Computing system for forming a spatio-temporal accumulation of activity in digital signals. In some computation algorithms, it is necessary to calculate the period of time for which a given digital signal remains active, or the time when it ceases to be so. This calculation is used, among other things, for analysis of movement in image sequences and requires spatio-temporal integration of this type of signal. This invention consists of a system capable of performing this type of calculation in real time. The system is based on the serial conversion of the input data, the use of a single summer for the entire input space and the storage of the load data in a random-access memory. After this circuitry are arranged a comparator and a counter which is or is not incremented depending on the result from the comparator at each image point, and set to zero after each photogramme. A diagram of the system can be seen in figure 1. <IMAGE>