"Rubin Vase. This is one of the most famous optical illusions that exists. There are two things that you can see in this image ... In black you can see two faces looking directly at one another. In white, you can see an interesting curved vase."
great color example reminding us Positive/Negative does not mean Black and White. Also great example of frame shape can be any shape that can add to the story (narrative). source: Pixar Minimalist Poster Set - Monsters Inc, Wall-E, Ratatouille