In this paper we propose the use of the Randomized Hough Transform alg
orithm for the determination of the proportions of pure classes presen
t in sets of mixed pixels, for large datasets (for which the determini
stic Hough is prohibitively slow) and in the presence of outliers (i.e
. in cases that the classical Least Square Error method cannot cope).
We show that the Randomized Hough is of constant CPU time, irrespectiv
e of the size of the data sets and can be made even more accurate than
the deterministic Hough for datasets larger than about 50 sample poin
ts. We demonstrate our results both with simulated and laboratory data
. (C) 1997 Elsevier Science B.V.