Text Growing on Leaf

Irregular-shaped texts bring challenges to Scene Text Detection (STD). Although existing regression-based approaches achieve comparable performances, they fail to cover some highly curved ribbon-like text lines. Inspired by morphology, we found that the leaf vein can easily cover various geometries. Specifically, lateral and thin veins are emitted to margin along main vein gradually with the leaf growth. This process can decompose a concave object into consecutive convex regions, which are easier to fit. Hence, the leaf vein is suitable for representing highly curved texts. Considering the aforementioned advantage, we design a leaf vein-based text representation method (LVT), where text contour is treated as leaf margin and represented through main, lateral, and thin veins. We further construct a detection framework based on LVT, namely LeafText. In the text reconstruction stage, LeafText simulates the leaf growth process to rebuild text contours. It grows main veins in Cartesian coordinates to locate texts roughly at first. Then, lateral and thin veins are generated along the main vein growth direction in polar coordinates. They are responsible for generating the coarse contour and refining it, respectively. Meanwhile, Multi-Oriented Smoother (MOS) is designed to smooth the main vein for ensuring reliable growth directions of lateral and thin veins. Additionally, a global incentive loss is proposed to enhance the predictions of lateral and thin veins. Ablation experiments demonstrate LVT can fit irregular-shaped texts precisely and verify the effectiveness of MOS and global incentive loss. Comparisons show that LeafText is superior to existing state-of-the-art (SOTA) methods on MSRA-TD500, CTW1500, Total-Text, and ICDAR2015 datasets.