Continuum removal
Operates a continuum removal on a vector.
continuum_removal(x, wl = as.numeric(names(x)), upper = TRUE)
x |
a numeric vector |
wl |
the wavelengths of the spectra |
upper |
if TRUE, removes the upper convex hull from the spectra, if FALSE, takes the lower convex hull |
This operation is commonly done to normalize reflectance spectra and allow comparison of individual absorption features from a common baseline. The removal is based on the upper convex hull of the spectra.
This function is working on vectors. It may applied on matrix or data.frames
using the apply function, or on Spectra* objects using the
apply_spectra function.
A numeric vector with its continuum removed.
Pierre Roudier pierre.roudier@gmail.com, based on code from Raphael Viscarra-Rossel.
Clark, R.N., and Roush, T.L. 1984. Reflectance spectroscopy: Quantitative analysis techniques for remote sensing applications. Journal of Geophysical Research 89, 6329–6340.
# Loading example data data(australia) spectra(australia) <- sr_no ~ ... ~ 350:2500 s <- apply_spectra(australia, continuum_removal) plot(s) s <- apply_spectra(australia, continuum_removal, upper = FALSE) plot(s)
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