](/api/gdpicture/GdPicture.NET.14.API~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

- [Extract text from PDFs using C#](/guides/dotnet/extraction/text/extract.md)