We present a subwavelength unit cell constructed of nanoantennas which can independently manipulate the amplitude and phase of an incident wave. The unit cell is made of two layers of scatterers, where the first can tune the amplitude and the second the desired phase. We show that metasurfaces composed of this unit cell can be used to achieve arbitrary transmission amplitude and phase profiles. Furthermore, we show that graded metasurfaces nanoantennas along with Fourier transform blocks can be used to realize unique linear space invariant transfer functions. This approach opens opportunity for light processing on flat platforms. Novel examples are presented.