/**
 * Blue -> orange transfer function for ultrasound volume rendering.
 *
 * Dependency-free (no three.js) so it can be unit-tested under Node.
 * The ALPHA channel is load-bearing: three's VolumeRenderShader1 samples this
 * ramp as RGBA, so alpha is what turns low-intensity speckle transparent and
 * gives the volume its cloud-like appearance.
 */
export declare function buildBlueOrangeRGBA(size?: number): Uint8Array;