Editing Kruithof curve (section)

==History==
At the emergence of fluorescent lighting in 1941, Kruithof conducted psychophysical experiments to provide a technical guide to design artificial [[lighting]].<ref>{{cite journal|last=Viénot|first=Françoise |author2=Marie-Lucie Durand |author3=Elodie Mahler|title=Kruithof's rule revisited using LED illumination|journal=Journal of Modern Optics|date=20 July 2009|volume=56|issue=13|pages=1433–1446|doi=10.1080/09500340903151278|bibcode=2009JMOp...56.1433V |s2cid=121921684 }}</ref> Using [[Gas-discharge lamp|gas-discharge fluorescent lamps]], Kruithof was able to manipulate the color of emitted light and ask observers to report as to whether or not the source was pleasing to them. The sketch of his curve as presented consists of three major regions: the middle region, which corresponds to light sources considered pleasing; the lower region, which corresponds to colors that are considered cold and dim; and the upper region, which corresponds to colors that are warm and unnaturally colorful. These regions, while approximate, are still used to determine appropriate lighting configurations for homes or offices.