I have been working with color adjustment quite a bit, and so I recently took a class on how to adjust color without making a selection in Photoshop.
One new tool for me was the Replace Color tool. It doesn’t work as a layer adjustment, so duplicating the layer first is a good rule of thumb.
I chose a photo of some birds perched on a rope. The original had 2 with blue bellies and 3 with green bellies.
I decided those green bellies should be amped up a bit and turned them purple (okay, magenta).
Such a useful tool! I’m sure it will come in handy as I continue down the road with cover design.