Abstract: Optical filters are used to compensate for changes in LED and pcLED performance resulting from technological advances in device design or manufacturing, with for example the filtered optical output from later generation devices matching or substantially matching the optical performance of earlier generation legacy devices. This can allow the advanced generation devices to be substituted in applications previously supported by the legacy devices, even if the optical performance of the unfiltered advanced generation devices does not satisfy the optical performance specifications required by the application. Somewhat paradoxically, the advantages of using the filters in combination with the advanced generation devices may arise from the filters making the optical performance of the devices worse according to one or more figures of merit.