Comparative Analysis of Tongue Indices between Patients with and without a Self-Reported Yin Deficiency: A Cross-Sectional Study

Figure 2

Calculation of tongue indices. The tongue area was extracted from an acquired tongue image. The tongue coating area was distinguished from the tongue body area based on the difference in color. The RGB color values in the areas of interest were converted into CIE- color values. Then, the mean values of whole tongue area and tongue body area were calculated. The tongue coating percentage was calculated as the percentage of the pixel number of the tongue coating area to the pixel numbers of the whole tongue area.