Scanned PDF to Text
How to Convert Scanned PDFs into Searchable Text Documents in .NET

How to Convert Scanned PDFs into Searchable Text Documents in .NET

Scanned PDFs are typically non-editable, image-based files, which makes it difficult to extract text from them. However, with Aspose.OCR for .NET, you can quickly transform these scanned PDFs into editable, searchable text documents that make data retrieval and document management much easier.

Why Should You Convert Scanned PDFs to Searchable Text?

  1. Enhanced Accessibility:
    • Scanned PDFs can be converted into text that is searchable and editable, allowing better accessibility to the content.
  2. Data Organization:
    • Once converted, the text can be organized, manipulated, and reused in various formats like Word, Excel, or plain text.
  3. Content Retention:
    • Aspose.OCR ensures that the original images and layout are preserved while the text is extracted, giving you both content and context.

Prerequisites: Getting Ready for Scanned PDF Conversion

Before you begin the process of extracting text from scanned PDFs, ensure the following:

  1. Install Aspose.OCR for .NET:
    • Install the necessary library using NuGet with the command:
      dotnet add package Aspose.OCR
  2. License Configuration:
    • Obtain and configure a metered license using the SetMeteredKey() method to unlock all features.
  3. Prepare Your Scanned PDFs:
    • Ensure that your scanned PDFs are in good quality (300 DPI or higher) for the best OCR results.

Step-by-Step Guide to Convert Scanned PDFs to Text

Step 1: Configure Your License

Begin by configuring your Aspose.OCR license to ensure full access to the features.

using Aspose.OCR;

Metered license = new Metered();
license.SetMeteredKey("<your public key>", "<your private key>");
Console.WriteLine("Metered license configured successfully.");

Step 2: Load the Scanned PDF into the OCR Input Object

Load the scanned PDF file into the OCR engine for text recognition.

OcrInput input = new OcrInput(Aspose.OCR.InputType.PDF);
input.Add("scanned_document.pdf", 0, 3);  // Specify pages to process (first 3 pages)
Console.WriteLine("Scanned PDF loaded successfully.");

Step 3: Configure the OCR Engine for Recognition

Set up the OCR engine to optimize text extraction from the scanned PDF.

Aspose.OCR.AsposeOcr recognitionEngine = new Aspose.OCR.AsposeOcr();
RecognitionSettings settings = new RecognitionSettings();
settings.Language = Aspose.OCR.Language.Latin;  // Specify OCR language (use Latin for English)
Console.WriteLine("OCR settings configured.");

Step 4: Extract and Save the Recognized Text

Process the scanned PDF to extract the text and output it to a file.

List<Aspose.OCR.RecognitionResult> results = recognitionEngine.Recognize(input, settings);
Console.WriteLine("Text extraction successful.");

// Output the recognized text to a file
results[0].Save("recognized_text.txt", Aspose.OCR.SaveFormat.Text);
Console.WriteLine("Recognized text saved to recognized_text.txt.");

Step 5: Test the Recognized Text

After the extraction, verify the accuracy of the text recognition by checking the output file or displaying it on the console.

Common Issues and Fixes

1. Poor OCR Accuracy

  • Solution: Make sure the scanned PDF quality is high (300 DPI or more) for better recognition accuracy.

2. Incorrect Language Recognition

  • Solution: Explicitly specify the language setting in RecognitionSettings for better results, especially for non-Latin characters.

3. Slow Performance for Large Files

  • Solution: Process large PDFs in chunks or optimize memory usage to speed up the OCR process.
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