Seems to be related to

• T28131: [MultiLabel Segmentation] 3D Threshold tool does not work with multiple labels / layers
• T28986: [MultiLabel Segmentation] 2D / 3D Fast Marching tool does not work with multiple labels

Since I found the following comment on a crucial code location for this task: // this is a fix for T28131 / T28986, which should be refactored if T28524 is being worked on

The label mapping is corrupt when following the instructions given in the task description: {2, 2}. However, the source image does not have label value 2 since it was later added in the destination image while the tool has already been already. The method EnsureUpToDateUserDefinedActiveLabel() seems to be explicitly addressing this issue so I will check if I simply need to call it to fix this task.

edit: Everything in that regard is already correct but the preview image that was probably converted from an image to a label set image in the recent past, was not used as such, e.g., only pixels were written but label data was completely ignored.

Request for Discussion:

• Notify tools about selected label changes or label property changes like color?
• Show preview as active or inactive label (with or without border)?