[WalterBright]

That TIJ cars were distinguishable only by color was made possible by filming in color. A BW movie would not make a film requiring distinguishing colors that filmed as equal shades of grey.

In any case, any such colorizing system would be designed to accept a bit of guidance here and there from the artist. This is much like when an OCR'd document needs a bit of touch-up.

And even if it wasn't perfect, many BW movies would be made much more watchable, like the 1927 Wings, which is crying out to be colorized (and have a soundtrack added).

[m_mueller]

Even though already perfectly enjoyable, I'm thinking Kurosawa films like Seven Samurai and Yojimbo. Man that would be something.

[WalterBright]

Yup. For what is possible, see reddit's colorizedhistory subreddit. The old pictures become much more interesting.