The nonlinearities of photographic film are such that saturation effects at high exposure levels can be compensated for by increased differential area effective exposure. This can be achieved by a properly formulated spatial distribution of exposing illumination, on a differential area basis. A balance between film saturation and spatial modulation permits the synthesis of specified differential area transmission characteristics, as a function of the amplitude of the exposing light. The average differential area transmission function synthesis problem is posed in integral equation form, and an approximate solution technique is presented. Restrictions by actual film properties on the function to be synthesized are presented in the form of easily applied estimates.