[Analysis of tongue color under natural daylight based on chromatic aberration correction]

To establish an analytical method for tongue image acquisition under natural daylight based on L*a*b* error correction, and to observe the classification rules of tongue color using color error correction.

The tongue images in 413 cases were collected under natural indoor daylight by using Nikon D70 digital SLR camera, and then the color error was adjusted by using Nikon Capture NX software correction according to Kodak Q-13 grey card. The classification and quantitative analysis of the tongue color after software correction was carried out depending on L*a*b* color space.

The software correction method had good effects in adjusting the tongue color image error. The L* values of light red, deep red and cyanosis tongues decreased as compared with that of light white tongue (P<0.01), while the a* values of light red, deep red and cyanosis tongues increased as compared with light white tongue (P<0.01). There was no significant difference in L* value between deep red tongue and cyanosis tongue, and there was also no significant difference in a* value between light red tongue and cyanosis tongue. The b* values of light red and deep red tongues increased as compared with that of light white tongue (P<0.01), while the b* value of cyanosis tongue decreased as compared with light red and deep red tongues (P<0.01). There was no significant difference in b* value between light white tongue and cyanosis tongue, and there was also no significant difference in b* value between light red tongue and deep red tongue. The a* value of white fur was higher than that of yellow fur (P<0.01), while the b* value of white fur was lower than that of yellow fur (P<0.01). There was no significant difference in L* value between white fur and yellow fur.

The analytical method for tongue image acquisition under natural daylight based on L*a*b* error correction is accurate in color restoration and feasible to operate.