One colour on a Monochrome image

[Rusty]

To make it easier, I use Color Balance before Chrominance to exaggerate the reds and boost the contrast.

Then, within Chrominance, the oval tool is far superior to make a clean key.

With practice, it's fast and easy!
Rusty

[pjsssss]

This may also have to be used in conjunction with the region filter.

[Stereodesign]

Cheers, I'll give it a go.

[Aristotelis]

Use the chrominance filter to make a selection of the red berries, then apply the monocrome filter outside your selection

[Stereodesign]

I have a shot in which I want to isolate some Red Berries whilst having the rest of the image in Monocrome, How would I do this?