All stages of the photographic process arc modelled in vacuum. The preparation of single-crystalline AgBr films and their subsequent dry sensitization with CdBr,, flash exposure and development by vapour deposition of silver are carried out in the same vacuum cycle. Visualization in the electron microscope of the location of sensitivity centres and latent image centers is achieved and the number density of both types of centers is compared. It is shown that similarly to vapour deposition of silver, exposure to light stabilizes the sensitivity centers and prevents their subsequent rearrangement. The connection between the results obtained and the mechanism of latent image formation is discussed.