| thr_isodata {rcaiman} | R Documentation |
Calculate a threshold with the isodata method
Description
Threshold calculated with the algorithm by Ridler and Calvard (1978), which was recommended by Jonckheere et al. (2005).
Usage
thr_isodata(x)
Arguments
x |
Numeric vector or a single-column matrix or data.frame able to be coerced to numeric. |
Details
The implementation is based on
the IsoData method of Auto Threshold ImageJ plugin by Gabriel Landini, which is now available
in the autothresholdr package (autothresholdr::auto_thresh()).
However, I found this implementarion more versatile since it is not
restricted to an 8-bit input.
Value
Numeric vector of length one.
References
Jonckheere I, Nackaerts K, Muys B, Coppin P (2005).
“Assessment of automatic gap fraction estimation of forests from digital hemispherical photography.”
Agricultural and Forest Meteorology, 132(1-2), 96–114.
doi:10.1016/j.agrformet.2005.06.003.
Ridler TW, Calvard S (1978).
“Picture thresholding using an iterative selection method.”
IEEE Transactions on Systems, Man, and Cybernetics, 8(8), 630–632.
doi:10.1109/tsmc.1978.4310039.
See Also
Other Binarization Functions:
apply_thr(),
obia(),
ootb_mblt(),
ootb_obia(),
regional_thresholding(),
thr_mblt()
Examples
caim <- read_caim()
r <- gbc(caim$Blue)
thr <- thr_isodata(values(r))
bin <- apply_thr(r, thr)
plot(bin)