When viewing segmentations we rely on multilabel color map to display each label in a unique color. This is achieved by switching to the multilabel color map followed by running 'use whole image grey values' on the level window slider (also see T28421).
Unfortunately, even after running 'use whole image grey values' not all labels actually get a unique color value. And this is not even happening just in cases where a large number of unique values exist.

Reproduce

• use data from here e132-projekte/Share/FabianAnMITKTeam/T28422
• load image and segmentation
• move segmentation to top of data manager
• change segmentation label map to multilabel
• right click level window slider, then 'used whole image grey values'
• navigate to kidney tumor:

both kidney and tumor are shown in yellow, not allowing us to distinguish them. This is even though the have different labels (kidney is 1, tumor is 6)

I can fix that by manually playing with the level window slider:

but I really should not have to do that. If I do this manually I might inadvertently fuse two other labels without noticing.
Automatically assigning a unique color to each greyscale value should not be difficult.

(MITK Version: 2021.02 on Ubuntu 18.04)