interface Dimensions {
    readonly width: number;
    readonly height: number;
    readonly size?: never;
}
interface SquareSize {
    readonly width?: never;
    readonly height?: never;
    readonly size: number;
}
type Format = 'gif' | 'jpg' | 'png' | 'webp';
export type ImagePlaceholderParams = {
    readonly serviceBase?: string | URL;
    readonly text?: string;
    readonly textColor?: string;
    readonly backgroundColor?: string;
    readonly format?: Format;
} & (Dimensions | SquareSize);
/**
 * @returns URL pointing to a placeholder image from an external service.
 * @see https://placehold.co/
 */
export declare function getImagePlaceholder(params: ImagePlaceholderParams): URL;
export {};