1. A neural stimulator comprising: an implanted portion having a wireless receiver and an array of electrodes suitable for stimulating retinal neurons; and an external portion having a data processing unit and including a map for association of input data to electrodes, wherein the map establishes a relationship between a set of geographically related input values and a set of geographically related electrodes in the array of electrodes, the relationship providing an arbitrary association between an average of the set of geographically related input values and the set of geographically related electrodes to correct for distortions of the fovea pit.