[DJ Mogarych]

Вариант для гиков (Powershell + ffmpeg):

Код:

dir 'D:\Photo\temp\*.jpg' |% {
& ffmpeg -i "$($_.fullname)" -vf eq=brightness=-0.28 "D:\Photo\temp2\$($_.name)"
}

https://ffmpeg.org/ffmpeg-filters.html#eq