Colorists are responsible for adding color to black-and-white line art. For most of the 20th century this was done using brushes and dyes which were then used as guides to produce the printing plates. Since the late 20th century it is most often done using digital media, with printing separations produced electronically.
Colorists may work directly for comics publishers (either as employees or freelancers), or they may work for coloring studios which offer their services to publishers. American Color, Olyoptics, and Digital Chameleon are companies notable in this field within the comic strip industry.