A　generalized　dual-plane　technique　for　digital　holographic　imaging　is　proposed.　Two　holograms　are　recorded　at　two　slightly　displaced　planes.　The　complex　amplitude　of　the　plane　reference　wave　is　obtained　according　to　the　measured　intensity　of　the　reference　beam　and　the　spectrum　of　hologram.　The　holograms　are　modified　with　the　known　information　of　the　reference　wave.　Then,　the　modified　holograms　are　reconstructed　by　the　dual-plane　algorithm.　The　zero-order　and　the　twin　images　are　removed　in　the　reconstructed　image.　The　simulation　and　experiments　demonstrate　that　this　method　is　valid　for　both　on-axis　and　off-axis　digital　holography　and　high　resolution　reconstruction　is　achieved　even　with　a　very　small　offset　angle　of　the　reference　beam.　(C)　2016　Published　by　Elsevier　B.V.