I have been studying how light and vision works. I've come across how colors are formed. From what I have researched ; An objects Color is created from the light that hasn't been absorbed by the object and reflected from it. This makes sense, however my questions follows: If light from a light bulb hits an apple and the Red colored light is able to escape it, we shall see a red apple. But what happens if light from a light bulb hits a green cup and then the green colored light reflected off the cup hits the original apple. Now the light hitting the apple does not contain all the colors of like white light, only green. Do our eyes only detect the light reflecting from first contact with an object ? and how does it deal with light bouncing and reflecting of other objects after the initial contact from the light source ?

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    $\begingroup$ It is more complicated than your naive description see physics.stackexchange.com/questions/552840/… $\endgroup$
    – anna v
    Feb 17 at 18:27
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    $\begingroup$ If you buy a cheap red laser pointer and point it at some non-red objects, you will find that objects we wouldn't describe as red nonetheless do reflect red light. $\endgroup$
    – g s
    Feb 17 at 18:50

2 Answers 2


As anna v already pointed out, for the perception of color not only the wavelength of the light, but also the way our eyes work have to be considered. Another point to consider is that an object we perceive as red does not reflect "red" light (at the high-wavelength end of the visible spectrum) at 100% and all other wavelengths at 0%. It also reflects other wavelengths, and the sum of all reflected light is translated by our eyes into the perception "red". So, if the only available light source gave of only a specific frequency of "green" light, the apple would appear as (dark) green, since it reflects that light to a lesser degree.


It would appear black.
Imagine you have a red apple and a white light bulb. If you shine the light onto the apple and you pass the reflected light through 3 filters(red, blue, and green).
the image on red filter would look completely white, and black on other filters; and if you mix the images on filters you get what the apple really looks like. what if the apple is purple? then the image on blue and red filters would be white. and if the apple is white, then the image on all filters is white


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