ByteScout PDF Extractor SDK – C# – .NET Core 2.0 – OCR (Optical Character Recognition)

ByteScout PDF Extractor SDK – C# – .NET Core 2.0 – OCR (Optical Character Recognition)

Program.cs

using System.Diagnostics;
using Bytescout.PDFExtractor;

// This example demonstrates the use of Optical Character Recognition (OCR) to extract text 
// from scanned PDF documents and raster images.

// To make OCR work you should add the following references to your project:
// 'Bytescout.PDFExtractor.dll', 'Bytescout.PDFExtractor.OCRExtension.dll'.

namespace OCRExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create Bytescout.PDFExtractor.TextExtractor instance
            TextExtractor extractor = new TextExtractor();
            extractor.RegistrationName = "demo";
            extractor.RegistrationKey = "demo";

            // Load sample PDF document
            extractor.LoadDocumentFromFile(@".\sample_ocr.pdf");

            // Enable Optical Character Recognition (OCR)
            // in .Auto mode (SDK automatically checks if needs to use OCR or not)
            extractor.OCRMode = OCRMode.Auto;

            // Set the location of "tessdata" folder containing language data files
            extractor.OCRLanguageDataFolder = @"c:\Program Files\Bytescout PDF Extractor SDK\Redistributable\net2.00\tessdata\";

            // Set OCR language
            extractor.OCRLanguage = "eng"; // "eng" for english, "deu" for German, "fra" for French, "spa" for Spanish etc - according to files in /tessdata
                                           // Find more language files at https://github.com/tesseract-ocr/tessdata/tree/3.04.00

            // Set PDF document rendering resolution
            extractor.OCRResolution = 300;


            // You can also apply various preprocessing filters
            // to improve the recognition on low-quality scans.

            // Automatically deskew skewed scans
            //extractor.OCRImagePreprocessingFilters.AddDeskew();

            // Remove vertical or horizontal lines (sometimes helps to avoid OCR engine's page segmentation errors)
            //extractor.OCRImagePreprocessingFilters.AddVerticalLinesRemover();
            //extractor.OCRImagePreprocessingFilters.AddHorizontalLinesRemover();

            // Repair broken letters
            //extractor.OCRImagePreprocessingFilters.AddDilate();

            // Remove noise
            //extractor.OCRImagePreprocessingFilters.AddMedian();

            // Apply Gamma Correction
            //extractor.OCRImagePreprocessingFilters.AddGammaCorrection();

            // Add Contrast
            //extractor.OCRImagePreprocessingFilters.AddContrast(20);


            // (!) You can use new OCRAnalyser class to find an optimal set of image preprocessing 
            // filters for your specific document.
            // See "OCR Analyser" example.


            // Save extracted text to file
            extractor.SaveTextToFile("output.txt");

            // Cleanup
            extractor.Dispose();

            // Open output file in default associated application
            Process.Start(new ProcessStartInfo("output.txt") { UseShellExecute = true });
        }
    }
}

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