[FFmpeg-user] Question about "normalize" filter

[Michael Koch]

Am 29.01.2023 um 19:32 schrieb 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.

How must I set the options for the desired behaviour?

Micheal