  Contour based scene text detection methods have rapidly developed recently,
but still suffer from inaccurate frontend contour initialization, multi-stage
error accumulation, or deficient local information aggregation. To tackle these
limitations, we propose a novel arbitrary-shaped scene text detection framework
named CT-Net by progressive contour regression with contour transformers.
Specifically, we first employ a contour initialization module that generates
coarse text contours without any post-processing. Then, we adopt contour
refinement modules to adaptively refine text contours in an iterative manner,
which are beneficial for context information capturing and progressive global
contour deformation. Besides, we propose an adaptive training strategy to
enable the contour transformers to learn more potential deformation paths, and
introduce a re-score mechanism that can effectively suppress false positives.
Extensive experiments are conducted on four challenging datasets, which
demonstrate the accuracy and efficiency of our CT-Net over state-of-the-art
methods. Particularly, CT-Net achieves F-measure of 86.1 at 11.2 frames per
second (FPS) and F-measure of 87.8 at 10.1 FPS for CTW1500 and Total-Text
datasets, respectively.
