Tongue line extraction

Tongue line refers to the surface of the tongue covered with fissures or lines in deep or shallow shape and is one type of important features in clinical practice of Traditional Chinese Tongue Diagnosis (TCTD). However, it is hard to extract tongue lines completely due to the large variation of the widths of tongue lines and the strong noise caused by the rough surface of tongue and uneven illumination. In this paper, an improved wide line detector (WLD) is presented for tongue line extraction. Based on the characteristics of tongue lines, the original WLD is improved to avoid the undesired separation of a wide line and the influence of uneven lighting conditions. The proposed method has been tested on a total of 286 tongue line images and our experimental results demonstrate that the improved WLD significantly outperforms the original WLD for tongue line extraction by improving the TPR 16.5%, FPR 44.6% and PM 33.4%, respectively.