TOM: An open-source tongue segmentation method with multi-teacher distillation and task-specific data augmentation

Tongue imaging serves as a valuable diagnostic modality, particularly in Traditional Chinese Medicine (TCM). The quality of tongue surface segmentation significantly affects the accuracy of tongue image classification and subsequent diagnosis in intelligent tongue diagnosis systems. However, existing research on tongue image segmentation exhibits significant limitations, including sensitivity to lighting and background noise, similarity in color with surrounding tissues, and a lack of robust and user-friendly segmentation tools. This paper proposes a tongue image segmentation method (TOM) based on multi-teacher knowledge distillation. By introducing a novel diffusion-based data augmentation method, we notably improved the generalization ability of the segmentation model while reducing its parameter size. Notably, after reducing the parameter count by 96.6% compared to the largest teacher models, the student model still achieves an impressive segmentation performance of 95.22% mIoU. Furthermore, we packaged and deployed the trained model as an online and offline segmentation tool (available at https://itongue.cn/), allowing TCM practitioners and researchers to use it without any programming experience. We also present a case study on TCM constitution classification using segmented tongue patches. Experimental results demonstrate that training with tongue patches yields higher classification performance and better interpretability than original tongue images. To the best of our knowledge, this is the first open-source and freely available tongue image segmentation tool.