GUIDE TO COLOUR EXPRESSION UNDERSTANDING
Color perception is subjective, so you need a tool that differentiates one color from all the others and assigns a numerical value.
What is colour?
Colour is a human visual perceptive property. Colour derives from visible spectrum, or light, (light energy distribution versus wavelength) which interacts with eye's photosensitive cells. In the environment around us, materials colour depends by wavelengths of reflecting or transmitting light. The visible light spectrum is from red wavelengths to blue ones, about 360-720 nm.
Three things are required to see the colour:
- A light source
- An object
- An observer/processor
Colour expression
How do you describe the colour of this rose? You'd say it's yellow, lemon yellow, or perhaps canary yellow?
Each people describes and so defines an object colour in a different way.
Consequently it is objectively difficult to communicate a determined colour to someone without making use of a physical standard. To describe in words the colour difference between two objects is a big challenge. Colour perception and interpretation and chromatic comparisons are very subjective. Colour perception is influenced by visual fatigue, age and other physiological factors.
But also without these physical concerns, every observer interprets colours based on his personal perspective, his emotions, his believes and desires. For example, in a moment when you are under pressure to declare acceptable a correspondence between colours, you might be convinced that such correspondence is within tolerance.
The solution to this dilemma is given by an instrument which univocally identifies a colour by accurately measuring it and comparing it every time with full objective standards. In other words, an instrument which differentiates a colour from all others and gives it a numeric value. Before measuring a colour, it is necessary to find a way to describe it.
How to describe colour?
Typical colour description is based on three elements: hue, chromaticity and value (luminosity). Colour description through these three attributes allows to accurately identify a certain colour and to differentiate it from all others.