# color/luminance WCAG relative luminance of a color: 0 for black, 1 for white, gamma-correct per the sRGB spec. Use it to pick readable foregrounds — or call `color/contrast-text` directly. ## Syntax

[color/luminance $color]

## Examples

[color/luminance "#000000"]    # 0
[color/luminance "#ffffff"]    # 1
[color/luminance "#808080"]    # 0.21586052

## Returns A number 0-1. nil when the color is unparseable. ## See Also `color/contrast-text`