import type { RawImage } from './types.js';
/**
 * A horizontal slice of a source image. `data` holds `height` image rows
 * starting at `yOffset`; `sourceHeight` is the full image's height, because
 * reduce-v1's row mapping is defined on the *global* grid — a band that
 * re-derived it from its own height would land on different source rows and
 * stop agreeing with a whole-frame reduction.
 */
export interface SourceStrip {
    width: number;
    height: number;
    sourceHeight: number;
    yOffset: number;
    data: Uint8Array | Uint8ClampedArray;
}
/** Image rows a cell-row band reads, per reduce-v1's mapping. */
export declare function bandSourceRows(sourceHeight: number, rows: number, rowStart: number, rowEnd: number): {
    y0: number;
    y1: number;
};
/**
 * reduce-v1 (ALGORITHM.md §4): integer box filter to exactly (8·columns) × (8·rows)
 * RGBA samples, alpha-weighted. `ignoreAlpha` treats every pixel as a = 255.
 */
export declare function reduceSource(source: RawImage, columns: number, rows: number, ignoreAlpha: boolean): Uint8Array;
/**
 * reduce-v1 over cell rows [rowStart, rowEnd) only, reading a strip that must
 * cover `bandSourceRows`. Output is band-local: (8·columns) × (8·(rowEnd−rowStart)).
 * Every sample is byte-identical to the same region of a whole-frame reduction —
 * the row mapping below is computed from the global `ty`, never from the band.
 */
export declare function reduceBand(strip: SourceStrip, columns: number, rows: number, ignoreAlpha: boolean, rowStart: number, rowEnd: number): Uint8Array;