[FFmpeg-user] Question about "normalize" filter

Michael Koch astroelectronic at t-online.de
Mon Jan 30 21:44:02 EET 2023

Am 30.01.2023 um 12:52 schrieb Paul B Mahol:
> On 1/30/23, Michael Koch <astroelectronic at t-online.de> wrote:
>> Am 30.01.2023 um 10:29 schrieb Paul B Mahol:
>>>> You wrote:
>>>> "With default parameters and just strength(2) set to your values, so
>>>> the darkest pixels are left  untouched."
>>>> However I want that black remains untouched. That's not the same,
>>>> because
>>>> the darkest pixels in the image aren't black.
>>>> The workaround is to insert a black pixel before normalizing:
>>>> -vf drawbox=w=1:h=1:color=black,normalize
>>> This command produces more convincing output:
>>> -vf colorlevels=rimin=0:gimin=0:bimin=0:rimax=-1:gimax=-1:bimax=-1
>>> this will pick max pixels values from input and stretch it do default
>>> output max.
>> This command gives almost the same result as my workaround.
>> The meaning of -1 for options is missing in the documentation.
>> It has the same problem as my workaround: The output is only 8-bit.
> filter supports up to 16bit rgb(a), adding float would be trivial.
> patch welcome

Thanks for adding float to colorlevels.
Is there any filter for gamma correction with float?
Does the geq filter support float?


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