An imaging mechanism for demagnifing features above wavelength into desired images beyond the diffraction limit is proposed in this letter. The super resolution ability ( about two times and even more that of diffraction limit) arises from the surface plasmon wave excitation and amplification associated with metallic grating structure. Two specifically designed masks are projected to the grating surface from both sides, at one of which the superimposed field forms the desired images. Conceptually formalism of the imaging process is presented using spatial Fourier analysis and illustrated with numerical simulations. (C) 2008 Optical Society of America.