I will follow algorithm described in the following blog, but will have to modify some parameters for your case. You can also drop FillingTransform
from the blog code because you don't have holes in your regions.
rbc = ImageCrop[ Import["http://i.stack.imgur.com/wOJps.png"], {300, 340}];
b = DeleteSmallComponents[ColorNegate[Binarize[rbc, .81]], 50];
distT = DistanceTransform[b, Padding -> 0];
marker = MaxDetect[ImageAdjust[distT], 0.02];
w = WatershedComponents[GradientFilter[b, 3], marker,
Method -> "Rainfall"];
cells = SelectComponents[w, "Count", 500 < # < 3000 &];
measures =
ComponentMeasurements[
cells, {"Centroid", "EquivalentDiskRadius", "Label"}];
Show[rbc,
Graphics[{Blue, Circle @@ # & /@ (measures[[All, 2, 1 ;; 2]]),
MapThread[Text, {measures[[All, 2, 3]], measures[[All, 2, 1]]}]}]]

Then bare number of circled cells can be computed with
measures // Length
16
ComponentMeasurements
should be more useful thanSelectComponents
$\endgroup$ – Niki Estner Dec 7 '12 at 13:59MorphologicalComponents
? $\endgroup$ – image_doctor Dec 7 '12 at 14:11Read the FAQs
! 3) When you see good Q&A, vote them up byclicking the gray triangles
, because the credibility of the system is based on the reputation gained by users sharing their knowledge. ALSO, remember to accept the answer, if any, that solves your problem,by clicking the checkmark sign
` $\endgroup$ – Vitaliy Kaurov Dec 9 '12 at 9:03