<P>PROBLEM TO BE SOLVED: To provide a light source which outputs light having spectral distribution of emitted light that substantially coincides with a spectral sensitivity of human eyes. <P>SOLUTION: The light source such as a ceramic metal halide lamp has a spectral distribution of emitted light which substantially coincides with the sensitivity of the human eyes in a first operating power under a photopic vision condition. When the lamp is operated at operating power that is lower than the first operating power, the spectral distribution of the emitted light changes so that it substantially coincides with the sensitivity of the human eyes under the mesopic vision condition or a scotopic vision condition. <P>COPYRIGHT: (C)2005,JPO&NCIPI 
LIGHT SOURCE FOR IMPROVING VISUAL RECOGNITION UNDER CONDITION OF MESOPIC VISION LIGHTING