- In the presence of light, an observer perceives colour.
- Things appear coloured to an observer because colour corresponds with a property of light that is visible to the human eye.
- The visual experience of colour is associated with words such as red, blue, yellow, etc.
- The perception of colour is a very subjective experience.
- One factor that determines the particular colour an observer sees is the colour of nearby objects.
- Another factor is to do with the well-being of an observer. Health, medications, mood, emotions or fatigue can all affect the eye, vision and perception.
- A further factor is the environment in which colours are observed, the type of object and colour associations.
- Two different observers may see colour differently because of life experience including educational, social and cultural factors.
- The term observer has distinct and different meanings within the fields of special relativity, general relativity, quantum mechanics, thermodynamics and information theory.