[Study on illuminant spectrum qualifications for collecting tongue condition].

The traditional light sources in the diagnostic method of tongue collection such as daylight or even candles are easily affected by weather and environment. It isn't favorable for doctors to obtain the accurate information of the tongue condition. The authors' introduce the electric light sources to compensate or replace daylight to obtain stable and real tongue image and scientific results. Lighted by lamps with different radiation spectrum power distribution property, various color rendition and color temperature, the same object will indicate different colors. In this study, spectrum analysis is carried out on four fluorescent lamps and the research is based on iamge identification techniques of tongue color. Applying the methods of spectrum analysis, choose the best one in four illuminants with their specific spectrum by testing instruments and comparing with the results using several spectrum parameters and chromatic coordinates tolerance ellipses. Result showed PHILIPS YPZ220/18-3U. RR. D (with the correlative color temperature 6 500 K) lamp which has the most similar spectrum property with daylight can be used as standard lamp. The research provides the theoretic and experimental basis for choosing electric light sources to replace daylight.