Photopolymers are used in printing, electronics, solid imaging, and holography. In typical applications the illumination from one side, normal to the surface of these materials, initiates a chemical sequence that records the incident light pattern in the polymer. The high optical density of the film and the unidirectional illumination leads to a concentration gradient of the reacting species and their consequent migration toward the illuminated surface from the bulk of the film. As such, one also sees migration from the dark regions of the pattern to the illuminated ones. As a result, the photopolymerization rate and yield vary greatly with the depth and location in the pattern creating a spatially anisotropic distribution of reactants and products. The presence of atmospheric oxygen in the system adds to nonuniformities of imaging. Using the fluorescence based technique for kinetic measurement, optical microscopy, and semiempirical finite element model computations we reconstruct the spatial dependence of photopolymerization in photopolymer films. The model assumes the mobility of every reactive species in photopolymer formulation including oxygen. We propose to control image uniformity by selecting the reactants with predetermined mobility in polymer film and by controlling the oxygen content of the material during imaging.