  The gamma-ray astronomical observatory INTEGRAL, succesfully launched on 17th
October 2002, carries two large gamma-ray telescopes. One of them is the
coded-mask imaging gamma-ray telescope onboard the INTEGRAL satellite (IBIS)
which provides high-resolution (~ 12') sky images of 29deg x 29deg in the
energy range from 15 keV to 10 MeV with typical on-axis sensitivity of ~ 1
mCrab at 100 keV (3 sigma, 10E6 s exposure). We report here the general
description of the IBIS coded-mask imaging system and of the standard IBIS
science data analysis procedures. These procedures reconstruct, clean and
combine IBIS sky images providing at the same time detection, identification
and preliminary analysis of point-like sources present in the field. Spectral
extraction has also been implemented and is based on simultaneous fitting of
source and background shadowgram models to detector images. The procedures are
illustrated using some of the IBIS data collected during the inflight
calibrations and present performance is discussed. The analysis programs
described here have been integrated as instrument specific software in the
Integral Science Data Center (ISDC) analysis software packages currently used
for the Quick Look, Standard and Off-line Scientific Analysis.
