If you're looking to watch the film, here are some suggestions:
Depending on the region (the UK’s BBFC vs. the US’s Unrated versions), a downloaded file may be heavily edited. The official "Full Sequence" color versions on physical media or reputable VOD platforms are typically the only way to ensure you are seeing the unrated cut. The Human Centipede 2 Color Version Download --BEST
Director Tom Six has repeatedly stated that the black-and-white cinematography serves multiple purposes: If you're looking to watch the film, here