Extraction of tongue contour in X-ray videos

In spite of the development of new image techniques, X-ray remains an important technique in studying speech production phenomena. In this study, we propose an automatic contour extraction method of tongue in X-ray videos. At first, we take a region gradient based edge-detector to find the initial boundary points. As X-ray is high noise image and tongue is frequently occluded by teeth, there are high ratio outliers in the initial boundary point set. To solve this problem, we propose a cluster based point-to-point distance ratio filter to remove the outliers, which greatly reduces the iteration times of later RANSAC and B-Spline approximation for the final boundary points. Our method is nearly full-automatic, and obtains tongue´s accurate contour. The experiments show that the proposed method could be an effective tool for tongue´s continuous motion analysis.