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News Story on LED Streetlights in Philadelphia

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#1 earlyriser



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Posted 13 April 2018 - 06:11 AM

News story on Philadelphia's plans for replacing streetlights with LED. 




From the article:


"The Streets deputy commissioner said 4000K LEDs does not make the streets safer per se, but it allows them to recognize faces and colors when using surveillance cameras. With a conventional 2700K high-pressure sodium light or a 3000K LED light they can’t tell the color of the shirt of a suspect in a video, whereas, with a 4000K they can, he explained."


I'm curious about the contention that 3000K LED lights don't show color well. I have these in my house, and they seem to render colors at least as well as incandescent lights, which are much better than high pressure sodium lights. I think people look at the CCT rating and think that 3000K must be similar to HPS lights, which is incorrect.


I emailed the reporter to let her know I enjoyed her article and to point out how the commissioner's statement is in conflict with my experience with 3000K LED lights. Maybe she'll ask the commissioner about this next time around.

Edited by earlyriser, 13 April 2018 - 06:23 AM.

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#2 HarryRik9


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Posted 13 April 2018 - 06:42 AM

The new LED lights do not emit spectral lines so make filters less effective. 

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#3 skidaddy


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Posted 15 April 2018 - 10:57 AM

Perhaps they should ban hoodies, baseball caps, and sunglasses like they do in banks. Some what of flip response but it goes to the governmental thinking that all this mostly useless light in addition to direct costs comes also comes with an environmental degradation for dubious benefit. 

Edited by skidaddy, 15 April 2018 - 02:16 PM.

#4 WoodyEnd


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Posted 16 April 2018 - 02:18 PM

I tried some 4000K LED bulbs at home and found that they appeared pretty much monochromatic. The intense blue washed out all the colors. 3000K lights are closer to sunlight.  Apparently the interests of the police state are the only ones that count.

#5 Tonk



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Posted 23 April 2018 - 10:54 AM

There is a difference between visual perception of colour under various colour temperature lighting compared to a camera. However this can be rectified by altering the white balance response of the camera (but i bet the cameras they use are set for daylight WB and maybe cant be adjusted). Human eye\brain does auto white balance

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