Complex sentence: The US-edition cover photo was a 1927 photo taken while the future pope was performing his duties as Vatican ambassador to Germany, cropped, darkened and blurred as compared to the photo used in the UK-edition.
Split into simpler sentences: The US-edition cover photo was a 1927 photo taken while the future pope was performing his duties as Vatican ambassador to Germany. It was cropped, darkened and blurred as compared to the photo used in the UK-edition.