  We describe a method for the extraction of spectra from high dispersion
objective prism plates. Our method is a catalogue driven plate solution
approach, making use of the Right Ascension and Declination coordinates for the
target objects. In contrast to existing methods of photographic plate
reduction, we digitize the entire plate and extract spectra off-line. This
approach has the advantages that it can be applied to CCD objective prism
images, and spectra can be re-extracted (or additional spectra extracted)
without having to re-scan the plate. After a brief initial interactive period,
the subsequent reduction procedure is completely automatic, resulting in
fully-reduced, wavelength justified spectra. We also discuss a method of
removing stellar continua using a combination of non-linear filtering
algorithms.
  The method described is used to extract over 12,000 spectra from a set of 92
objective prism plates. These spectra are used in an associated project to
develop automated spectral classifiers based on neural networks.
