  The spectrometer SPI on INTEGRAL allows for the first time simultaneous
imaging of diffuse and point-like emission in the hard X-ray and soft gamma-ray
regime. To fully exploit the capabilities of the instrument, we implemented the
MREM image deconvolution algorithm, initially developed for COMPTEL data
analysis, to SPI data analysis. We present the performances of the algorithm by
means of simulations and apply it to data accumulated during the first 2
mission years of INTEGRAL. Skymaps are presented for the 1809 keV gamma-ray
line, attributed to the radioactive decay of 26Al, and for continuum energy
bands, covering the range 20 keV - 3 MeV. The 1809 keV map indicates that
emission is clearly detected by SPI from the inner Galactic radian and from the
Cygnus region. The continuum maps reveal the transition between a point-source
dominated hard X-ray sky to a diffuse emission dominated soft gamma-ray sky.
From the skymaps, we extract a Galactic ridge emission spectrum that matches
well SPI results obtained by model fitting. By comparing our spectrum with the
cumulative flux measured by IBIS from point sources, we find indications for
the existence of an unresolved or diffuse emission component above ~100 keV.
