simple method based on image processing to estimate primary pigment levels of Sichuan Dark Tea during post-fermentation

A new method quantifying the primary pigments of Sichuan Dark Tea (SDT) rapidly based on the image processing was established. The correlations between the color parameters obtained from SDT images by employing the scanner and Photoshop software and the primary pigment levels were analyzed, and the regression models based on these color parameters were established as well. The results showed that the contents of theaflavin, thearubigins and theabrownin significantly correlated with the parameters of RGB and CMYK modes. The contents of chlorophyll (Chl) Chl-a and Chl-b had high correlation with the parameters of RGB and HSB modes. All the regression models established had the best goodness of fit, in the 95 % confidence intervals, the prediction error of them varied from −3.12 to 2.05 %. Thus, the primary pigments of SDT during post-fermentation could be excellently quantified by the image processing methods developed here.