Plots spectral curves with various levels of loess smoothing to help decide which
loess parameters are best for subsequently smoothing the data (e.g. via procspec()).
(required) a data frame, possibly of class rspec, which
contains a column containing a wavelength range, named 'wl', and spectra
data in remaining columns.
minsmooth
the minimum f value of the loess function to visualize (defaults to 0.05).
maxsmooth
the maximum f value of the loess function to visualize (defaults to 0.20).
curves
the number of curves to display on the same plot (defaults to 5).
specnum
the number of spectral curves, from the data frame, to visualize (defaults to ALL).
ask
logical. if TRUE, asks for user input before changing plot pages
Value
Series of plot with curves processed with varying level of loess smoothing