Color filters based upon nano-structured metals have garnered significant interest in recent years, having been positioned as alternatives to the organic dye-based filters which provide color selectivity in image sensors, as non-fading 'printing' technologies for producing images with nanometer pixel resolution, and as ultra-high-resolution, small foot-print optical storage and encoding solutions. Here, we demonstrate a plasmonic filter set with polarizationswitchable color properties, based upon arrays of asymmetric cross-shaped nano-apertures in an aluminum thin-film. Acting as individual color-emitting nano-pixels, the plasmonic cavityapertures have dual-color selectivity, transmitting one of two visible colors, controlled by the polarization of the white light incident on the rear of the pixel and tuned by varying the critical dimensions of the geometry and periodicity of the array. This structural approach to switchable optical filtering enables a single nano-aperture to encode two information states within the same physical nano-aperture; an attribute we use here to create micro image displays containing duality in their optical information states.