graphics: Graphics and image display packages.

• stplot: General plotting utilities.

Description

The `st4gem.graphics' package contains two subpackages of tasks for viewing one- and two-dimensional data. These tasks are not necessarily specific to HST data. They tasks are designed to make use of IRAF image formats (OIF, STF and QPOE), and ST4GEM binary tables. A summary of the available packages is given in Table 1 below; a more detailed summary can be found in the following sections and the help for each package.

            Table 1.  Graphics Packages
+--------------------------------------------------------+
| Package    | Description                               |
+--------------------------------------------------------+
| stplot     | General data plotting                     |
+--------------------------------------------------------+

There currently remains some separation between the capabilities of displaying one-dimensional data (spectra) and two-dimensional data (bit-mapped raster images). In the past, hardware and software limitations enforced a rather strict distinction between vector graphics and image display. This distinction is, however, becoming fuzzier. It is possible to draw any vector graphics to the image display (using an "imd" device and SAOimage). It is also becoming possible to draw gray-scale and color images to some vector graphics "devices" (with the PostScript kernel, for example). Some tasks in the 'stplot' package take advantage of this.

General data plotting

Tasks in the 'stplot' package support drawing graphs from IRAF data. Several tasks also recognize ST4GEM binary tables in addition to the various IRAF image formats.

The two generic tasks 'igi' and 'sgraph' draw graphs from any recognized IRAF data format. (A detailed "IGI Reference Manual" is available from the ST4GEM group by sending e-mail requests to: hotseat@stsci.edu).

Other tasks provide more specific capabilities such as contour plots, labeling of 2-D images with linear or celestial coordinates, drawing vector fields and histograms. The one task specific to HST is 'siaper', which draws the science apertures at the telescope's focal plane at arbitrary scale and rotation.

The 'psikern' GIO kernel allows any IRAF task that produces graphics to fully exploit PostScript capabilities, whether printed directly to a PostScript printer, saved as encapsulated PostScript (EPS) and imported into a document, or rendered on a workstation using a PostScript viewer.

See also

sdisplay, stplot, vdisplay, tv, tv.display