Automatic Classification of Tongue Shape Based on Improved Analytic Hierarchy Process

The shape of the tongue is one of the important characteristics of the tongue, and it is related to the pathological degree of viscera and organs. In TCM (traditional Chinese medicine) tongue diagnosis, the shape of the tongue is subjectively judged by the TCM physician's observation of the tongue body and comparison with the normal tongue shape. However, it is difficult to establish a standard for the normal tongue shape. Moreover, the skewed tongue body will bring a certain error to the classification of the tongue shape. Therefore, this paper proposes a tongue correction method, and the classification of tongue shape is realized on the basis of the proposed method. First, based on the symmetry characteristics of the tongue, this paper uses the Harris corner detection method to extract the tongue's central axis to correct the skewed tongue. Second, seven common tongue shapes were classified by Analytic Hierarchy Process (AHP) based on the tongue length and area related features. The tongue correction experimental results prove the effectiveness of the correction method proposed in this paper, and the tongue classification experimental results prove that classification effect of the tongue shape is more accurate.