Separate luma and color channels

Hi! I want to know what nodes can I use to separate my image in two channels, in this case luminosity and color.

I want to have the flexibility to work in each channel separately. For example if I want to add blur to only the luma channel.

Any idea?

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Colorspace is the node. Convert to one of numerous luma-chroma models or some HSV/HSL variant where luminance or something similar is in lightness/luminance/value component.

They all produce three channels, not two. One luminance based and two color components.

Bitmap can output just Luminance if you just want one channel and want highest performance. There's also a Fuse out there called ColorToMono that gives some more dimensionality reduction options.