Low surface brightness galaxies in the local universe .2. Selection effects and completeness of the automated plate measuring survey

We discuss the techniques employed for identifying low surface brightness galaxies for the Automated Plate Measuring (APM) survey. We present the method of calibrating the photometry performed from the APM scans and discuss the uncertainties associated with the calibrations. We also review the possible sources of incompleteness in the survey, and we present the results of a program of simulations to estimate the completeness as a function of galaxy parameters. Finally, we discuss the implications of the survey results and show, in particular, that the observed distribution of central surface brightnesses among all galaxies in one survey held is almost flat for mu(B)(0) > 23 mag arcsec-(2).