The study of abnormal red tongue tip chromatic measurements and analysis

Objective: This study was aimed to measure the chromatic difference of the tongue side and tongue tip, in order to provide quantitative evidence for tongue color diagnosis. Methods: A total of 683 health inspection people were recruited, and tongue photos were taken for each subject. Then applied ICC specific documents for the correction of all tongue photos, tongue side and tongue tip chromatic values (L*, a*, b*, C* and h°) were obtained for furthermore statistical analysis. CIEDE2000 was used for calculating the color difference. Results: 1. The average color difference of tongue tip and tongue side in normal pink tongue was 5.4. 2. When pink tongue has abnormal red tongue tip, the average color difference of tongue tip and tongue side was 10.85. 3. Comparing to those who has 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. Conclusions: 1. Normal pink tongue had a color difference between its tongue tip and tongue side, and it was not very easy to be observed under human´s eyes, and Traditional Chinese medicine (TCM) practitioners believed that this kind of difference has no diagnostic significance. 2. When abnormal red tongue tip occured in abnormal color tongue (including abnormal pink tongue), the average tongue tip and tongue side difference was around 10.239. 3. Abnormal red tongue tip is a sensitive sign indicating abnormal heat in the body, and the measurement of the chromatic values in abnormal red tongue tip is valuable in distinguishing and preventing abnormal heat.