Tuesday, January 22, 2013

Simple OCR in Visual Basic 6


Do you want to make an application that has OCR ability within vb6?  Well, I did and I almost gave up because I could not find an OCR ActiveX.  Then I found Tesseract.
Although it is not an ActiveX and seems only usable for Visual Basic 2008 or higher, but we can actually make use of its capability.

Download tesseract from here and install. Then insert this line in your VB code:

Shell "tesseract <image files> <output file>"

for example:

Shell "tesseract c:\cap.bmp c:\output", vbHide

Tesseract will convert the image ("cap.bmp") into text and save it into a TXT file ("output.txt").  Then, all you have to do is read the output file.

Here is a short demo video:


The VB6 Project can be downloaded here.

UPDATE
Shelling tesseract in Windows7 doesn't work.  The quick solution is to create *.bat file, and shell it.

You can create *.bat file in notepad with following line:

tesseract c:\cap.bmp c:\output

 For example, if you create "ocr.bat", the shell command in vb6 will look like:

 Shell "c:\ocr.bat", vbHide
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11 comments:

  1. ImmanuelMarch 27, 2013 at 7:03 AM

    How do I get it to work? I mean I have tesseract installed, I downloaded your project, it runs fine upon F5, but it just doesn't seem to recognize any text at all.

    I went through the code, you already have the code inserted in it. What could I be doing wrong?

    Hope you respond :)

    PS: I am not into this for a profit motive, just interested because this is something new with VB6.

    ReplyDelete
    Replies
    1. Germ and HideMarch 27, 2013 at 10:44 PM

      In command prompt (Start>run>cmd) type: tesseract c:\cap.bmp c:\output (make sure that you have cap.bmp, which is an image that contains text, is in c:\).

      If output.txt exists in c:\ (pressumably there is no output.txt previously) then tesseract is running as expected. And I have no idea what goes wrong with my code.

      However, if DOS complains that 'tesseract' is not recognized as internal or external commad, then reinstall tesseract. In the 'Choose Components Dialog' make sure that you leave all components checked as is (default).

      I hope this will help.

      Delete
    2. ImmanuelMarch 28, 2013 at 5:32 AM

      Thanks for your response. The CMD part works fine, I get the output in the text file in C folder. However, when I run your project in VB6 and place the form (window) over any text (like you did in your demo video), I doesnt seem to be capturing any text at all.

      It just captures its borders, pink colored. Where am I going wrong?

      And I am running Win 7 Ultimate, if that helps.

      This is my cap.bmp after I run your project in VB6.

      http://imageshack.us/scaled/landing/191/capou.png

      Hope it helps. :)

      Delete
    3. Germ and HideMarch 28, 2013 at 9:09 AM

      Your 'cap.bmp' shows that the screen capture behaves strangely. My code contains API calls for capturing the screen, may be it is the problem. However, since I'm running WindowsXP, I cannot verify this.

      I suggest you not to use my screen capture code, since it was originally intended for showing the capture and the OCR result in real time in the demo video. I don't think it is useful in real life applications :)

      A common usage would be OCR-ing a scanned image. You can use Windows Image Acquisition (WIA) or EZTWAIN for accessing a scanner.

      I'm sorry that I cannot help you to make my code work on your machine.

      Delete
    4. ImmanuelMarch 29, 2013 at 4:56 AM

      I have been kicking around the code for about two days now. I have got everything working, except for the screen capture part, I can get a whole screen captured, just not the PictureBox part.

      Also, on VB 6 there ain't TransparencyKey property, so had to get some snippet from the internet, still no luck. :P

      Thanks anyway! For this has given me some interest. :)

      Delete
    5. Germ and HideMarch 29, 2013 at 6:09 AM

      Just make sure that you did not reduce your sleep time during those two days :)
      Happy coding!

      Delete
  2. ImmanuelMarch 29, 2013 at 4:56 AM

    This comment has been removed by the author.

    ReplyDelete
  3. UnknownMay 3, 2013 at 12:01 AM

    Hello iMan, could you tell me how did you make it works in Win7? Beacause I´m having the same problem: tesseract works from cmd, but the text has nothing to do with the text in the original image.
    Regarding to the Transparency, you could put at the load of the form the following code:

    yourpicturebox.backcolor vbtrensparent

    Obviously where it says yourpicturebox you have to write the name of the Pcture Box you are using.

    Best regards

    ReplyDelete
  4. Viagra Satın AlAugust 7, 2015 at 11:39 AM

    hi. how can I change font ?

    ReplyDelete
  5. UnknownFebruary 8, 2020 at 4:57 AM

    khalid.sami

    ReplyDelete
  6. UnknownApril 9, 2020 at 9:45 PM

    Hi, i am interested in the vb6 tesseract tutorial. It is not available anymore

    ReplyDelete

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