Spatial filtering is one of the main assets of optics for information processing. We use spatial filtering for performing many logic operations simultaneously. The input data are arranged in matrix form. The type of operation is usually homogeneous across the matrix. The input is characterized as diffracting, as scattering or as birefringent structure. Specific issues to be addressed here are: incoherent inputs; inhomogeneous programming; simultaneous performance of several operations on all data, for example XOR and AND as parts of a half-adder; utilization of polarization.