Color filters play a key role for applications like CMOS image sensors, liquid crystal displays and light emitting diodes. Using a nanohole array as a plasmonic color filter offers important advantages, in particular compatibility with CMOS processes. In this paper, a set of primary filters (red, green and blue) consisting of a square-lattice of
sub-wavelength holes in an aluminum film and a silicon dioxide substrate are presented for employing in CMOS image sensors. Despite their simple structure and ease of fabrication, the results have shown a transmission peak of 30-67 percent with a FWHM of 40 nm, 50 nm and 105 nm in accurate wavelengths of red, green and blue, respectively. Furthermore, reducing the cross-talk of the filters is investigated by utilizing a silicon dioxide overlay to enhance the coupling of SPPs at both sides of the aluminum film.