  In this, the second in a series of three papers concerning the SuperCOSMOS
Sky Survey, we describe the methods for image detection, parameterisation,
classification and photometry. We demonstrate the internal and external
accuracy of our object parameters. Using examples from the first release of
data, the South Galactic Cap survey, we show that our image detection
completeness is close to 100% to within 1.5 mag of the nominal plate limits. We
show that for the Bj survey data, the image classification is externally > 99%
reliable to Bj = 19.5. Internally, the image classification is reliable at a
level of > 90% to Bj=21, R=19. The photometric accuracy of our data is
typically 0.3 mag with respect to external data for m > 15. Internally, the
relative photometric accuracy in restricted position and magnitude ranges can
be as accurate as 5% for well exposed stellar images. Colours (B-R or R-I) are
externally accurate to 0.07 mag at Bj = 16.5 rising to 0.16 mag at Bj = 20.
