Programmatically recognize text from scans in a PDF File [closed]

Answer 1

Based on Mark Brackett's answer, I created a Nuget package to wrap pdftotext.

It's open source, targeting .net standard 1.6 and .net framework 4.5.

Usage:

using XpdfNet;

var pdfHelper = new XpdfHelper();

string content = pdfHelper.ToText("./pathToFile.pdf");

Answer 2

I have posted about parsing pdf's in one of my blogs. Hit this link:

http://devpinoy.org/blogs/marl/archive/2008/03/04/pdf-to-text-using-open-source-library-pdfbox-another-sample-for-grade-1-pupils.aspx

Edit: Link no long works. Below quoted from http://web.archive.org/web/20130507084207/http://devpinoy.org/blogs/marl/archive/2008/03/04/pdf-to-text-using-open-source-library-pdfbox-another-sample-for-grade-1-pupils.aspx

Well, the following is based on popular examples available on the web. What this does is "read" the pdf file and output it as a text in the rich text box control in the form. The PDFBox for .NET library can be downloaded from sourceforge.

You need to add reference to IKVM.GNU.Classpath & PDFBox-0.7.3. And also, FontBox-0.1.0-dev.dll and PDFBox-0.7.3.dll need to be added on the bin folder of your application. For some reason I can't recall (maybe it's from one of the tutorials), I also added to the bin IKVM.GNU.Classpath.dll.

On the side note, just got my copy of "Head First C#" (on Keith's suggestion) from Amazon. The book is cool! It is really written for beginners. This edition covers VS2008 and the framework 3.5.

Here you go...

/* Marlon Ribunal
 * Convert PDF To Text
 * *******************/

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Printing;
using System.IO;
using System.Text;
using System.ComponentModel.Design;
using System.ComponentModel;
using org.pdfbox.pdmodel;
using org.pdfbox.util;

namespace MarlonRibunal.iPdfToText
{
    public partial class MainForm : Form
    {
        public MainForm()
        {
            InitializeComponent(); 
        }

        void Button1Click(object sender, EventArgs e)    
        {    
            PDDocument doc = PDDocument.load("C:\\pdftoText\\myPdfTest.pdf");
            PDFTextStripper stripper = new PDFTextStripper();
            richTextBox1.Text=(stripper.getText(doc));
        }

     }
}

Answer 3

If the PDF is a scans of printed text, it will be hard (involves image processing, character recognizing etc.) to do it yourself. PDF will generally store the scanned documents as JPEGs internally. You are better of using a third party tool (OCR tool) that does this.

Answer 4

You can't extract scanned text from a PDF. You need OCR software. The good news is there are a few open source applications you can try and the OCR route will most likely be easier than using a PDF library to extract text. Check out Tesseract and GOCR.