A new approach to phase-only spatial light modulation is proposed in which a given amplitude pattern can be converted into a spatially identical binary phase pattern. A spatial filtering approach is applied to transform spatial amplitude modulation into spatial phase modulation using the Reverse Phase Contrast (RPC) method. The analytical method for achieving this is outlined and experimental results are shown for the generation of a binary phase-only distribution using an amplitude spatial light modulator and a phase-only spatial filter.