toolbox: General tools packages.

Introduction

There are seven packages within this package that contain general utility tasks for examining, editing, reformatting, and operating on images and tables. All of these packages are implicitly loaded when the `st4gem' package is loaded. Placing these tasks in separate packages merely serves (in this case) to emphasize the logical relationship between them, and to make the individual package menus manageable. A quick summary is given in Table 1 below; a more detailed summary can be found in the following sections.


              Table 1.  General Tools Packages
+-------------------------------------------------------------+
| Package  | Description                                      |
+-------------------------------------------------------------+
| headers  | Tools for examining and editing image headers    |
| imgtools | General image and mask manipulation tools        |
| tools    | General utilities                                |
+-------------------------------------------------------------+

Headers

The `headers' package provides utilities for comparing, examining, and editing image headers. These tasks are particularly useful for GEIS format images, where the image descriptors that are specific to particular groups are stored in the binary portion of the data. Type "help geis" for more information about this data structure.

Imgtools

The `imgtools' tasks are useful for performing operations on images and masks, such as calculations involving multiple images, editing the contents of an image, or examining the image statistics. There are also utilities for stacking multiple images in to one of higher dimension (and vice versa), retrieving world coordinates of pixels, and pixel mask utilities.

If you use non-ST4GEM tasks in the IRAF environment for your analysis, be aware that operations must be performed explicitly on each group in multi-group GEIS files; the default is usually to operate on only the first group. (To learn the syntax for operating on individual image groups, type "help geis".) On the other hand, many ST4GEM tasks either perform the specified operation on all groups, or make some explicit provision (usually in the task parameters) to define the group(s) on which they operate.

A few tasks are specifically designed to make common operations on multi-group data much less tedious. These tasks are patterned after IRAF tasks but incorporate a "groups" parameter, which is a range list for specifying the groups upon which to operate. A few of them also incorporate a "g_accum" parameter in those cases where it makes sense to accumulate a result over all groups within a file. Two tasks are available at present: `gcopy', and `gstatistics'. Others, including `gcalc', `gcombine', and `ghistogram', are planned for the near future.

Tools

The `tools' package offers general utilities such diverse needs as precessing coordinates, converting between time formats, creating unique file names, and making an `apropos' database file.

Other general utilities

Most of the general plotting and analysis tools that users need to display, analyze and interpret their HST data are available within other packages, such as the `graphics', or `analysis' packages.