Post-production coloring of B&W footage — digital or manual. Controversial since it distorts original intent, yet sometimes useful for archival and restoration work.
You have black and white material in front of you — an old documentary, classic archival footage, perhaps even a historical feature film from the 1940s. And someone wants it to be in color. This is where colorization comes into play: the subsequent digital or manual coloring of monochrome footage. Sounds simple? It isn't.
The technical side is entirely digital today. You work in DaVinci Resolve, Baselight, or similar systems — or do it frame-by-frame in Photoshop if it needs to be really precise. The process: create masks (which areas get which colors), set color values, adjust saturation. Sounds mechanical, but it's highly interpretive. Because: there is no reference material. You have to guess, research, consult. Was the actor's suit gray or dark blue? Did the wallpaper have a pattern or was it plain? You have to think yourself into the production and reality of the time — or accept that your interpretation is one, not the truth.
In practice, we encounter two opposing camps: One says colorization is falsification, disrespectful to the artistic decision of the original DP and director who shot in black and white. The other argues that restored, colorized versions make archival material accessible — for schools, broadcasts, new generations who wouldn't otherwise engage with old films. Both are right. The key lies in transparency: if you colorize, it should always be clear that it's a restoration interpretation, not the original.
Practically speaking: source material for documentaries, commercials, or press kits can certainly be meaningfully colorized. With artistic works — like a Bergman or Welles — caution is advised. And technically, you should know that good colorization takes time. A 90-minute feature film version can take weeks if you want to be precise. Half-hearted work is immediately apparent: washed-out colors, unnatural transitions, a plastic look that looks worse than the original black and white version.
Related to this: Restoration, Digital Restoration, Color Grading (where grading refers to already colored material). Colorization is a specialized discipline that requires craftsmanship, research, and a good dose of humility.