The default is 40 tissues. To be explicit you can specify this via
import ImageML labelfield = ImageML.HeadModelGeneration([img], output_spacing=0.6, add_dura=False, version=ImageML.eHeadModel.head40)For 30 (or 16) tissues you would specify the version head30 (or head16)
import ImageML labelfield = ImageML.HeadModelGeneration([img], output_spacing=0.6, add_dura=False, version=ImageML.eHeadModel.head30)But please note: the versions are an evolution. The head16 segmentation is not the same, with fewer tissues. It is also less accurate, as it was the first version we published (and trained on less training data).