Task: Question Generation
Input (English): There are many non-incandescent light sources, such as the fluorescent lamp, high-intensity discharge lamps and LED lamps, which have higher luminous efficiency, and some have been designed to be retrofitted in fixtures for incandescent lights. These devices produce light by luminescence. These lamps produce discrete spectral lines and do not have the broad "tail" of invisible infrared emissions. By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution, the spectrum emitted can be tuned to mimic the appearance of incandescent sources, or other different color temperatures of white light. Due to the discrete spectral lines rather than a continuous spectrum, the light is not ideal for applications such as photography and cinematography.
Output (English): How can luminescent light sources be modified to resemble the appearance of incandescents?