@ SilverWook
I came across an article years back when I was interested in how they did that "colorization" thing on some classic B&W movies. It was research for what I was planning to do in the future of my Master Timeline For World Domination® and didn't want to re-invent that wheel.
Clearly pre-dating computer processing (1960's and onward), I read of a photo-stencil process -- copy the B&W film through mosaics of colored stenciling to color film (an optical-printer/animation-stand set-up). Unfortunately, all I can find now, in a few quick searches, are references to stenciling that applies tinting directly to film -- not the process of which I once read.
If I come across that info again, I'll post it. BTW, I, too, prefer the computer methodology.
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@ larkofam
I'm posting this info across a few entries ... as I do it myself and ready screenshots. Included will be info on Avisynth and a script to do what I'm demonstrating in my paint program -- if I can figure out the corresponding functions and/or find plug-ins to do same. :)
Avisynth is what I, and many others, use for involved, video & audio manipulation. It outputs a stream of video/audio to a video encoder of your choice to create a movie file. That file, in turn, can be played directly on your computer and/or encoded to disc for a DVD/Blu-ray player. (Most of that is beyond the scope of this posting. See other forum threads for that information.)
BTW, if you have a decent paint program, that's an easy and interactive way to quickly visualize and test the procedures I'm describing.