Photo Palette & Text Contrast

Check palette luminance and choose readable text for photos and graphics.

Try an example: Alpine color palette · Black and white extremes

How it works

Analyze up to 64 six-digit hex colors for relative luminance and contrast against black and white. Use the results to choose watermark or caption colors for opaque backgrounds.

Convert sRGB components to linear light and calculate relative luminance using coefficients 0.2126, 0.7152 and 0.0722.
Contrast ratio is (lighter luminance + 0.05) / (darker luminance + 0.05). Choose black or white by the larger ratio.
A single color cannot certify text over an entire photograph. Check the actual text area and opacity.

Sources

WCAG: Relative luminance and contrast (W3C)

For scripts and AI agents

JSON API: POST https://luminacoloranalyzer.usefulweb.site/api/v1/calculate (same calculation as this page)
Interface description: OpenAPI 3.1 · AI guide: llms.txt
MCP server (Streamable HTTP): https://luminacoloranalyzer.usefulweb.site/mcp · tool name lumina_color_analyzer

Example request

curl -s -X POST https://luminacoloranalyzer.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{"colors":"#164e63 #c5d6a5 #f4e6cf"}'

Related tools

Photo Crop & Resize Planner – Plan a precise crop and output size before resizing a photo.