CIE 1931 luminosity function
<a href="//commons.wikimedia.org/wiki/User:PAR~commonswiki" title="User:PAR~commonswiki">User:PAR~commonswiki</a>, <b>Vectorization: </b> <a href="//commons.wikimedia.org/wiki/User:Waterced" title="User:Waterced">User:Waterced</a>
commons.wikimedia.org/wiki/File:CIE_1931_Luminosity.png