/** One byte of opacity per pixel, row by row (0 transparent, 255 opaque). */
export interface AlphaRaster {
    width: number;
    height: number;
    alpha: Uint8Array;
}
/** Whether `bytes` start as a PNG file. */
export declare function isPng(bytes: Uint8Array): boolean;
/**
 * The opacity of every pixel of a PNG. `null` when the picture has no
 * transparency at all (no alpha channel and no `tRNS` chunk: every pixel
 * is opaque); `undefined` when the file cannot be read here (not a PNG,
 * damaged, interlaced).
 */
export declare function decodePngAlpha(input: ArrayBuffer | Uint8Array): AlphaRaster | null | undefined;
//# sourceMappingURL=png.d.ts.map