[Insight-users] histogram from masked image region only

[a.bongers at mediri.com]

Hi,

a quick and probably easy(?) question, but I did not find anything about ist yet:

I would like to calculate a histogram over an irregular image region. So I masked an image with the required region (inside I left the values and outside I set everything to 0). 
Is there any easy possibility to get the histogram from this region only ? Or do I really have to get the histogram from the whole image and "filter out" the zeros from first bin ?

Would be nice I anybody had a hint!

Thanks 

Andre