Sublingual veins extraction method based on hyperspectral tongue images

Sublingual vein is one of the important features on tongue surface, which may have pathological relationship with some diseases. Extracting sublingual veins accurately is the primitive work of computer-aided tongue disease diagnosis. Most existing sublingual veins extraction methods are using sublingual images captured by traditional CCD cameras. However, these conversional methods impede the accurate analysis on the subjects of sublingual veins because of the limited information of the images. To solve these issues, a hyperspectral tongue imaging system instead of a digital camera is used to capture sublingual images. Then an improved spectral angle mapper (ISAM) algorithm for automatic sublingual veins extraction was presented. In this algorithm, the spectral of sublingual veins were extracted and the spectral angles of all bands and partial bands were calculated respectively. Finally, the sublingual veins were extracted according to the spectral angles. The experimental results demonstrate that this algorithm can extract the sublingual veins more accurately.