Colour brightness & light intensity | lightcolourvision.org

The perception of colour depends on the wavelengths that reach an observer’s eyes. Red has a longer wavelength, while violet has a shorter wavelength.
Any colour (e.g. red, magenta, or violet) can be defined by its hue, saturation, and brightness.
Saturated colours are produced by a single wavelength of light or a narrow band of wavelengths.
The brightness of a colour depends on the intensity of the light emitted by a light source (e.g., a coloured light bulb) and the amount of light reflected from a coloured surface.
- So, for example, the texture of a surface can affect brightness even when the intensity of the light source remains constant.
The intensity of light, along with factors such as phase and interference, are directly related to the amplitude of an electromagnetic wave.
Amplitude measures the height of light waves from the centre-line of a waveform to its crest or to a corresponding trough.
Colour brightness, light intensity, and the amplitude of a light wave can all be thought of in terms of the number of photons that strike the eye of an observer.
- Therefore, increasing the amplitude of a wavelength of light will increase the number of photons falling on an object, making it appear brighter to an observer.