Complex sentence: Kodachrome was the first successfully mass-marketed color film that used a subtractive color method; previous materials, such as Autochrome and Dufaycolor, had used the additive screenplate methods.
Split into simpler sentences: Kodachrome was the first color film that used a subtractive color method to be successfully mass-marketed. Previous materials, such as Autochrome and Dufaycolor, had used the additive screenplate methods.