Conv-transformer architecture for unconstrained off-line Urdu handwriting recognition

Unconstrained off-line handwriting text recognition in general and for Arabic-like scripts in particular is a challenging task and is still an active research area. Transformer-based models for English handwriting recognition have recently shown promising results. In this paper, we have explored the use of transformer architecture for Urdu handwriting recognition. The use of a convolution neural network before a Vanilla full transformer and using Urdu printed text-lines along with handwritten text lines during the training are the highlights of the proposed work. The convolution layers act to reduce the spatial resolutions and compensate for the n(2) complexity of transformer multi-head attention layers. Moreover, the printed text images in the training phase help the model in learning a greater number of ligatures (a prominent feature of Arabic-like scripts) and a better language model. Our model achieved state-of-the-art accuracy (CER of 5.31%) on publicly available NUST-UHWR dataset (Zia et al. in Neural Comput Appl 34:1-14, 2021).