# Layer Blend Color Mixer

> Preview eight blend modes and opacity for two opaque colors. Mix a source HEX color over a backdrop using normal, multiply, screen, overlay, darken, lighten, difference or exclusion. Calculate the final sRGB color at a chosen layer opacity.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://luminablendmixer.usefulweb.site/ (interactive tool at https://luminablendmixer.usefulweb.site/tool)
- JSON API: POST https://luminablendmixer.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://luminablendmixer.usefulweb.site/api/v1/tool)
- OpenAPI: https://luminablendmixer.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://luminablendmixer.usefulweb.site/mcp - tool `lumina_blend_mixer`

## Inputs
- backdrop (text): Backdrop HEX
- source (text): Source HEX
- opacity (number): Source opacity (%)
- mode (select): Blend mode

## Method
- Separable blend formulas operate on normalized sRGB channel values. Source-over with an opaque backdrop is (1 − opacity) × backdrop + opacity × blend(backdrop,source).
- Results round to 8-bit RGB. This calculator assumes opaque colors; image layer alpha is additionally handled by the browser compositor.