Physical investigation on biochemical prediction using continuum removal

This paper examines physical bases for biochemical prediction with hyperspectral data. A distinctive absorption feature centered at 2100 nm in dry leaves is focused on. Continuum removal is employed to the original reflectance spectrum from 2030 nm to 2220 nm to eliminate the influence of background. After comparing some representative samples selected from NASA ACCP data set, two features due to different carbon and nitrogen concentrations are discovered in the continuum-removed spectra. (1) The continuum-removed spectrum curve from 2030 nm to 2050 nm are nearly straight, of which the slope is highly correlated with the carbon concentration. (2) An inflexion located at 2054 nm indicates the nitrogen concentration, which is caused by an absorption pit of protein. The slope change is obvious when the nitrogen concentration is high. Both of the features are caused by essential and unique absorption features of cellulose, lignin and protein in this region, which make them physically based and widely applicable.