1. An electronic image sensor, comprising: a detector array for detecting an input image and for producing an electronic image signal including a plurality of signal samples; and an image intensity processing array having a plurality of nodes, each node connected to a corresponding detector in the detector array, comprising: a discontinuity-preserving smoothing system for producing a smooth image signal from the electronic image signal, wherein large discontinuities in the image signal are substantially preserved in the smooth image signal and small discontinuities in the electronic image signal are substantially smoothed over in the smooth image signal; the discontinuity-preserving smoothing system comprising: a plurality of horizontal resistive elements for imposing a smoothness constraint by restricting a signal difference across a pair of nodes; a plurality of vertical resistive elements for imposing a closeness constraint by restricting a difference between the electronic image signal and the signal on a corresponding node; and a balancing system for producing a smooth image signal by favoring the closeness constraint over the smoothness constraint according to a permeability function, the permeability function substantially being a function of the electronic image signal.