7. Tongue Segmentation by Fusing Region-Based and Edge-Based Approaches

A tongue diagnosis system can offer significant information for health conditions. To ensure the feasibility and reliability of tongue diagnosis, a robust and accurate tongue segmentation method is a prerequisite. However, both of the common segmentation methods (edge-based or region-based) have limitations so that satisfactory results especially for medical use are often out of reach. In this chapter, we proposed a robust tongue segmentation method by fusing region-based and edge-based approaches. Before segmentation, the ROI (region of interest), which was used as input for the subsequent segmentation, was extracted in a novel way. Next, we merged adjacent regions utilizing the histogram-based color similarity criterion to get a rough tongue contour. It is essentially a region-based method and hence the results are less sensitive to cracks and fissures on the surface of the tongue. Then, we adopted a fast marching method to connect four detected reliable points together to get a close curve, which is based on edge features. The contour obtained by the region-based approach was utilized to act as a mask during the fast marching process (edge-based) and the mask added limits so that the ultimate contour would be more robust. Qualitative and quantitative comparisons showed that the proposed method is superior to the other methods for the segmentation of the tongue body in terms of robustness and accuracy.