[FFmpeg-user] Generating a difference map

Evert Vorster evorster at gmail.com
Mon Aug 21 10:00:39 EEST 2017

Hi there, Jonathan.

Thank you very much for your reply. I have played around a little with the
blend filter, and might try the approach again.

Kind regards,

On 21 August 2017 at 06:35, Jonathan Baecker <jonbae77 at gmail.com> wrote:

> 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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Evert Vorster
Isometrix Acquistion Superchief

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