A person can see in dim light however without being able to distinguish colors. Without light there can be no color. If light is the only source of color, how does nature attain its endless diverse palette, and how does our human race get the outstanding effects achieved with color? The answer to the question lies in the interrelationship of three elements. They are; light, the source of color; the object and how it responds to color; and the eye, which is the perceiver of color.

Light is a form of electromagnetic energy. Our eyes are only perceptive to a small percentage of the electromagnetic spectrum called "visible light" whose wavelengths range from approximately 380 nm to about 750 nm.

Color is our response to stimulation by energy at those wavelengths. We have three types of colour receptors, or cones, in our retina. One type is used to detect blues and violets, which have short wavelengths. Another type of cone is used for detecting the yellows and greens, which have a medium wavelength. The third type of cone is used for detecting reds, which have a long wavelength. As they are stimulated in different proportions our visual system constructs the colours we see. Approximately seven million cones are spread over the top layer of the retina in each eye. Although cones cannot function in dim light, they react to bright light very fast. Three trichromatic theory explains that color vision results from the relative intensity of response of the blue, green and red cones. Equal stimulation of all three gives the perception of white.
Colour-blindness is a human imperfection that makes certain colors invisible to the eye because of the lack of function of one or more sets of the cones. For example, someone who is colour-blind may not see the difference between the colours red and grey.