Convert Video from Negative Mode to Full Color?

[JonnieGee]

So ... filmed a very important gymnastics performance using a Casio G'Zone Commando smartphone. Problem is that one of the "filmers" somehow accidentally switched into "color negative" mode, and the entire performance video looks like color negative camera film. Do you know of any way to convert a .3gp phone video from "color negative" mode to regular, full color mode? I was told to find someone who has a good graphics editing program that can convert digital negatives (like 'Lightroom'). Does that sound like a viable solution? I've done a lot of video conversion projects over the years, but not anything like this. Please advise if you have any potential solutions.

I'm trying to solve this before my little niece finds out, as someone, perhaps me, may be about to be crucified and/or banned from gymnastics for life. While that could be a blessing in disguise, I have to live with my family for many more years.

Any help is greatly appreciated.

[Selur]

Never tried it, but shouldn't the Avisynth Level filter be able to do that? (http://avisynth.nl/index.php/Levels)
iirc 'color negative' is 'simply' inverting the luma levels (for tv scale) switching 16 to 235 and vise versa,..
so if Levels(0, 1, 255, 255, 0) converts a normal image to a 'color negative' applying it to a 'color negative' should reverse the effect,...

If you posted a short sample of such a clip, me and other might have a look at it.

[TorBru]

Use ffmpeg:

ffmpeg -i "path/to/source/file" -vf negate -c:v libx264 -crf 25 -c:a copy "path/to/destination/file"

[jagabo]

Negative mode usually inverts all channels, be they RGB or YUV. Most editors have an invert filter. Invert() in AviSynth. Invert in VirtualDub. Etc.

If it's black and white negative mode you won't be able to get back the color.

[pandy]

If only one channel was affected then perhaps it will be easier to operate on each channel independently - few tries and you should be ok - Avisynth looks like good tool for this - control over channels is easy and straightforward.
ffmpeg is less intuitive for channel operation than Avisynth IMHO.

[JonnieGee]

Thanks for all the advice Selur, TorBru, jagabo and pandy. I appreciate that! I'm trying it tonight, and I'll post the results.