Abstract. We describe a neuromorphic retina that signals a luminance edge as a spike. In a fast process, the luminance profile of the receptor layer determines the membrane potential of the ganglion cells and their individual, adjustable spiking thresholds. In a slower process, a wave-propagation process, the charge of ganglion cells with high membrane potential will propagate toward neighboring cells with low membrane potential and low spiking threshold, thus signaling the edge as a spike. Following that, the signaled edge (or contour) actively propagates across the retinal map. The retinal signal can be used for a contour-integration or a contour-propagation approach.