OCR of historical printings of Latin texts: problems, prospects, progress

This paper deals with the application of OCR methods to historical printings of Latin texts. Whereas the problem of recognizing historical printings of modern languages has been the subject of the IMPACT program, Latin has not yet been given any serious consideration despite the fact that it dominated literature production in Europe up to the 17th century. Using finite state tools and methods developed during the IMPACT program we show that efficent batch-oriented post-correction can work for Latin as well, and that a lexicon of historical Latin spelling variants can be constructed to aid in the correction phase. Initial experiments for the OCR engines Tesseract and OCRopus show that some training on historical fonts and the application of lexical resources raise character accuracies beyond those of Finereader and that accuracies above 90% may be expected even for 16th century material.