Added wavelength indication to the original: <a href="//commons.wikimedia.org/w/index.php?title=File:Cie_chromaticity_diagram.png&amp;action=edit&amp;redlink=1" class="new" title="File:Cie chromaticity diagram.png (page does not exist)">image:Cie_chromaticity_diagram.png</a>. 
I'm not so good with the GIMP; the file has grown bigger. Copyright: see the original which was not created by me. (My modifications are PD - <a href="//commons.wikimedia.org/wiki/User:Hankwang" title="User:Hankwang">Han-Kwang</a> <a href="//commons.wikimedia.org/wiki/User_talk:Hankwang" title="User talk:Hankwang">(talk)</a> 12:39, 13 Dec 2004 (UTC))
<a href="//commons.wikimedia.org/wiki/User:Shizhao" title="User:Shizhao">User:Shizhao</a>
Own work, modification of <a href="//commons.wikimedia.org/w/index.php?title=File:Cie_chromaticity_diagram.png&amp;action=edit&amp;redlink=1" class="new" title="File:Cie chromaticity diagram.png (page does not exist)">Image:Cie chromaticity diagram.png</a>