How to create a chroma mask?

[CkJ]

Hi there,

I'd like to darken some colors of video, for example as darken red color.
How I have to create the mask?

:thanks:

[Gavino]

See MaskHS (http://avisynth.nl/index.php/MaskHS).
Or perhaps you can do what you want directly with Tweak (http://avisynth.nl/index.php/Tweak), without creating a mask yourself.