1. A processing system comprising: a processor; and a memory coupled to the processor and storing code which, when executed by the processor, causes the processing system to perform a process of using a neural network to process an image, the process including applying an input image to the neural network, the input image including a plurality of units, the neural network including a plurality of observers, each observer including a plurality of neurons, each neuron configured to execute an integrate-and-fire process, each observer configured to generate an output that includes zero or more coordinates; and recognizing a pattern in the input image by processing the input image with the neural network, wherein firing of any particular neuron indicates the presence of a category of patterns in the input image, at a position corresponding to the particular neuron, wherein processing the input image with the neural network includes, for each coordinate in an output of each of the plurality of observers, integrating a corresponding potential over a range of time slices, and for each said unit whose potential exceeds a threshold after integration by the observer, including the coordinate of the unit in an output set of the observer.