I’d love to have an illustrated tutorial about such tools. I often find images — my own photos or from elsewhere — that I would like to fiddle with to create illustrations for my sci fi stories. But a graphic artist I am not!
For example, I pulled up a purple cabbage plant from our garden. Holding it upside down by the roots, it looked just like an alien from one of my stories. I snapped a photo, but now I need to tweak it to look more alien-ish and less cabbagey.
How does one learn to do this?