A unified multilingual handwriting recognition system using multigrams sub-lexical units

•We present a unified multilingual system for handwriting recognition.•The system is based on a two step-level recognition system using an optical model and a language model.•We propose to model language modeling using sub-lexical units.•One investigates bilingual recognition on French and English datasets.•Using multigrams units allows to build a multilingual system which benefits to the language combination. We address the design of a unified multilingual system for handwriting recognition. Most of multilingual systems rests on specialized models that are trained on a single language and one of them is selected at test time. While some recognition systems are based on a unified optical model, dealing with a unified language model remains a major issue, as traditional language models are generally trained on corpora composed of large word lexicons per language. Here, we bring a solution by considering language models based on sub-lexical units, called multigrams. Dealing with multigrams strongly reduces the lexicon size and thus decreases the language model complexity. This makes possible the design of an end-to-end unified multilingual recognition system where both a single optical model and a single language model are trained on all the languages. We discuss the impact of the language unification on each model and show that our system reaches state-of-the-art methods performance with a strong reduction of the complexity.