// Boundary4 by G.Landini
// Exctracts the 4-connected boundary of binary particles
// 4 Dec 2003
// uses BinaryThin_.class avaliable from dentistry.bham.ac.uk/landinig/
// assumes a white object on a black background

run("BinaryThin ", "kernel_a='1 1 1 1 1 1 1 1 1 ' rotations='none' iterations=1 white");