These images are courtesy of Energex.  The SE Queensland lightning tracker picks up cloud to ground strikes (Cg's), and sometimes very strong in cloud lightning.  The images show the lightning detected in the 5 minutes leading up to the time stamped at the top right hand coner of the map.  So 600 whites on the tracker for example, means that 600 lightning strikes have been recorded in the 5 minute period. 

The record number of Cg's recorded in a 5 minute period since October 1998 is 1 996 on January 28, 2001.