OCR post processing and spelling correction.
Read the following paper for further information:
@inproceedings{silfverberg2016data,
title={Data-driven spelling correction using weighted finite-state methods},
author={Silfverberg, Miikka and Kauppinen, Pekka and Lind{\'e}n, Krister},
booktitle={The 54th Annual Meeting of the Association for Computational Linguistics Proceedings of the SIGFSM Workshop on Statistical NLP and Weighted Automata},
year={2016},
organization={ACL}
}