Automatic recognition of two types of porosity

[Kj101114.]

Hello,

I am a PhD Student working on the characterisation of different porous materials at a pore level.
One of my most interesting specimens has two very distinct types of porosity, demonstrated below:





In the first tomography image hopefully you will be able to identify the individual spherical particles (circled in black in the second image) which consist of crack/slit like porosity. Whereas, the main body of the material has a more sporadic porosity of micro, meso and macro pores.

The idea being that whilst I can identify these different particles by eye, is there a plugin for ImageJ somewhere that will allow computer/machine learning, in order to automatically identify/separate the two types of material, so that I could then calculate the porosity for all spherical particles and bulk material separately?

If anybody has any ideas or would like some more information encase I haven't explained this very well please message - I would be very grateful for any help.

Kind regards,
Katie