Selective yellow

Colour

Both the internationalized European ECE Regulation 19 and North American SAE standard J583 permit selective yellow front fog lamps. Meanwhile, ECE Regulation 48 (enforced 08 October 2016) requires new vehicles to be equipped with headlamps emitting white light. However, selective yellow headlamps remain permitted throughout Europe on vehicles already so equipped, as well as in non-European locales, such as Japan and New Zealand.

The intent of selective yellow is to improve vision by removing short, blue to violet wavelengths from the projected light. These wavelengths are difficult for the human visual system to process properly, and they cause perceived dazzle and glare effects in rain, fog and snow. Removing the blue-violet portion of a lamp's output to obtain selective yellow light can entail filter losses of around 15%,{{cite report

A research experiment done in the UK in 1968 using tungsten (non-halogen) lamps found that visual acuity is about 3% better with selective yellow headlamps than with white ones of equal intensity.{{cite report |archive-url=https://web.archive.org/web/20180729230449/https://trl.co.uk/sites/default/files/LR156.pdf |archive-date=2018-07-29 | access-date = 29 July 2018 | access-date = 29 July 2018

Formal definition

The UNECE Regulations formally define selective yellow in terms of the CIE 1931 colour space as follows:

For front fog lamps, the limit towards white is extended:

The entirety of the basic selective yellow definition lies outside the gamut of the sRGB colour space—such a pure yellow cannot be represented using RGB primaries. The colour swatch above is a desaturated approximation, created by taking the centroid of the standard selective yellow definition at (0.502, 0.477) and moving it towards the D65 white point, until it meets the sRGB gamut triangle at (0.478, 0.458).

File:Porsche_911_with_selective_yellow_headlights.jpg|Porsche 911 with selective yellow lights File:foglights.jpg|Selective yellow foglights File:fogson.jpg|The beam produced by selective yellow lights

References

References

1. [http://www.unece.org/fileadmin/DAM/trans/doc/2005/wp29gre/TRANS-WP29-GRE-2005-04e.pdf UNECE]
2. [http://www.unece.org/trans/main/wp29/wp29regs/r019r5e.pdf ECE Regulation 19: Uniform Provisions Concerning the Approval of Power-Driven Vehicle Front Fog Lamps]
3. [http://standards.sae.org/j583_200509 SAE Standard J583: Front Fog Lamp]
4. [https://op.europa.eu/en/publication-detail/-/publication/192086c4-870f-11e6-b076-01aa75ed71a1/language-en ECE Regulation 48: Uniform Provisions Concerning the Approval of Vehicles with Regard to the Installation of Lighting and Light-Signalling Devices]
5. [http://retail.ihs.com/abstracts/jsa/jis-d-5500.jsp Japanese Industrial Standard JIS D-5500] {{webarchive. link. (2007-08-15 ''Automobile Parts--Lighting and Light Signaling Devices'' p. 5, sec. 4.4.2, table #4)
6. [https://web.archive.org/web/20140831152201/http://vehicleinspection.nzta.govt.nz/virms/in-service-wof-and-cof/general/lighting/headlamps New Zealand Vehicle Inspection Requirement Manual p. 4.1.2]
7. Bullough, John. (2001). "Driving in Snow: Effect of Headlamp Color at Mesopic and Photopic Light Levels". SAE Technical Paper Series.