The current status of the development of the heavy metal iodides as photoconductors for direct and digital imaging is reviewed. The physical properties of these materials are first summarized as regards their application as photoconductors and the growth of their layers onto readout matrixes for digital imaging. A comparison of the results obtained for polycrystalline and oriented layers of mercuric iodide, lead iodide and bismuth tri-iodide, grown by Physical Vapor Deposition (PVD), is presented. The three materials were found to have similar behavior; the influence of layers orientation on electrical properties and on response to radiation is also evaluated. The best results (DQE, MTF, and actual images) reported for devices made with mercuric and lead iodide layers grown onto TFT and CMOS are remarked, and device performance is compared with the one of alternative materials such as a-Se and CdTe. Perspectives of the field such as using nanostructures as precursors for growing epitaxial layers, and possible future research, are also presented. (c) 2013 Published by Elsevier B.V.