wcag2RelativeLuminance - multiple declarations

Function wcag2RelativeLuminance

Computes WCAG 2 relative luminance from encoded sRGB.

Wcag2Measurement!T wcag2RelativeLuminance(T)(
  SRgb!T color
) pure nothrow @nogc @safe;

Use this overload for ordinary encoded sRGB input. Components must be finite and from 0 through 1 inclusive. Invalid input produces an invalid Wcag2Measurement whose value is NaN. Alpha-bearing input is not accepted and no clipping or gamut mapping is performed.

Parameters

NameDescription
color Normalized encoded sRGB color.

Returns

A valid relative-luminance measurement, or an invalid measurement for input outside the WCAG 2 sRGB domain.

Standards

W3C WCAG 2.2 relative luminance for sRGB.

Example

Black and white define the endpoints of relative luminance. 

import color.rgb :
    SRgbd;

const black =
    SRgbd(0, 0, 0).wcag2RelativeLuminance;

const white =
    SRgbd(1, 1, 1).wcag2RelativeLuminance;

assert(black.valid);
assert(black.value == 0);

assert(white.valid);
assert(white.value == 1);

Function wcag2RelativeLuminance

Computes WCAG 2 relative luminance from linear-light sRGB.

Wcag2Measurement!T wcag2RelativeLuminance(T)(
  LinearSRgb!T color
) pure nothrow @nogc @safe;

Use this overload when transfer-function decoding has already been done. Components must be finite and from 0 through 1 inclusive. This represents the same WCAG sRGB measurement after transfer-function decoding has already been performed explicitly.

Parameters

NameDescription
color Normalized linear-light sRGB color.

Returns

A valid relative-luminance measurement, or an invalid measurement for input outside the WCAG 2 domain.

Standards

W3C WCAG 2.2 relative luminance for sRGB.

Example

import color.rgb : LinearSRgbd;

const black = LinearSRgbd(0, 0, 0).wcag2RelativeLuminance;
const white = LinearSRgbd(1, 1, 1).wcag2RelativeLuminance;

assert(black.valid && black.value == 0);
assert(white.valid && white.value == 1);