Why is color important?

Humans do not use color just for identification (“it’s the red truck”).  In everyday life we mainly use color to differentiate differing materials:  grass, dirt, pavement, water, facial features. clothing, ripe fruit from unripe, etc.  We also used color as an aid in visual processes such as scene segmentation, which help us rapidly differentiate and define the world in front of us.

When we see a colorful scene, what we are actually perceiving is how the different materials in front of us reflect and absorb different wavelengths of light. We perceive those differences as colors. Green leaves, for example, reflect green wavelengths of light and absorb red and orange wavelengths. A dark gray asphalt road reflects all the visible wavelengths and thus looks a neutral gray.

A monochrome image can tell you where an object is in space.  A color can tell you what material it is made of.