This article reviews the history and state-of-the-art optical character recognition systems, such as ABBYY FineReader, Tesseract, CuneiForm, with particular attention given to their inner algorithms, including page layout analysis; page segmentation and document skew angle estimation. The overview includes the description and comparison of different methods proposed for the last 30 years in terms
... [Show full abstract] of speed and versatility. Critical analysis and discussions about the status of the field and open problems are reported. © 2017, Institution of Russian Academy of Sciences. All rights reserved.