The particles command performs some particules analysis on a matrix.

particles performs a thresholding on the matrix and returns the list of the particles found with the following information for each one: its center's coordinates, its area, the dimensions of its minor and major axes, the angle of its major axe, its perimeter, and a flag to say whether the matrix' values in the particle are above or below the threshold (a hill or a hole).

You can specify a range of values for the area: the particles out of the range will be filtered out.

Optionally you can ask that the result returned include each particle's shape as a list of points.

The section about Extensions for SmileLab presents ParticlesLib, a library of routines to apply pre-filters before particles and to post-process the results.