Abstract: Methods for the ready identification of dynamic defects using switching induced light emission from CMOS gates in complex integrated circuits such as microprocessors are described. The rapid increase in the complexity of logic circuits means that practical gate level identification of the sources of dynamic errors will require methods other than the gate by gate tracing of every possible path taken by a given set of instructions. The methods described here are based on the ability of picosecond imaging circuit analysis to detect the switching activity of every gate of a complex circuit in a single, passive measurement, and the ability of data processing today to compare large two- and three-dimensional files.