“One, Two, Three,... Infinity”

This famous title remarkably summarizes the recent evolution of the ideas in quantitative image analysis, and the impact of mathematical morphology on it. “One”, for the case of basic stereological measurements. In fact, they all involve an implicit image transformation. “Two” appears when this transformation is preceded by another one, as a linear erosion (laws of intercepts) or a covariance. With “Three”, we iterate two transformations before the measurements : bi-dimensional openings, for instance. And immediately after, one jumps to infinity with the pattern recognition algorithms, as the Skeletton.