  In this paper I present a new two-dimensional decomposition technique, which
models the surface photometry of a galaxy with an exponential light profile for
both bulge and disk and, when necessary, with a Freeman bar. The new technique
was tested for systematic errors on both artificial and real data and compared
with widely used one-dimensional decomposition techniques, where the luminosity
profile of the galaxy is used. The comparisons indicate that a decomposition of
the two-dimensional image of the galaxy with an exponential light profile for
both bulge and disk yields the most reproducible and representative bulge and
disk parameters.
  An extensive error analysis was made to determine the reliability of the
model parameters. If the model with an exponential bulge profile is a
reasonable description of a galaxy, the maximum errors in the derived model
parameters are of order 20%. The uncertainties in the model parameters will
increase, if the exponential bulge function is replaced by other often used
bulge functions as the de Vaucouleurs law.
  All decomposition methods were applied to the optical and near-infrared data
set presented by de Jong & van der Kruit (1994), which comprises 86 galaxies in
six passbands.
