A method of providing a background image in a portable device includes extracting broadcasting signals of broad-casting channels in a given order on the basis of a background image setting information, and displaying broadcasting images corresponding to the broadcasting signals as the background image on corresponding displaying areas of the portable device. The interference filters are deposited onto prisms, and may be individually held in the mounting structure, or assembled together as a subassembly. The recombinant DNA molecules and the derived polypeptides, fragments, new combinations of partial sequences and variants can be utilised for the therapy of pollen-allergic diseases. Texture mapping and mipmapping can be used to accurately reduce, expand and reorder layers in a viewable image expanded from a canonical expression of the VLSI layout.