export type DimensionChange = {
    dimension: string;
    before: number;
    after: number;
    delta: number;
    direction: "improved" | "regressed" | "changed";
};
export type ScreenshotDiff = {
    fix_confirmed: boolean;
    changed_ratio: number;
    changed_region: {
        x: number;
        y: number;
        w: number;
        h: number;
    } | null;
    dimensions: DimensionChange[];
    dimensions_note: string;
    warnings: string[];
};
export declare function diffScreenshots(beforeBase64?: string, afterBase64?: string): Promise<ScreenshotDiff>;