Dynamo offers several ways to visualize tomograms. The choice of one or other program depends on varios factors, like "How big is the tomogram?" "Are you going to annotate models on them?".
The simplest visualization system is the program dtmshow, callable from the command line and linked by many Dynamo GUIs. It's a lightweight slice-based browser. The user can choose to use it by preloading of the full tomogram or by accessing the disk for each depicted slice ("on-the-fly" modus). dtmshowDoes not allow to make complex annotations, or to register them inside the Catalogue via the model pool
dpreview goes a step further that dtmshow. It is connected with the Catalogue system, in fact 'open with dpreview' is one of the main options that you get when selecting a catalogued tomogram in the dcm GUI.
In dpreviewslices are always accessed "on the fly", so that browsing can be slow (especially if trying to depict slices orthogonal to the x- or y- directions, which demand multiple I/O operations to gather a slice whose pixels are scattered in the disk). The main function of the dpreview is to provide a "preview" of the disk contents of a tomogram, letting the user to specify and area of the tomogram