THE SCIENCE OF SIGHT
The ability to see comes from a collaboration of optical lenses and specialised cells called photoreceptors. When light bounces off the objects around you, it hits your eyes through a lens called the cornea and passes an opening called the pupil, the size of which is controlled by the coloured portion of the eye, called the iris. The light then reaches the back of the eyes, where groups of photoreceptors make up a layer of tissue called the retina. These cells play an integral role in understanding not only the size and shape of objects, but also their colour. When different wavelengths of light hit your retinae they activate different photoreceptor cells, known as cones, of which the eye has millions. There are three types of cone cells: blue cones, green cones and red cones. Each is responsible for detecting a specific wavelength of light, and when all three work together, they can detect a spectrum of colours. When all the cones are equally stimulated by light, the brain perceives the colour in front of it as white.