import { Rect } from '../../types';
/**
 * Generates an image from two binarized images where black pixels are where
 * `compare` is black and `base` is not. This is useful for determining where a
 * white-background form was filled out, for example.
 *
 * Note that the sizes of the bounds, which default to the full image size, must
 * be equal.
 *
 * ```
 *         BASE                  COMPARE                 DIFF
 * ┌───────────────────┐  ┌───────────────────┐  ┌───────────────────┐
 * │                   │  │        █ █ ███    │  │        █ █ ███    │
 * │ █ █               │  │ █ █    ███  █     │  │        ███  █     │
 * │  █                │  │  █     █ █ ███    │  │        █ █ ███    │
 * │ █ █ █████████████ │  │ █ █ █████████████ │  │                   │
 * └───────────────────┘  └───────────────────┘  └───────────────────┘
 * ```
 */
export default function diff(base: ImageData, compare: ImageData, baseBounds?: Rect, compareBounds?: Rect): ImageData;
export interface CountOptions {
    color?: number;
    bounds?: Rect;
}
/**
 * Determines the ratio of black (or custom color) pixels in an image to the
 * total number of pixels.
 */
export declare function ratio(image: ImageData, options?: CountOptions): number;
/**
 * Determines number of black (or custom color) pixels in an image.
 */
export declare function countPixels(image: ImageData, { color, bounds, }?: CountOptions): number;