>>935874188>88>same dubs againLucky You.
The best thing you can do is convert from the original video. So, if you know where these come from, or if you reverse-search the images, you may have an easier time.
>Dithering reduction algorithmI searched and see nothing. If I were you, I'd learn to appreciate the dithering, or I would search for the original media, and make a conversion from there.
I see no other way for you, but there may be some 'Magical' program out there that eliminates dithering I am unaware of.
Your fortune: Excellent Luck