Abstract: Several patterns of silver halide grain array in emulsion layers are designed and a method of computer simulation of granularity measurement is used to analyse the image layers. These image layers are obtained from the photographic layers with various patterns of grain arrays after exposure and development. The variations of granularity with relative densities are analysed. In the simulating measurements of granularities for the patterned grain layers, it is found that a minor variation in sampling aperture size causes a considerable fluctuation of the granularity values measured. That differs from that of the conventional photographic layers in which grains are randomly distributed. It may be predicted that the shape of sampling aperture and its orientation over the samples will have an appreciable influence on the granularity measurement. A circular aperture, therefore, is supposed to be more appropriate.