When one uses intrinsic frames of reference separately for an asymmetric object and its mirror image, one perceives the mirror image as left-right reversed because of such a nature of the left-right axis that it is determined depending on the top-bottom and front-back axes. When one perceives the mirror image as left-right nonreversed, on the other hand, one is applying a common frame of reference to the object and its mirror image, obtaining the simple result of geometric optics.
