/**
 * Minimal MetaImage (.mhd) header parser.
 *
 * Deliberately dependency-free (no three.js) so it can run under
 * `node --experimental-strip-types --test`.
 *
 * Only the subset the 4D ultrasound data uses is supported: 3D, uncompressed,
 * uint8. Anything else throws rather than silently mis-rendering.
 */
export type Matrix3x3 = [number, number, number, number, number, number, number, number, number];
/** Row-major identity — the value MetaImage writes when it has no real orientation. */
export declare const IDENTITY_MATRIX: Matrix3x3;
export interface MhdHeader {
    /** DimSize — x is the fastest-varying axis. e.g. [189, 189, 134] */
    dims: [number, number, number];
    /** ElementSpacing in mm. e.g. [1, 1, 1] */
    spacing: [number, number, number];
    /** ElementType, always "MET_UCHAR" here. */
    elementType: string;
    /** CompressedData — always false here (true is rejected). */
    compressed: boolean;
    /** ElementDataFile, relative to the .mhd. e.g. "DZET01_17871377_000.raw" */
    elementDataFile: string;
    /** Offset — world coordinates of voxel (0,0,0). Defaults to the origin. */
    offset: [number, number, number];
    /** TransformMatrix — row-major direction cosines. Defaults to the identity. */
    transformMatrix: Matrix3x3;
    /** AnatomicalOrientation, e.g. "RAI". `null` when absent. */
    anatomicalOrientation: string | null;
    /**
     * MetaImage has no standard way to assert "this is the same world frame as that MRI".
     * DICOM does — FrameOfReferenceUID (0020,0052). MetaImage readers ignore unknown keys,
     * so a producer can carry the UID across as a custom line. `null` when absent.
     */
    frameOfReferenceUID: string | null;
    /**
     * True when Offset or TransformMatrix carry real values, i.e. the header actually places
     * the volume somewhere. A zero offset with an identity matrix is ambiguous — it may mean
     * "at the origin, unrotated" or "nobody filled this in" — and is treated as the latter,
     * because silently trusting it is the dangerous failure mode.
     */
    hasPose: boolean;
    /** True when ElementSpacing is not the placeholder 1 1 1, i.e. real physical voxel size. */
    hasRealSpacing: boolean;
}
export declare function parseMhdHeader(text: string): MhdHeader;
export type RegistrationReason = "no-pose" | "frame-missing" | "frame-mismatch" | "unverified" | "verified";
export interface RegistrationDecision {
    /** Honour the header's placement? */
    registered: boolean;
    /** Did a FrameOfReferenceUID actually prove the shared world frame? */
    frameVerified: boolean;
    reason: RegistrationReason;
}
/**
 * Decide whether a header's pose may be trusted.
 *
 * Two independent things must hold, and the second is the one people forget:
 *
 *  1. the header must actually carry a pose (`hasPose`), and
 *  2. that pose must be expressed in the SAME world frame as the scene.
 *
 * DICOM proves (2) with FrameOfReferenceUID. MetaImage has no such field, so a producer must
 * carry the UID across as a custom line. When the caller names the scene's frame and the file
 * cannot match it, the pose is refused — a pose in another scanner's coordinate system is
 * worse than no pose at all, because it looks authoritative while being wrong.
 *
 * When the caller names no frame, a pose is honoured but reported as `unverified`: nobody
 * checked, and the UI should not claim otherwise.
 */
export declare function resolveRegistration(header: MhdHeader, expectedFrameOfReferenceUID?: string | null): RegistrationDecision;
/**
 * voxel index -> world, as a column-major 4x4 (three.js `Matrix4.elements` order).
 *
 * ITK/MetaImage convention: `world = Offset + D · (Spacing ∘ index)`, with `D` the
 * row-major direction matrix from TransformMatrix.
 *
 * Only meaningful when `header.hasPose` — otherwise this is the identity scaled by
 * spacing, which places the volume at the world origin and means nothing.
 */
export declare function voxelToWorldMatrix(header: MhdHeader): number[];
/** Number of voxels implied by the header — equals the .raw byte length for uint8. */
export declare function voxelCount(header: MhdHeader): number;