PDF .Net

using SautinSoft.Pdf;
    using SautinSoft.Pdf.Content;
    using SautinSoft.Pdf.Objects;
    using System;
    using Tesseract;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;

    namespace OCR
    {
        class OCR
        {
            static void Main()
            {
                try
                {
                    string tesseractLanguages = "eng";
                    string tesseractData = Path.GetFullPath(@".\tessdata\");
                    string tempFile = Path.Combine(tesseractData, Path.GetRandomFileName());
                    PdfDocument pdfDocument = PdfDocument.Load(@"..\..\..\Scanned.pdf");
                    PdfFormattedText text = new PdfFormattedText();

                    using (Tesseract.TesseractEngine engine = new Tesseract.TesseractEngine(tesseractData, tesseractLanguages, Tesseract.EngineMode.Default))
                    {
                        foreach (var pdfPage in pdfDocument.Pages)
                        {
                                var collection = pdfPage.Content.Elements.All().OfType〈PdfImageContent>().ToList();
                                for (int i = 0; i 〈 collection.Count(); i++)
                            {
                                engine.DefaultPageSegMode = Tesseract.PageSegMode.Auto;
                                using (MemoryStream ms = new MemoryStream())
                                {
                                    collection[i].Save(ms, new ImageSaveOptions());

                                    byte[] imgBytes = ms.ToArray();
                                    using (Tesseract.Pix img = Tesseract.Pix.LoadFromMemory(imgBytes))
                                    {
                                        using (var page = engine.Process(img, "Serachablepdf"))
                                        {
                                            var st = page.GetText();
                                            double scale = Math.Min(collection[i].Bounds.Width / page.RegionOfInterest.Width, collection[i].Bounds.Height / page.RegionOfInterest.Height);

                                            using (var iter = page.GetIterator())
                                            {
                                                iter.Begin();

                                                do
                                                {
                                                    do
                                                    {
                                                        do
                                                        {
                                                            do
                                                            {
                                                                iter.TryGetBoundingBox(PageIteratorLevel.Word, out Rect liRect);
                                                                text.FontSize = liRect.Height * scale;
                                                                text.Opacity = 0;
                                                                text.Append(iter.GetText(PageIteratorLevel.Word));
                                                                pdfPage.Content.DrawText(text, new PdfPoint(collection[i].Bounds.Left + liRect.X1 * scale, collection[i].Bounds.Top - liRect.Y1 * scale - text.Height));
                                                                text.Clear();
                                                            } while (iter.Next(PageIteratorLevel.TextLine, PageIteratorLevel.Word));
                                                        } while (iter.Next(PageIteratorLevel.Para, PageIteratorLevel.TextLine));
                                                    } while (iter.Next(PageIteratorLevel.Block, PageIteratorLevel.Para));
                                                } while (iter.Next(PageIteratorLevel.Block));
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                    pdfDocument.Save(@"Result.pdf");
                    System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo("Result.pdf") { UseShellExecute = true });
                }
                catch (Exception e)
                {
                    Console.WriteLine();
                    Console.WriteLine("Please be sure that you have Language data files (*.traineddata) in your folder \"tessdata\"");
                    Console.WriteLine("The Language data files can be download from here: https://github.com/tesseract-ocr/tessdata_fast");
                    Console.ReadKey();
                    throw new Exception("Error Tesseract: " + e.Message);
                }
                finally
                {

                }
            }
        }
    }