Colour vision is the capacity of an organism to distinguish objects based on the wavelengths (or frequencies) of the light they reflect, emit, or transmit.

Colour is a quality made by the visual brain and so it is not a property of objects, despite what children are taught.

The wavelength reflected from an object is the objective fact: it does not depend upon perception. A 'red' apple does not emit red light. Rather, it simply absorbs all the frequencies of visible light shining on it except for a group of frequencies that are reflected. It is these frequencies which are perceived as red.