Abstract: The latent image dispersity of tabular Ag (Br I) grains relates itself to the distribution of the iodide ion in the grains. In the present paper, the cross-wedge technique was used to measure-the latent image dispersity caused by sub-images. The analyses of the dispersions of sensitivity between the surface and the interior of the grains have been done according to the measured-image dispersities and the photographic properties of the present emulsions. The results indicated that the iodide ion covered outer layer of AgBr grains cause the speed loss of the emulsion mainly on the surface latent image dispersity, whereas the speed loss of homogeneous AgBrl emulsion has homogeneous dispersion from surface to the interior of the grains, which results from competition of surface and internal sensitivity.

Key words: Iodide distribution, Latent image dispersity, Competition of sensitivity, Cross-wedge technique