  The MACHO collaboration has been carrying out Difference Image Analysis (DIA)
since 1996 with the aim of increasing the sensitivity to the detection of
gravitational microlensing. This is a preliminary report on the application of
DIA to galactic bulge images in one field. We show how the DIA technique
significantly increases the number of detected lensing events, by removing the
positional dependence of traditional photometry schemes and lowering the
microlensing event detection threshold. This technique, unlike PSF photometry,
gives the unblended colours and positions of the microlensing source stars. We
present a set of criteria for selecting microlensing events from objects
discovered with this technique. The 16 pixel and classical microlensing events
discovered with the DIA technique are presented.

Astrophysics