ABSTRACT
Objective To measure the chromatic differences of the tongue tip and tongue side and provide quantitative evidence for tongue color diagnosis. Methods Totally 683 healthy people were recruited, and their tongue photos were taken. Then ICC specific documents were used for the correction of all tongue photos, and chromatic values (L*, a*, b*, C*and h°) of tongue tip and tongue side were obtained for further statistical analysis. CIEDE2000 was used for calculating the color differences. Results The average color difference of tongue tip and tongue side in normal pink tongue was 5.4. When pink tongue has abnormal red tongue tip, the average color difference of tongue tip and tongue side was 10.85. Compared with normal tongue tip, the average color difference of tongue tip and tongue side in abnormal color tongue with abnormal red tongue tip increased from 5.4-7.0 to 11.23. Conclusion Red tongue tip is a sensitive sign indicating abnormal heat in the body. Tongue tip quantitative diagnosis is valuable in the determination of heat sign in TCM preventive treatment of disease, and reveal the diagnosis meaning and scientific connotation of red tongue tip.