The data values in each of the input NDFs which are to be mapped on to zero intensity and full intensity can be given manually using Parameters RLOW, RHIGH, GLOW, GHIGH, BLOW and BHIGH, but by default they are evaluated automatically. This is done by finding specified percentile points within the data histograms of each of the input images (see Parameter PERCENTILES).
The NDF outputs are intended to be displayed with KAPPA application DISPLAY, using the command:
display out scale=no lut= lut
where `` out '' and `` lut '' are the names of the NDF image and colour table created by this application using Parameters OUT and LUT. The main advantage of this NDF form of output over the PPM form is that any WCS or AXIS information in the input NDFs is still available, and can be used to create axis annotations by the DISPLAY command. The graphics device which will be used to display the image must be specified when running this application (see Parameter DEVICE).
The PPM form of output can be displayed using tools such as xv, or converted into other forms (GIF or JPEG, for instance) using tools such as ppmtogif and cjpeg from the NetPbm or PbmPlus packages. These tools provide more sophisticated colour quantisation methods than are used by this application when creating the NDF outputs, and so may give better visual results.
display m31_col scale=no lut=m31_lut
It can be converted to a GIF (for instance, for inclusion in WWW pages) using the command:
ppmquant 256 m31.ppm ppmtogif m31.gif
These commands assume you have xv, ppmquant and
ppmtogif installed at your site. None of them are
part of KAPPA.
KAPPA --- Kernel Application Package