An active matrix display device stores a transistor drive voltage on a storage capacitor (24; CS). A light-dependent device (27) effects discharge of the storage capacitor in dependence on the light output of the light emitting display element (2). Power is provided to each pixel from a first power line (26), and one of the light dependent device and the storage capacitor is coupled to a second power supply line (50), to which a varying voltage is provided during a pixel illumination period. By varying the voltage on one of the power supply lines, the discharge characteristics of the capacitor by the optical feedback system are altered to provide compensation for the light-dependent device leakage currents. |