The migration algorithm used is a variation of the split-step method Stoffa et al. (1990). A brief description of the basic algorithm can be found in this report Gratwick (2001). Our image gathers are a function of offset ray parameter, Ph, which is given by equation (1):
The flow of the migration and the factors which affect amplitude preservation are outlined in Figure 1. All schematic image gathers are from a hypothetically flat, constant amplitude reflector. The expected image gather after true amplitude migration is seen in the upper-left corner of Figure 1.