Which library to use to extract text from images?

Question

I am writing a program that when given an image of a low level math problem (e.g. 98*13) should be able to output the answer. The numbers would be black, and the background white. Not a captcha, just an image of a math problem.

The math problems would only have two numbers and one operator, and that operator would only be +, -, *, or /.

Obviously, I know how to do the calculating ;) I'm just not sure how to go about getting the text from the image.

A free library would be ideal... although If I have to write the code myself I could probably manage.

Answer 1

For extract words from image, I use the most accurate open source OCR engine: Tesseract. Available here or directly in your packages NuGet.

And this is my function in C#, which extract words from image passed in sourceFilePath. Set EngineMode to TesseractAndCube; it detect more word than the other options.

var path = "YourSolutionDirectoryPath";
using (var engine = new TesseractEngine(path + Path.DirectorySeparatorChar + "tessdata", "fra", EngineMode.TesseractAndCube))
{
    using (var img = Pix.LoadFromFile(sourceFilePath))
    {
        using (var page = engine.Process(img))
        {
            var text = page.GetText();
            // text variable contains a string with all words found
        }
    }
}

I hope that helps.