measure density and spreading of my cells

[ute]

Hello there,

I´m not yet very familiar with ImageJ...but I would like to detect regions of a certain density of cells. My plan is to divide my image into regions with a cell-density higher than a certain marginal value, and regions with less cells per unit/area/square µm or so.
Is there a threshold plugin not for color, greyscale, or things like that, but a threshold for density/ particles per area?

If I understood well, the measurement plugins are for counting particles in a pre-defined region. I want ImageJ to define my ROI, where labeled cells appear more ,than in the surrounding.

I would be very glad if someone could help me!!

Thanks so far

Ute