kontrastisäännöt

Kontrastisäännöt, meaning "contrast rules" in Finnish, refers to a set of guidelines used in user interface design to ensure sufficient contrast between text and its background. These rules are crucial for improving readability and accessibility, particularly for users with visual impairments such as color blindness or low vision. The primary goal is to make content easy to perceive and understand for everyone.

The most widely recognized standard for contrast ratios is provided by the Web Content Accessibility Guidelines (WCAG). WCAG defines specific contrast ratios that must be met for different levels of accessibility. For normal text, a contrast ratio of at least 4.5:1 is recommended for WCAG AA compliance, and 7:1 for AAA compliance. For large text (18pt or 14pt bold), the ratios are slightly lower, at 3:1 for AA and 4.5:1 for AAA. These ratios are calculated based on the relative luminance of the colors involved.

Adhering to kontrastisäännöt is not only about meeting accessibility standards but also about creating a better user experience for all users. High contrast improves readability in various lighting conditions, such as bright sunlight or dimly lit rooms. It also helps users quickly distinguish between different elements on a screen, reducing cognitive load and enhancing efficiency. Designers often use contrast ratio checking tools to verify that their color choices meet the required standards before implementing them.