The simple model of the colour of reflected light from objects (yes, colour perception is a function of the eye/brain) as I understand it is:
Firstly I will write what I understand happens - which may be the source of my misunderstanding.
Consider white light incident on a material.
Photons of particular wavelength can be absorbed by an atom by causing an electron to jump from its "base" state to some higher energy level.
If the remainder of the incident light is reflected or transmitted the colour of the material is whatever the eye/brain perceives to be the colour of white light less the frequencies absorbed.
The material must absorb a range of frequencies otherwise all colours of reflected/transmitted light would appear white until observed through a spectroscope which would indicate individual frequencies missing from the white light spectrum - which would be too little of the whole spectrum to notice.
Which leads to my actual question ....
If an electron has been "excited" by absorbing a photon from the incident light, surely at some moment later in time it will fall to a lower energy level and re-emit the original frequency absorbed? Hence there will be no "missing" frequencies from the reflected / transmitted light and every object will appear to be white? (but of course this does not happen).