Table 3. Different RGB image range distribution.

Tongue category	R̅	G̅	B̅
Red Tongue	140~220	60~90	60~85
Yellow Tongue	110~145	85~130	40~80
Purple Tongue	40~130	50~110	50~100
White Tongue	65~135	60~120	60~120
Light Red Tongue	90~140	40~110	35~130