A method and system of modifying one feature of a high-pressure lamp without significantly affecting the other features, the features including the luminosity, the color rendering index, the color temperature, or the deviation from the black body locus (DUV). An arc discharge is initiated within the arc tube with a ballast imposing an alternating current waveform on the electrodes. In this way, the electrodes change from positive to negative in each cycle of operation. The waveform of each cycle is modified through the ballast to energize one electrode as positive or negative for a longer time than the other electrode, thereby altering the temperature distribution within the arc tube by changing the cold spot and hot spot temperatures in a lamp which has modifiable emission features.