Racing Club fans' loyalty runs so deep, many won't eat red tomatoes, use red heart emojis, or even sit in a red chair because their biggest rival is Independiente. So we experimented with the optical illusion to create the perfect red Coke effect on match days for Racing Club showing up inside and outside the stadium during the Copa Argentina.

Getting the illusion right took dozens of attempts. One of the most surprising discoveries: the effect only works when there's context around the can. A grey can against a plain blue graphic background fools nobody. The brain needs a full scene (people, environment, light) to complete the trick. What we're really playing with is light interpretation, not color. The eye needs to believe that blue light is washing over the scene, turning a red can grey. Once it accepts that premise, it compensates automatically, and the can reads as red. No red pixels needed. Just the right context, and the brain does the rest.