Applications

Currently, KAPPA has over 200 commands that are available both from the UNIX C-shell and from the ICL command language. They provide the following facilities for data processing:

• FITS readers that generate NDFs and text tables, and the import and export of ancillary data through the NDF FITS extension;
• generation of test data, and NDF creation from text files;
• setting and examining NDF components;
• world co-ordinate systems, and calculation of a sky co-ordinate system;
• arithmetic including a powerful application that handles expressions;
• pixel and region editing, including polygons and circles; re-flagging of bad pixels by value or by median filtering; and pasting arrays over others;
• masking of regions, and of pixels whose variances are too large;
• configuration change: flip, rotate, shift, reshape, subset, permute axes change dimensionality;
• normalisation of NDF pairs;
• compression and expansion of images;
• generalised resampling of NDFs using arbitrary transformations;
• mosaic creation;
• filtering: box, Gaussian, and median smoothing; very efficient Fourier transform, convolution;
• deconvolution: maximum-entropy, Lucy-Richardson, Wiener filter;
• surface and trend fitting;
• statistics including ordered statistics, histogram; pixel-by-pixel statistics over a sequence of images;
• inspection of image values;
• centroids of features, particularly stars; stellar PSF fitting;
• detail enhancement using histogram equalisation and Laplacian, convolution, edge enhancement via a shadow effect, thresholding;
• calculation of polarimetry images;
• creation of one-dimensional profiles through n-dimensional data sets;

There are also many applications for data visualisation:

• use of the graphics database, AGI, to pass information about pictures between tasks; tools for the creation, labelling, selection of pictures, and obtaining co-ordinate information from them;
• image plots with a selection of scaling modes and many options such as axes;
• creation, selection, saving and manipulation of colour tables and palettes (for axes, annotation, coloured markers and borders);
• line graphics: contouring; histogram; line plot of one-dimensional arrays, multiple-line plot of images, and a grid of line plots for cubes; pie sections, and slices through an image; vector plot of an image.
• many aspects of the appearance of line graphics can be tailored to individual needs and stored within `style files'.