import type { AssetInput, ImageMaskInput } from '../types/images.js';
export { type DecodePngOptions, decodePng, encodePng, type ImageDimensionsInfo, type RgbaImage, readImageDimensions, type SniffedImage, type SniffedImageFormat, sniffImageType, } from './codec.js';
/**
 * What a provider means by a mask.
 *
 * The neutral contract describes a mask by polarity — which colour marks the editable region —
 * because that is how people draw one. Providers disagree: OpenAI reads the alpha channel and edits
 * where it is fully transparent, while Imagen and most diffusion backends read a greyscale image and
 * edit where it is white. Converting between them is this module's whole job.
 */
export type MaskSemantics = 'white-is-editable' | 'black-is-editable' | 'alpha-transparent-is-editable';
/** What a mask must be converted to. */
export interface MaskTarget {
    /** How the provider reads masks. */
    semantics: MaskSemantics;
    /** Dimensions of the image the mask applies to. The prepared mask always matches them. */
    width: number;
    /** Height of the image the mask applies to. */
    height: number;
    /** The provider, named in errors. */
    provider?: string;
}
/** A mask converted for one provider, at the image's exact dimensions. */
export interface PreparedMask extends AssetInput {
    /** Width, equal to the image's. */
    width: number;
    /** Height, equal to the image's. */
    height: number;
    /** Share of pixels marked editable, between 0 and 1. */
    coverage: number;
}
/**
 * Converts a neutral mask into what one provider expects.
 *
 * An injection seam: the bundled `PngMaskTransformer` handles PNG masks, and an application with a
 * native image library can supply its own to accept JPEG or WebP masks or to resample with
 * anti-aliasing.
 */
export interface AssetTransformer {
    /** Converts a mask to the target's semantics and dimensions. */
    prepareMask(mask: ImageMaskInput, target: MaskTarget): Promise<PreparedMask> | PreparedMask;
}
/** Options for the bundled PNG mask transformer. */
export interface PngMaskTransformerOptions {
    /** Luminance, 0–255, at or above which a pixel counts as white. Defaults to 128. */
    threshold?: number;
    /** Largest mask accepted before decoding, as a guard against a decompression bomb. */
    maxPixels?: number;
}
/**
 * Converts PNG masks between polarities and alpha semantics, resizing with nearest-neighbour when
 * the mask's `resizeMode` allows.
 */
export declare class PngMaskTransformer implements AssetTransformer {
    private readonly threshold;
    private readonly maxPixels;
    constructor(options?: PngMaskTransformerOptions);
    /**
     * Converts a PNG mask. Throws for a mask that is not PNG bytes, or of the wrong size when
     * `resizeMode` is `reject`.
     */
    prepareMask(mask: ImageMaskInput, target: MaskTarget): PreparedMask;
    /**
     * One byte per pixel, 1 where editable.
     *
     * A partly transparent pixel is composited over the non-editable colour first, so transparency in
     * a hand-drawn mask never silently widens the editable region.
     */
    private toEditableMap;
}
/**
 * Reads the dimensions of an image a mask will be applied to.
 *
 * Providers need the target size before preparing a mask, and asking them to each parse headers
 * would repeat the same code in every adapter.
 */
export declare function requireImageDimensions(asset: AssetInput, provider: string): {
    width: number;
    height: number;
};
/** Shared default instance, built on first use. */
export declare function defaultMaskTransformer(): AssetTransformer;