Simple OCR, finding matching pattern

Could anybody tell me how to make simple OCR? Lets say we have B&W bitmap. It has some letters on it. Let's say that i have pattern for every letter -> b&w bitmap too ... so how do i find matches for patterns the easiest way? The problem may be that some letters may be partially out of bitmap.
Thanx for help,
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"how do i find matches for patterns the easiest way?"
Question: Are you trying to recognize CAPTCHA text?  That is a different problem than typical OCR.

Given your beginner level status, do NOT try to program this yourself.  Use a third-party, shareware, freeware/opensource OCR library.  

Consider the following:

Good list with some duplicates of above items:

Article about doing this with D7 and the MS Office MODI library:

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flashtAuthor Commented:
I tried those but they suck badly... I do have EXACT patters for letters so the only thing I am asking is how to find matches easiest way. I'm not begginer. It's just I think there are better ways than pixel per pixel comparation...
flashtAuthor Commented:
Oh and yes I'm trying to recognize captcha... if you know any free software for that, would be useful too :)
if you have a character set and there are no morphing or obfuscating operations applied to the CAPTCHA, then I would approach the matching problem thusly:
* isolate individual CAPTCHA characters
* do your matching on a per-character basis

Thinking of this problem as an exercise, I might be tempted to translate the characters, in both your matching set and the CAPTCHA, into vector representations and do a comparison on at the representational level.  Think TEX and LaTEX and TrueType.
Forced accept.

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