4 piston calipers question

So a first update. I thought I would start with the drivers side and surprisingly all of the brake line fittings came free with just minor persuasion.
I have the caliper fully disassembled on the bench, and I now need to go about removing the pistons which appear to be stuck.
Someone here mentioned the grease method of removing the pistons, but my question is what is now the best method to remove the pistons from the caliper housing so I can assess the pistons and the bores?