Centurio: On Drivers of Multilingual Ability of Large Vision-Language
  Model
Authors: name: Gregor Geigle, name: Florian Schneider, name: Carolin Holtermann, name: Chris Biemann, name: Radu Timofte, name: Anne Lauscher, name: Goran Glavaš

Most Large Vision-Language Models (LVLMs) to date are trained predominantly
on English data, which makes them struggle to understand non-English input and
fail to generate output in the desired target language. Existing efforts
mitigate these issues by adding multilingual training data, but do so in a
largely ad-hoc manner, lacking insight into how different training mixes tip
the scale for different groups of languages. In this work, we present a
comprehensive investigation into the training strategies for massively
multilingual LVLMs. First, we conduct a series of multi-stage experiments
spanning 13 downstream vision-language tasks and 43 languages, systematically
examining: (1) the number of training languages that can be included without
degrading English performance and (2) optimal language distributions of
pre-training as well as (3) instruction-tuning data. Further, we (4)
investigate how to improve multilingual text-in-image understanding, and
introduce a new benchmark for the task. Surprisingly, our analysis reveals that
one can (i) include as many as 100 training languages simultaneously (ii) with
as little as 25-50\% of non-English data, to greatly improve multilingual
performance while retaining strong English performance. We further find that
(iii) including non-English OCR data in pre-training and instruction-tuning is
paramount for improving multilingual text-in-image understanding. Finally, we
put all our findings together and train Centurio, a 100-language LVLM, offering
state-of-the-art performance in an evaluation covering 14 tasks and 56
languages.