I was looking at this page, which is a demo allowing the user to choose the colors of certain parts of a motorcycle. It struck me that while the user chooses flat colors, the result still shows the bumps and curves of the bodywork. Now that of course is the result of some patches of translucent white or black that overlays the transparent background. In fact, this is the image they used:
To produce a picture like that, I can imagine cutting out the shapes for the body panels that I want to color dynamically and then painstakingly recreating the gradients to show the reflections coming off the bodywork.
But is that the way this would normally be done? Or is there a tool that would allow me to select the base color of the body panel and delete that, while leaving the reflections as white or black gradients as we see here?