Hi Jonathan,
The connected components filter will also output the largest cluster even without the -largest option. However, because the clusters are labelled according to size (with the largest cluster assigned to 1) it may not be easy to see straight away when loading in mrview because of the min-max intensity windowing. Especially if you have lots of clusters.
I’m sure you know this already, but in case you don’t, you can use the right mouse button to change the intensity windowing.
If you are definitely not getting the largest cluster, then this is not the desired behaviour and I’d be happy to take a look at your image.
Cheers,
Dave