SKYMAP 5. Image display

skymap reads FITS images from disk files which are specified in two parts: the image file name and the image directory pathname. When plotting different images from the same directory, only the image name needs to be retyped. Mapping parameters may be read from the FITS image header or set using the Mapping submenu. Image pixels are assumed to be square. If an image is displayed, it is plotted before axes or other information. Two-dimensional FITS-format images of any data type are supported.

Three modes of image display are currently implemented for any Tektronix-emulating terminal: two halftone modes with dots distributed randomly (DOTPLOT) and dots distributed in a constant pattern for each level (HALFTONE), and one contour mode (CONTOUR). Contour intervals and gray levels for halftones are separately maintained. Halftone displays may be scaled linearly, logarithmically, or by a power law. The image is centered with in a display area on the terminal that is defined the same way as for any map that is drawn.