Using the Hilbert transform for 3D visualization of differential interference contrast microscope images

Differential interference contrast (DIC) is frequently used in conventional 2D biological microscopy. Our recent investigations into producing a 3D DI C microscope (in both conventional and confocal modes) have uncovered a fun damental difficulty: namely that the phase gradient images of DIC microscop y cannot be visualized using standard digital image processing and reconstr uction techniques, as commonly used elsewhere in microscopy. We discuss two approaches to the problem of preparing gradient images for 3D visualizatio n: integration and the Hilbert transform. After applying the Hilbert transf orm, the dataset can then be visualized in 3D using standard techniques. We find that the Hilbert transform provides a rapid qualitative pre-processin g technique for 3D visualization for a wide range of biological specimens i n DIC microscopy, including chromosomes, which we use in this study.