When a certain wavelength is removed by an object through absorption, the object appears the colour contrary to that absorbed. In that case, what happens to the other wavelengths that are incident on that object, given that they too are within the visible spectrum?
In: Physics
The notion that color is only a single wavelength that is not absorbed is misleading. It’s not that, for instance, a red pigment absorbs *every* wavelength except a narrow range that we perceive as red. It’s more accurate to say that a pigment absorbs a fairly narrow range of wavelengths and color is how we perceive that *combination* of other wavelengths.
That is to say, red is as much the *absence of blue* as it is the presence of red. Your eyes see color by combining input from three different kinds of cone cells, each one “tuned” to red, green, or blue. There’s a lot of overlap – yellow, for example, activates the red cones a bit and the green cones a bit, and the blue cones none at all or very little. To see something as *red* it means the blue cones aren’t being activated much at all and the green ones very little. But that still leaves a pretty wide range of wavelengths that will activate the red cones – exactly how many *are* activated, along with how few green or blue cones are activated, tells your brain exactly what hue of red you perceive.
But even that is not the whole story. Really, your eyes take in a *ton* of information and interpret all of it to build a picture of the world. For example, [brown isn’t a wavelength](https://www.youtube.com/watch?v=wh4aWZRtTwU), it’s “orange, in context.” Your brain also interprets what colors are around the thing you’re focusing on, the lighting, what it *expects* to see, and more.
The point is, if the other wavelengths are not absorbed, they will also be reflected into your eyes and they will help define the color.
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