I'm working on a Star Wars project, where there is few deleted scenes in black & white; I'd like to colorize them, and I'm aware that the only way to do it properly is to do it by hand, frame per frame - but I can't think to do it for thousand frames...

The alternative is to find an automatic way to do that for the whole clip - using, for example, ChromaJig avisynth filter, that is way less than perfect, even if it do something - or feed each frame as separate image to one of the online free colorization app - and even if this method is generally better than the previous, results are not very good in many cases...

Someone colorized a b&w video before? If so, how?

I remember a video about how they did the colorization on The Three Stooges. They just rotoscoped absolutely everything. There must be better ways these days. If you must, at least rotoscope with mask tracking (ie Mocha) to dramatically cut down on the effort it takes.

Thanks for the explanation; but don't know if I'm able to follow that path, and, if so, if I will be patient enough!

Interestingly enough Legend3D started out as an effects house for colorization of black & white film, until they realised the process they had created to automate the masking/rotoscoping could be applied to stereographic conversion. The founder has a Ph.D in neuroscience I think, smart guy.

You might find this interesting.
http://babelcolour.com/

He made a wonderful job, hand painting over 7000 frames for a Doctor Who episode... but I will never do something like that!

I made few tests (again, not perfect results, but *maybe* watchable), colorizing each frame using three different free online demo apps; taking the three pictures and median them. Thousand times? NO WAY!

But, reading the article found following the link, I was inspired; what if I do like him, colorizing key frames (one every 20) and interpolate the others? The idea should work but, again, the colorization quality is not that good...

Agreed, every frame by hand is just... crazy. MAYBE you could get away, say, doing every other frame and interpolating the rest. Probably best in that case to lay the chroma from the interpolated on un-warped luma. I mean, if one were to even attempt roto, using Mocha is a must.

Now the math on that is looking a bit better. 50% less footage and track assisted mattes. Unless every other frame the color starts jumping like crazy and it looks like a three year old made them with crayons when daddy wasn't looking.

I don't even know. Like.... create colored sections for the background and track them to the B&W footage? There's got to be something we're missing.

EDIT:Now here's something interesting: http://www.cs.huji.ac.il/~yweiss/Coloriz...ml#recolor

A frame of the B&W original. Then you do a duplicate set with lines drawn to indicate sections where the colors should be. Then through Matlab it calculates where the colors should end (as far as I understand from the quick read).

Yeah, I'd love to see this process at least sped up, if not automated somehow. There's a few features that come to mind that could benefit from this kind of treatment, if it were done correctly.

Just found a tutorial on doom9 forum, to set up and run an automatic colorization software:
https://forum.doom9.org/showthread.php?t=175314

Results seem promising, but I'm too lazy to actually do it myself... maybe some volunteer would give it a try, and post some examples of the results!

Interesting. I wonder if it's possible to adapt it if you already have parts of a scene in color, and want to colorize the rest.