As discussed in Chapter 3, there are two basic types of device that you can display on with MIRIAD . One is a TV-server type device, and the other is a PGPLOT device. These are specified via the server and device keywords, respectively. Tasks use one or the other, but never both. A TV device offers interactive modification of the displayed image (zooming, panning, lookup table modification, transfer function alteration).
PGPLOT devices also offer interactive capability, depending upon the implementation. Lookup table and transfer function modification is available, but not zooming and panning. In addition, a cursor is available to return quantities (such as value and coordinate) from the display. Of course, PGPLOT devices are much more common than TV servers, and in particular include hard-copy devices. We discuss TV display tasks first, and then PGPLOT-display tasks.