c18:

I believe softmax would assign each particular pixel (voxel) to a single class whereas sigmoid could assign a single pixel (voxel) to multiple classes. Is this correct?


Yes, that would be the case and the choice would depend on the use case you are working on (i.e. does your target contain a single class per pixel or multiple ones)?



 c18:

Also, if we use dice loss as the loss function, are both softmax and sigmoid compatible or is one preferred over the other?


I believe softmax is used in the dice loss implementations I’m aware of and I don’t know, if a sigmoid activation would also work.