  The ability to accurately predict the contrast achieved from high contrast
imagers is important for efficient scheduling and quality control measures in
modern observatories. We aim to consistently predict and measure the raw
contrast achieved by SPHERE/IRDIS on a frame by frame basis to improve the
efficiency and scientific yield with SPHERE at the Very Large Telescope
(VLT).Contrast curves were calculated for over 5 years of archival data using
the most common SPHERE/IRDIS coronagraphic mode in the H2/H3 dual band filter,
consisting of approximately 80,000 individual frames. These were merged and
interpolated with atmospheric data to create a large data-base of contrast
curves with associated features. An empirical power law model for contrast,
motivated by physical considerations, was then trained and finally tested on an
out-of-sample test data set. At an angular separation of 300 mas, the contrast
model achieved a mean (out-of-sample) test error of 0.13 magnitudes with the
residual 5-95% percentiles between -0.23 and 0.64 magnitude respectively. The
models test set root mean square error (RMSE) between 250-600 mas was between
0.31 - 0.40 magnitudes which is equivalent with other state-of-the-art contrast
models presented in the literature. In general, the model performed best for
targets between 5-9 G-band magnitude, with degraded performance for targets
outside this range. This model is currently being incorporated into the Paranal
SCUBA software for first level quality control and real time scheduling
support.
