Saturation Archives | lightcolourvision.org

HSB colour model & saturation

The RGB and HSB colour models differ in the way colours are represented and handled in software and apps.
Both the HSB and RGB colour models involve mixing red, green, and blue light to create various colours.
HSB is popular due to its intuitive colour selection and adjustment in applications like Adobe Creative Cloud for design, photography, or web development.
The S in HSB refers to saturation.

Hue refers to the perceived difference between one colour and another and accounts for colour names such as red, yellow, green or blue.
- Hue can be measured as a location on a colour wheel and expressed in degrees between 0⁰ and 259⁰.
Saturation refers to the perceived difference between one colour and another in terms of purity.
- Saturation is measured between a fully saturated colour (100%) and an unsaturated colour (0%).
- Saturation determines the vividness and richness of colours. Highly saturated colours appear vibrant, while desaturated colours appear muted or pastel-like.
- A fully saturated colour is produced by a single wavelength or a narrow band of wavelengths of light.
- On HSB colour wheels, saturation is usually shown to increase from the centre to the circumference.
Brightness (colour brightness) refers to the difference between a hue that appears bold and vivid at maximum brightness (100%) and then appears progressively darker in tone until it appears black at minimum brightness(0%).
Colour brightness is often apparent in the difference between the way a colour appears to an observer in well-lit conditions compared with its subdued appearance when in shadow or when poorly illuminated.

Saturation is one of the three primary properties of colour, alongside hue and brightness.
- A colour looks saturated when made by a single or a small range of wavelengths.
- A colour made by one wavelength of light is often referred to as a pure spectral colour.
- Unsaturated colours appear faded due to a wider range of wavelengths.
- Saturation is linked to the complexity of light.

Light complexity, linked to saturation, refers to the quantity and range of wavelengths of light used to create a colour.
- Spectral colours are simple because they consist of just one wavelength of light.
- Bands of colour are relatively simple because they are composed of a continuous range of wavelengths.
- Non-spectral colours can be produced from a mix of many wavelengths from different parts of the spectrum, making them the most complex.
In reality, colours are often produced by complex combinations of wavelengths.
The greater the number and spread of wavelengths across the visible spectrum present in a colour, the lower the saturation.
The human eye can perceive millions of different colours due to the complex interactions of wavelengths and the eye’s colour receptors.

The concept of saturation is most comprehensible when connected to a particular colour model.
Examples of colour models include:
In the HSB colour model, the term saturation (S) is used alongside hue (H) and brightness (B).
Some colour models don’t use the term saturation at all.
When changing from one colour model to another, it’s best to change terminology at the same time.