“The agreed-upon technical definition of color,” says Fairchild, “is that it’s a visual perception.”
So don’t try to tell Fairchild an apple is red. He’ll say, no it’s not, technically — red is just your perception.
“I could change the color of illumination on that apple and make it look green or blue or something completely different,” he says. “The redness isn’t a property of the apple. It’s a property of the apple in combination with a particular lighting that’s on it and a particular observer looking at it.”