1. An apparatus comprising: a neural network to process an image, the neural network including a first plurality of observers to identify the presence of features in the input image, each of the first plurality of observers including a plurality of neurons each configured to execute an integrate-and-fire process; and a second plurality of observers coupled to the first plurality of observers, each of the second plurality of observers including a plurality of neurons each configured to execute an integrate-and-fire process, each of the second plurality of observers configured to recognize a different type of pattern in the input image, wherein the type of pattern that each observer of the second plurality of observers recognizes is based on the position of said observer within the neural network.