Tesseract OCR force pattern

问题

I want to read a specific character sequence with Tesseract like this post : Tesseract OCR: is it possible to force a specific pattern?

I have tried bazaar matching pattern in Tesseract with the pattern \d\d\d\A\A and ocr still recognize other words which doesn't match.

I have tried to use the "tessedit_char_whitelist" parameter but I can't choose the position of the characters with that.

• I launch the command : tesseract image.jpg result -l eng bazaar And I have this message :

Please provide at least 4 concrete characters at the beginning of the pattern

Invalid user pattern \A\A\d\d\d

Tesseract Open Source OCR Engine v3.01 with Leptonica

• image.jpg :

• The result :

  AB123
  ABC12
  A1234
  12345
  ABCD1
  

So it is wrong, I just wanted to catch the sequence "AB123".

Can somebody tell me why the regular expression in my user-patterns file as no effect ? For the configuration, I have strictly followed the bazaar tutorial.

回答1:

Try using this pattern with quantifiers instead.

[a-zA-Z]{2}\d{3}

This should cover only 2 alphabetical characters and 3 digits.

The reason why you are matching everything before is because \w is alphanumeric.

来源：https://stackoverflow.com/questions/31874393/tesseract-ocr-force-pattern