/**
 * Cascade Blur Algorithm
 *
 * High-performance Gaussian blur for large radii using pyramid scaling.
 *
 * The key insight: to blur with large radius efficiently:
 * 1. Scale down the image by factor of 2 (with smooth kernel)
 * 2. Apply blur with smaller kernel on reduced image
 * 3. Scale back up (with smooth kernel)
 *
 * The shrink/expand kernels [1, 5, 10, 10, 5, 1]/32 provide sufficient
 * smoothness to maintain 8-bit precision through multiple cascade levels.
 *
 * Performance: O(n) per pixel regardless of blur radius
 * Traditional Gaussian: O(r) per pixel where r is radius
 */
import { type Bitmap } from "./types.ts";
/**
 * Cascade Gaussian blur with asymmetric X/Y radii
 * High-performance blur using pyramid scaling for large radii
 * @param bitmap Input bitmap to blur
 * @param radiusX Blur radius along X axis in pixels
 * @param radiusY Blur radius along Y axis in pixels (defaults to radiusX)
 * @returns New bitmap with blur applied (dimensions may change)
 */
export declare function cascadeBlur(bitmap: Bitmap, radiusX: number, radiusY?: number): Bitmap;
/**
 * Fast Gaussian blur using cascade algorithm
 * This is the recommended blur function for large radii (> 3 pixels)
 * @param bitmap Input bitmap to blur
 * @param radius Blur radius in pixels
 * @returns New bitmap with blur applied (dimensions may change)
 */
export declare function fastGaussianBlur(bitmap: Bitmap, radius: number): Bitmap;
/**
 * Adaptive blur that chooses the best algorithm based on radius
 * For small radii (≤ 3): uses simple separable Gaussian (more precise)
 * For large radii (> 3): uses cascade algorithm (faster)
 * @param bitmap Input bitmap to blur
 * @param radiusX Horizontal blur radius in pixels
 * @param radiusY Vertical blur radius in pixels (defaults to radiusX)
 * @returns Blurred bitmap using the optimal algorithm
 */
export declare function adaptiveBlur(bitmap: Bitmap, radiusX: number, radiusY?: number): Bitmap;