The import code in mitk::Image for a vtkImageData instance does not support multiple scalar component images from VTK:
It seems that the commented code supported multiple components in the past. We need to check how to re-establish the functionality and create a unit test for it.
I managed to import images with multiple scalar components from VTK by taking the same steps as found in mitk::Image::Initialize, but creating the correct PixelType myself. This works flawlessly for RGB(A) images with a component type of unsigned char. Other component types, however, lead to a crash in vtkMitkLevelWindowFilter when the image is rendered. This is probably related to T18411. Another limitation is that the PixelType has to be determined at compile-time.
I'd be happy to provide a patch using my existing import method, but first I'd need to know how to deal with unsupported and/or unknown component types.
Thanks for your analysis. Reading of VTK multi-component images was fixed in T18842. The level window issues with non-integral types are already described in other bugs.