Applying "Detrend" to the spectra with R

There is a nice math treatment I use to apply to the spectra in NIR. It is the Detrend.
Normally goes together with the SNV, but this time I´m going to apply it alone.
I´m going to use the Yarn data, with this raw spectra:

 

 

Now we load the R package "pracma":

 

library(pracma)

yarndt_NIR<-detrend(t(yarn$NIR),tt="linear")

wavelengths1<-seq(1,268,by=1)  #para "yarn"

matplot(wavelengths1,yarndt_NIR,type="l",lty=1,

+xlab="Wavelength(nm)",ylab="1/R")

 

The spectra change to this one:

 

We can see hou the "trend" effect ( a shift in the baseline) is corrected and the baseline adjusted.

: