Tesseract confuses two numbers
I'm writing an application to scan numbers from an image.
The numbers are using the OCR-B font and may also contain + and > characters.
This is my source image:
The scans using Tesseract weren't very good, even when limiting the character set to the mentioned characters. As I didn't find any OCRB training files for Tesseract, I decided to train it myself.
I created this training image and made a box file from it. The box file is correct, all letters are matched correctly.
Then I did all steps described here to create the other necessary files.
Using this newly trained OCR-B tessdata-set, I get pretty good results on the source image, with one little bug: All 1s are mistaken for 8s and vice-versa. The command used to process the image was
$ tesseract esr2c.tif ocrb-esr2c -l ocrb
and the output for the source image was
0800000001456>8 00000195731208 8 01050008 023+ 08 0301226>20
If you swap all 1s and 8s and compare it to the source image, the output would be correct (except for the last two letters which I can ignore).
How could this happen? Did I do some mistake in the training process? How can I fix it?
Answer
It's likely that somewhere in your box file has incorrect values (characters) for 1 and 8. You can verify using jTessBoxEditor program. If so, correct, regenerate the language data file, and try again.