Optical filter functionality is incorporated into a substrate of a display element thereby decreasing the need for a separate thin film filter and, accordingly, reducing a total thickness of a filtered display element. Filter functionality may be provided by any filter material, such as pigment materials, photoluminescent materials, and opaque material, for example. The filter material may be incorporated in the substrate at the time of creating the substrate or may be selectively diffused in the substrate through a process of masking the substrate, exposing the substrate to the filter material, and heating the substrate in order to diffuse the filter material in the substrate.