OMR(Optical mark recognition) in c#

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C#

C#3.5

Hello,

Now, I have working on Windows Application with c#.Net,
In that I want to make one project related OMR(Optical mark recognition), But I have query regarding how to recognize image character by c# application?
after search on google, i got some site's, blog's or etc, which in that mention about OCR(optical character recognition). But it's free or purchased some .dll or.
Can any body explain in brief.

Thanks,