One of the most important & highly cited papers in all of computer graphics, "Poisson image editing" describes a gradient-based integral system for performing all sorts of image manipulations, including seamless cloning, where target objects are copy/pasted into a scene. This method underlies the cloning tool familiar to Photoshop users.
I conjecture that a similar gradient-based integral system underlies many computational properties of human vision, including color filling defined over segmented, isolated domains.
