[FFmpeg-user] Question about "normalize" filter

[Paul B Mahol]

On 1/29/23, Michael Koch <astroelectronic at t-online.de> wrote:
> Hello,
>
> if I understood the documentation correctly, the normalize filter maps
> the darkest input pixel to blackpt and the brightest input pixel to
> whitept:
> darkest pixel --> blackpt
> brightest pixel --> whitept
>
> However I need a slightly different mapping:
> A black input pixel shall remain black, and the brightest input pixel
> shall become white.
> black --> blackpt
> brightest pixel --> whitept
>
> With other words: Just multiply all pixels by a suitable constant. Don't
> add or subtract anything.
> Is this possible?
>
> Known workaround: Make sure that the input frame contains a black pixel,
> by inserting one in a corner.

Try attached patch.


>
> Michael
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