Plasmonic color filters based on the hexagonal arrangement of coaxial hole array in aluminium have been demonstrated to be a promising candidate for color filter development due to their polarization and incident angle insensitivity. They comprise a single nanometer thick metal film, and demonstrate good line width, CMOS compatibility and fine color tunability. However, the low transmittance of the coaxial hole array based filters limits their use in potential applications such as image sensors and displays. This chapter introduces a new method to increase transmittance in coaxial hole array based filters by tuning both localized surface plasmons and surface plasmon polaritons. In this method, small diameter coaxial holes are created along with a large size coaxial hole array to form a combined filter geometry and computational techniques are employed to optimize the parameters within the aluminium film. The simulation results will have potential applications in CMOS image sensors, submicron pixel development, micro-displays and liquid crystal over silicon (LCoS) devices.