C# OCR (How to Read a single character from image)

Tesseract and GOCR are not easy to use and not so good; Office is proprietary, not always available.

Thsre is C# binding for Tesseract called Tessnet: http://www.pixel-technology.com/freeware/tessnet2/[^].

There are some good works on CodeProjects. I think they are better but need to be completed. Basic and most difficult work is done. As you mentioned "single character", one of them must be ideal for you (I tried them out). See: Neural Network OCR[^] (this one is one of the best), Creating Optical Character Recognition (OCR) applications using Neural Networks[^], OCR Line Detection[^], Unicode Optical Character Recognition[^] (this one is one of the best).

Good luck,

—SA

I am useing the MODI (Office OCR) to do this. It is working like a charm for words, sentences, numbers and mixes of both. However - It fails if the image contains only one single character.
I have no idea why i fails, but since this is what you wanted to do, you should probably go for one of the other ocr solutions.

Is there anybody who knows why it fails with only one letter?

Here is my code:

// Load Image from File
Bitmap BWImage = new Bitmap(fileName);
// Lock destination bitmap in memory
System.Drawing.Imaging.BitmapData BWLockImage = BWImage.LockBits(new Rectangle(0, 0, BWImage.Width, BWImage.Height), System.Drawing.Imaging.ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed);

// Copy image data to binary array
int imageSize = BWLockImage.Stride * BWLockImage.Height;
byte[] BWImageBuffer = new byte[imageSize];
Marshal.Copy(BWLockImage.Scan0, BWImageBuffer, 0, imageSize);
DoOCR(BWLockImage, BWImageBuffer, tmpPosRect, false);



// Do the OCR with this function
public string DoOCR(System.Drawing.Imaging.BitmapData BWLockImage, byte[] BWImageBuffer, Rectangle iAusschnitt, bool isNumber)
{
    Bitmap tmpImage = Bildausschnitt1bpp(BWLockImage, BWImageBuffer, iAusschnitt);
    string file = Path.GetTempFileName();
    string tmpResult = "";
    try
    {
        tmpImage.Save(file, ImageFormat.Tiff);
        _MODIDocument.Create(file);
        // Modi parameter erstellen
        _MODIDocument.OCR(MODI.MiLANGUAGES.miLANG_ENGLISH, false, false);

        MODI.IImage myImage = (MODI.IImage)_MODIDocument.Images[0]; //first page in file
        MODI.ILayout myLayout = (MODI.ILayout)myImage.Layout;
        tmpResult = myLayout.Text;
    }
    catch
    {
        if (_MODIDocument != null)
        {
            _MODIDocument.Close(false); //Closes the document and deallocates the memory.
            _MODIDocument = null;
        }
        // Bild freigeben
        tmpImage.Dispose();
        tmpImage = null;
        // Garbage Collector ausführen
        GC.Collect();
        // Bilddatei löschen
        File.Delete(file);
    }
    return tmpResult;
}