In order to ensure a correct rendering of PET images with enabled "Inverted Black to White" lookup table we need to remove this line in the deprecated class/method mitkImageMapperGL2D::ApplyProperties() :

LookupTableProp->GetLookupTable()->ChangeOpacity(0, 0.0); (line 1102)

Removing this line prevents that the background (value 0) is fully transparent if a lookup table is applied and will correctly render the PET image with "Inverted Black to White" lookup table.

The problem is, that this will also prevent to show several opaque images in the same renderwindow. Since always one image will "override" the others with its non translucent background.

See also T10245.