CFNet: A Coarse-to-Fine Network for Few Shot Semantic Segmentation

Since a huge amount of datasets is required for semantic segmentation, few shot semantic segmentation has attracted more and more attention of researchers. It aims to achieve semantic segmentation for unknown categories from only a small number of annotated training samples. Existing models for few shot semantic segmentation directly generate segmentation results and concentrate on learning the relationship between pixels, thus ignoring the spatial structure of features and decreasing the model learning ability. In this paper, we propose a coarse-to-fine network for few shot semantic segmentation, named CFNet. Firstly, we design a region selection module based on prototype learning to select the approximate region corresponding to the unknown category of the query image. Secondly, we elaborately combine the attention mechanism with the convolution module to learn the spatial structure of features and optimize the selected region. For the attention mechanism, we combine channel attention with self-attention to enhance the model ability of exploring the spatial structure of features and the pixel-wise relationship between support and query images. Experimental results show that CFNet achieves 65.2% and 70.1% in mean-IoU (mIoU) on PASCAL-5(i) for 1-shot and 5-shot settings, respectively, and outperforms state-of-the-art methods by 1.0%.