An apparatus for compositing an output surface (10) from a plurality of input surfaces (1, 2, 3, 4) includes processing circuitry and a composition processor. The processing circuitry is configured to determine whether two or more input surfaces of the plurality of input surfaces (1, 2, 3, 4) can be combined into a single secondary surface for provision to the composition processor. When it is determined that two or more input surfaces of the plurality of input surfaces (1, 2, 3, 4) can be combined into a single secondary surface for provision to the composition processor, the processing circuitry is configured to provide data representing the secondary surface to the composition processor, the data indicating the input surfaces that contribute to the secondary surface.