Histogram-based operators

Files
file	countvalues.c
	counts the number of distinct values of an image or a region
file	histo.c
	computes the histogram of an image or a region
file	histodist.c
	computes the distance between two histograms
file	histolisse.c
	smoothed histogram of the gray values
file	histopgm.c
	histogram of the gray values
file	histosieve.c
	eliminates points with values that are seldom in the histogram
file	histstretch.c
	transforms the gray scale by stretching the histogram
file	printhisto.c
	prints the histogram of an image or a region
file	printstats.c
	prints some stats of an image or a region
file	relabel.c
	eliminates 'voids' in the labelling