How to Use Tessnet2 Library

• Download source code

This article has the goal to show how to use the Tessnet2 library.

Tessnet2 is a .NET 2.0 Open Source OCR assembly using Tesseract engine. Download binary here.

Another important thing for Tessnet2 work is get the languages packages, get it here for the languages you want. For the sample, we are using the English language.

Let’s start the sample.

Create one console application:

Then copy the folder with binaries and languages packages to the same folder.
Note: Don't forget to unzip the languages packages until you have the tessdata folder with eng.DangAmbigs, eng.freq-dawg, eng.inttemp, eng.normproto, eng.pffmtable, eng.unicharset, eng.user-words and eng.word-dawg files.

The aspect should be something like:

Now add the Tessnet2 reference to the project, do a right click in References > Add References > Browse> Select the folder with C:\OCRTest\tessnet2\Release64\tessnet2_64.dll and click Ok.

After add the reference for System.Drawing:

Now, we need to configure the project to compile in x64, for it Right Click in project> Properties>Build> Platform target.

In Program.cs, add the following code:

static void Main(string[] args)
        {
            try
            {
                var image = new Bitmap(@"C:\OCRTest\number.jpg");
                var ocr = new Tesseract();
                ocr.SetVariable("tessedit_char_whitelist", "0123456789"); // If digit only
                //@"C:\OCRTest\tessdata" contains 
                //the language package, without this the method crash and app breaks
                ocr.Init(@"C:\OCRTest\tessdata", "eng", true); 
                var result = ocr.DoOCR(image, Rectangle.Empty);
                foreach (Word word in result)
                    Console.WriteLine("{0} : {1}", word.Confidence, word.Text);

                Console.ReadLine();
            }
            catch (Exception exception)
            {

            }
        }

and run the application, this gives an error:

To solve this, go to directory and change the App.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>
</configuration>

For the test:

The result is:

You can download the source code here.