I recently rebuilt MITK with a limited module selection (removing MitkIOExt) and found myself in a situation where newly created/loaded images do not have a reasonable default "levelwindow" property anymore.

Looking more into this I found that mitk::ImageVtkMapper2D::SetDefaultLevelWindow does not create one. Neither does anything else in the MitkCore module. The first generic place to apply a default "levelwindow" seems to be MitkIOExt's GPUVolumeMapper3D.

This behavior will probably surprise most users. I would suggest to have a default level window already calculated in ImageVtkMapper2D::SetDefaultLevelWindow. If some application for any reason does not want a default level/window, this application would be free to provide a "levelwindow" of its own choice prior to calling DataNode::SetData().