Is Rowling herself responsible for the imagery in the movies ?

probably to some extent, but i’ll ask you this: if she saw those storyboards or dailies and had a problem with the imagery do you think she would have spoken up to stop it?

It is known that Rowling had an unusually large amount of control/input in the production of the movies. More so that most authors are afforded. I doubt she designed or dressed the sets herself but I do think those that did were building out directly from her words and ideas.