Illuminance

In the HSB colour model brightness (colour brightness) refers to 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.

Magenta is a primary colour in the CMY colour model.

Yes! The primary colours red, green and blue are used to produce secondary colours when using the HSB colour model.

The primary colours in the HSB colour model are the same as the RGB colour model: red, green and blue.

Brightness usually refers to the level light whilst colour brightness refers to the level of saturation of a colour.

HSB colour values (codes) are numeric triplets used in software applications and programming to identify different colours.

• A numeric triplet is a code containing three parameters that refer to the hue, saturation, and brightness of a colour.
• For example:
  • The HSB values for pure red are(0, 100%, 100%): Hue: 0°, Saturation: 100%, Brightness: 100%.
  • A lighter, pastel version of red might be (0, 50%, 100%): Hue: 0°, Saturation: 50%, Brightness: 100%.
  • A very dark, muted red could be: Hue (0, 100%, 20%): 0°, Saturation: 100%, Brightness: 20%.
• The values assigned to the three parameters can be used to define millions of different colours.
• Typically, the HSB colour model is implemented as follows:
  • Hue is represented in degrees from 0 to 360, corresponding to locations on the circumference of a colour wheel.
  • Saturation is represented as a percentage, where 100% denotes a fully saturated colour, and 0% denotes a fully desaturated colour.
  • Brightness is represented as a percentage, where 100% denotes the highest luminance of a colour, and 0% denotes the darkest possible shade of a colour.

The terms brightness and colour brightness have distinct meanings. The first refers to a property of light, and the second to a property of colour as detailed below.

• Brightness (as opposed to colour brightness) is used to refer to a property of light.
• Colour brightness is used to refer to how much colour something appears to emit or reflect towards an observer.
• Colour brightness can be understood as the variation in how a colour is perceived by an observer under well-lit conditions compared to its more muted appearance when in shadow or under poor illumination.
• In the HSB colour model:
  • Hue refers to the perceived difference between colours and is usually described using names such as red, yellow, green, or blue.
  • Saturation refers to the vividness of a colour compared to an unsaturated colour.
  • Brightness refers to the perceived difference in the appearance of colours under ideal sunlit conditions compared to poor lighting conditions where a hue’s vitality is lost.
    • Brightness can be measured as a percentage from 100% to 0%.
    • As the brightness of a fully saturated hue decreases, it appears progressively darker and achromatic.

An additive colour model explains how different coloured lights (such as LEDs or beams of light) are mixed to produce other colours.

• Additive colour refers to the methods used and effects produced by combining or mixing different wavelengths of light.
• The RGB colour model and HSB colour model are examples of additive colour models.
• Additive colour models such as the RGB colour model and HSB colour model can produce vast ranges of colours by combining red, green, and blue lights in varying proportions.
• An additive approach to colour is used to achieve precise control over the appearance of colours on digital screens of TVs, computers, and phones.

The terms brightness and colour brightness have distinct meanings. The first refers to a property of light, and the second to a property of colour as detailed below.

• Brightness (as opposed to colour brightness) is used to refer to a property of light.
• Colour brightness is used to refer to how much colour something appears to emit or reflect towards an observer.
• When brightness is used in connection with the HSB colour model it is used alongside hue and saturation and refers to the method of selecting and adjusting colours in software applications such as Adobe Illustrator.
• The HSB colour model is a representation of colours that combines hue, saturation, and brightness components.
• In the HSB brightness represents the intensity or lightness of a colour, with higher values indicating brighter or lighter colours.

The HSB colour model is similar to the RGB colour model insofar as it is an additive model based on RGB primary colours.

• Both RGB and HSB are additive colour models with red, green and blue primary colours. But whilst RGB relies on directly adjusting the amount of red, green and blue light needed to produce other colours the HSB colour model relies on adjusting hue, saturation and brightness.
• Hue refers to the perceived difference between colours and is usually described using names such as red, yellow, green, or blue.
  • Hue can be measured as a location on an HSB colour wheel and expressed as a degree between 0 and 360.
• Saturation refers to the vividness of a colour compared to an unsaturated colour.
  • Saturation is measured between a fully saturated colour (100%) and an unsaturated colour (0%)that appears either:
    • Dull and washed out until all colour disappears, leaving only a monochromatic grey tone (0%).
    • Misty or milky the nearer they are to white.
  • On many HSB colour wheels, saturation decreases from the edge to the centre.
• Brightness refers to the perceived difference in the appearance of colours under ideal sunlit conditions compared to poor lighting conditions where a hue’s vitality is lost.
  • Brightness can be measured as a percentage from 100% to 0%.
  • As the brightness of a fully saturated hue decreases, it appears progressively darker and achromatic.