Using threshold method to separate the edge, coating and body of tongue in automatic tongue diagnosis

In order to achieve an automatic tongue diagnostic system of traditional Chinese medicine, an effective segmentation method for detecting the edge of tongue is very important. We mainly compare the Canny, Snake and threshold (Otsu´s thresholding algorithm) methods for edge segmentation. The segmentation using Canny algorithm may produce many false edges after cutting; thus, it is not suitable for use. The Snake segmentation in tongue requires a larger convergence number and spends too much time. Finally, the threshold method using Otsu´s thresholding algorithm and filtering process can achieve an easy, fast and effective segmentation result in tongue diagnosis. Furthermore, we can separate the tongue coating and tongue body, which are useful in clinical tongue diagnosis, through threshold method. Therefore, the threshold method is useful in the development of clinical automatic tongue diagnosis system.