Suggestions on how to separate small pixels clusters

Hello,

I'm wondering if anyone has any suggestions to achive the below.

(imaging the sample below over a larger area) I'm trying to figure out a method of just selecting the red areas which are above a certain pixel count in area. In effect, I want to select the small red dot areas and fill them in green.

I've played around with contracting and expanding etc, however, after contracting by 2 for example, I might have to expand by 6/7 pixels to get the all the pixels in a larger shape which have an accute angle (if that makes sense), then it's likely some of those small pixel areas will be picked back up again.

I've tried solving this problem a number of times, but can never figure it out. I'd be really interested to see if anyone has any angles on how to approach this which I haven't yet considered. Even a seed of an idea might help me figure it out for myself.

Thanks in advance!