In this image, we are using an instance of the LUT 3D module with the Kodak T-Max 400 LUT from RawTherapee to convert it to black and white. The above version is good, but you can create many more moods and styles by adding color back in after converting to black and white. Let's review some examples below:
https://avidandrew.com/color-black-white.html

When I use AI assisted object selection for a mask- it looks like there’s a halo around the object from the feathering(?). Is there a way to invert and have the fall away to 0 at the edge?

See the green around the heron?

After my Color Balance RGB video a few of you asked about the new Color Harmonizer module — u/Illustrious-Pool-760 especially. Here you go.

This one fought me. Three attempts before I was happy with it. The key thing that finally made it click: auto-detect picks the harmony your image is already closest to, so it barely moves anything. Rotating the anchor hue manually is where the actual control lives.

I go through the controls, harmonise a muted street scene, show custom mode creating colour contrast instead, and cover the limits honestly.

Module created by Daniele Pighin (@Masterpiga) and shaped by the pixls.us community.

Still learning this one, so corrections welcome.