Tweakable keying effect for videoin

hey there,
im looking for a solution for getting a “every color i want” keying effect. for now i only have found the chroma key effect for dx11 which only allows me to selct prebuilt colors like green or blue and i cant tweak them. for ex9 (where i found a perfect color keymethod) my input looks like this- can anyone send a hint ?
greetings from leipzig