  Semantic information has been proved effective in scene text recognition.
Most existing methods tend to couple both visual and semantic information in an
attention-based decoder. As a result, the learning of semantic features is
prone to have a bias on the limited vocabulary of the training set, which is
called vocabulary reliance. In this paper, we propose a novel Visual-Semantic
Decoupling Network (VSDN) to address the problem. Our VSDN contains a Visual
Decoder (VD) and a Semantic Decoder (SD) to learn purer visual and semantic
feature representation respectively. Besides, a Semantic Encoder (SE) is
designed to match SD, which can be pre-trained together by additional
inexpensive large vocabulary via a simple word correction task. Thus the
semantic feature is more unbiased and precise to guide the visual feature
alignment and enrich the final character representation. Experiments show that
our method achieves state-of-the-art or competitive results on the standard
benchmarks, and outperforms the popular baseline by a large margin under
circumstances where the training set has a small size of vocabulary.
