Luminance Contrast Ratio
Luminance ratio is a term used for the useful contrast of a display, the perceived contrast in the context of the room it is installed in. This is the contrast ratio, including the ambient light reflected on the display.
Why it matters
In a 2017 post, the Bureau of Internet Accessibility explains that the background colors of webpages, including highlighted text, might be perceived differently by users with visual impairments, and those with visual or cognitive disabilities might also have difficulty reading text at certain contrast levels.
A measure of the difference between foreground and background. For WCAG 3.0, a new method known as the Advanced Perceptual Contrast Algorithm provides a numeric contrast value relative to perception.
Interface components have a contrast ratio of 3:1, while the text is 4.5:1. Text requires a higher contrast because users need to read it. Interface components don’t require reading and have a lower standard.
Relative luminance and contrast ratio calculator
Best practices
