Luminance & Brightness Comparator

Accessibility Compliance

WCAG 2.1 guidelines specify minimum contrast ratios:

• Normal Text: 4.5:1 minimum
• Large Text: 3:1 minimum
• UI Components and Graphics: 3:1 minimum

Visual Hierarchy

Use luminance differences to create effective visual hierarchy:

• Higher contrast for primary content
• Medium contrast for secondary information
• Lower contrast for decorative elements
• Strategic use of brightness for emphasis

Color Schemes

Consider luminance when creating color schemes:

/* Example of a balanced color scheme */
:root {
  --text-primary: #1a1a1a;    /* High luminance contrast */
  --text-secondary: #666666;  /* Medium luminance contrast */
  --text-tertiary: #999999;   /* Lower luminance contrast */
  
  --background: #ffffff;      /* Base luminance */
  --surface: #f5f5f5;        /* Slight luminance difference */
}

What's the difference between luminance and brightness?

While related, luminance and brightness serve different purposes:

• Luminance: Objective measure of light intensity, used for technical calculations and accessibility standards
• Brightness: Subjective perception of light intensity, influenced by surrounding context and human perception

How do I ensure my design meets WCAG contrast requirements?

Follow these steps:

1. Calculate the relative luminance of both colors
2. Determine the contrast ratio using the formula
3. Compare against WCAG requirements:
   • 4.5:1 for normal text
   • 3:1 for large text and UI components
4. Adjust colors if needed to meet requirements

How can I use luminance to improve visual hierarchy?

Consider these guidelines:

/* Example luminance ratios for hierarchy */
.primary-content {
  /* High contrast - easy to read */
  color: #000000; /* L ≈ 0 */
  background: #ffffff; /* L ≈ 1 */
}

.secondary-content {
  /* Medium contrast - still readable */
  color: #666666; /* L ≈ 0.3 */
  background: #ffffff; /* L ≈ 1 */
}

.tertiary-content {
  /* Lower contrast - de-emphasized */
  color: #999999; /* L ≈ 0.6 */
  background: #ffffff; /* L ≈ 1 */
}

Should I always aim for maximum contrast?

Not necessarily. Consider these factors:

• Content importance and hierarchy
• User context and environment
• Design aesthetic and brand guidelines
• Eye strain and readability for long-form content