Why Do Colors Look Different Under Streetlights?

Imagine you have a bright red apple. No matter if you look at it in the sunny garden or under the yellow glow of your kitchen lamp, the apple still looks red. This is called color constancy. Your brain is like a smart camera that automatically fixes blurry photos.

Light changes color depending on where it comes from. Sunlight is white and strong. Candlelight is warm and orange. If your eyes didn't have a trick, the red apple might look brown under candlelight because there is less blue light to mix with the red.

Your brain remembers what the apple should look like. It ignores the yellow tint of the lamp and tells you, "That is still an apple." Without this trick, every time you moved from inside to outside, everything would change color wildly. This helps artists paint realistic scenes because they know how their subjects will appear in different lights.