How to carry out a pixel count of microglial cell somas


I am currently trying to analyze my data collected from IBA1 DAB staining of human microglial cells within different pathologies. Due to the age of the patients at death (>80 years old), they have discontinuous processes, and therefore I am unable to carry out a skeletal analysis.

Attached is a picture of the staining images at 40x,

Another option suggested to me was determining the cell soma size via a pixel number count of the somas via manually determining the cell somas. I currently have tried learning how to do this from various papers such as:

If anyone could give me a basic walk through of how to carry out this method I would really appreciate it.