I’m playing with Photodirector. This part of it is called ‘splash’.
You can outline an area and make the background black and white. Then I changed the hues in the app. The buddlea in our garden are a slightly more red colour. It’s also changed the green of the leaves slightly too.
I think people should play with different apps and learn how interesting they can make editing photos. Not just to enhance photos and airbrush them but to get creative and have fun.