Color - (Lightness|Value|Tone) (White, Gray, Black scale)

About

Lightness, also known as value or tone, is a property (coordinate) placed on a linear scale where:

  • White is the highest possible value (the lightest)
  • Black is the lowest value (the darkest)
  • Gray is the a medium value. The midpoint between black and white, neither dark nor light.

Some colors are naturally:

  • light like yellow (high lightness, high value)
  • darker, like violet (low lightness, low value)

and can therefore be projected on the greyscale.

Name

Various color models have an explicit term for this property.

Colorspace

Lightness may be used in colorspace as coordinate. Example with HSL.

 1)

Operation

Tint (Increase) vs Shade (decrease)

In subtractive color (i.e. paints), lightness value changes can be achieved by adding black or white to the color.

Both processes (tint and shade) affect the saturation but the hue remains unchanged.

Calculation

From Rgb

from a rgb colorspace

$max = max($red, $green, $blue);
$min = min($red, $green, $blue);
$lightness = ($max + $min) / 2;

Documentation / Reference


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