By rule of tennis law – specifically, the International Tennis Federation, or ITF – a tennis ball should be yellow in colour. The edict was handed down in 1972, after TV viewers had trouble following the movement of white balls.
So why do some people perceive tennis balls as green (myself included)? For one thing, yellow is easy to identify when contrasted with other colours, but more difficult to articulate when there’s nothing to compare it to.
Secondly, people tend to make colour corrections based on lighting conditions, leading some to discount warmer colours like golds, or cooler colours like blues, based on how we perceive and interpret the colour spectrum. It’s possible that people who are active in the evenings under artificial light are more likely to discount warm colors, making the tennis ball appear green… while people active in the daytime and under natural light would discard cool colours, making the ball appear yellow.
Objectively, a tennis ball is yellow, but it all depends on how you see the world 🙂
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