Film colorization is any process that adds color to black-and-white, sepia, or other monochrome moving-picture images. It may be done as a special effect, to "modernize" black-and-white films, or to restore color segregation. From Wikipedia
The four-part series '1939-1945 – Et le monde bascule' revisits the global scope and atrocities of World War II, sparking discussions on historical accuracy and cinematic style.