Provided is a color transformation filter including a plurality of nanostructures included in a subpixel and spaced apart from each other, the plurality of nanostructures having a first refractive index, a low refractive index layer provided adjacent to the plurality of nanostructures, the low refractive index layer having a second refractive index less than the first refractive index, and a color transformation element included in the low refractive index layer.