[FFmpeg-user] Generating a difference map

Jonathan Baecker jonbae77 at gmail.com
Mon Aug 21 08:35:09 EEST 2017


Am 16.08.2017 um 17:58 schrieb Evert Vorster:
> Hi there.
>
> I have a video stream that has been generated via Hugin and some fancy
> scripting.
> I also have a video stream, using the same input and remapped with ffmpeg
> remap filter.
>
> The problem that I am having is that there are some color differences
> between the two streams, with the ffmpeg remapped stream not correcting for
> vignetting and color balances.
>
> Since the same pixels are in the same place, would it be possible to create
> a difference map between the two that I can re-use later as a layer over
> the remapped stream to do color corrections?
>
> I have been trying with the vignette and eq filters, but it has been
> driving me insane, as the color variations are just not linear enough
> across the canvas.
>
> Any help would be greatly appreciated.
>
Hi,

maybe you can use the blend filter: blend the two streams with the 
difference blend mode, and the result blend again with difference over 
the stream where the color variance is missing. Something like:

    -i video_without_vignette.mov -i video_with_vignette.mov
    -filter_complex "[0:v]split[a][b];
    [a][1:v]blend=difference[c];[b][c]blend=difference[out]" -map [out]

I have only test this with a compositing software, not in ffmpeg 
directly. But try and see if it works.

Jonathan



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