SetBlackValue
void SetBlackValue(BlackValue blackValue);
fHalftone->SetBlackValue(Halftone::kLowValueMeansBlack);
halftone->SetBlackValue(Halftone::kLowValueMeansBlack);
SetBlackValue(kHighValueMeansBlack);
halftone.SetBlackValue(Halftone::kLowValueMeansBlack);