This invention can multiplex noise in multilevel image data to reversibly embed visible additional information with a noise-multiplexed distribution while maintaining the atmosphere of the multilevel image data subjected to embedding. The seat back and at least part of the arm portions substantially define a whirlpool area and the arm portions define an open span through which the legs of a user extend when he is seated in the alcove whirlpool seat. The poly-2 layer is etched proximate to the memory array. In this manner, material of the bottom of the tub which would otherwise have been cut away is used to enlarge the virtual height of the magnetic shield.