Definition of colour tone in English:

colour tone

noun

  • 1A shade of a colour, especially one having a particular quality of brightness, deepness, or hue, or producing a particular effect within a picture or other image; (as a mass noun) the distinctive qualities or visual effect of a shade of colour.

  • 2Psychology
    The purity or intensity of a perceived colour (rare).

Origin

Mid 19th century; earliest use found in Elizabeth Sheppard (1830–1862), novelist.