Although not part of the 'official' restoration of 'Trail to Yesterday" (1918), for fun and experimentation I extracted a single frame from the film to test restoration software with artificial intelligence-based colorization capability.
The results were encouraging, bringing a sense of 'dimensionality' to the image. The next step in such experimentation will be to bring the 'colorized' image into photo-editing software and further color-correct to achieve improved results.
Currently, Vegas Pro 18 video-editing software has AI-based colorization as a special effect setting in which to colorize entire scenes from digitized video. This has not been tested as of this posting.