/**
 * Color compositing utilities for raster tiles.
 *
 * Implements physically correct alpha blending using linear color space
 * and Porter-Duff "source-over" compositing. This produces visually
 * accurate results when overlaying semi-transparent colors.
 *
 * @module
 */
import type { Rgba } from "@osmix/shared/types";
/**
 * Composite an ordered list of RGBA pixels using premultiplied alpha.
 *
 * Pipeline per pixel:
 *  1) Convert sRGB (0..255) to linear light (0..1).
 *  2) Premultiply color by alpha.
 *  3) Fold left with Porter–Duff “over” starting from transparent.
 *  4) Unpremultiply and convert back to RGBA (0..255).
 *
 * Returns an RGBA tuple.
 * Notes:
 *  - Drawing the same semi‑transparent color repeatedly increases coverage:
 *      α_n = 1 - (1 - α)^n
 *  - Order matters when colors differ (standard source‑over compositing).
 */
export declare function compositeRGBA(pixels: Rgba[]): Rgba;
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