Wednesday, September 3, 2014

Is an "yellow" traffic light yellow?

Once common disagreement in my household is what color is the "slow down yellow" light between red and green (or in Utah the "speed up" light)?  I always said it was orange.  Some people call it amber.  Yellow is what the cop usually calls it as he or she is writing your ticket.   But since writing that glue/green post I have become very aware of teals around my environment and I swear the "green light" is teal.  A quick web search revealed that LEDs have not surprisingly taken over the traffic light industry, and every buying government has its own spec.  There probably is a converging standard, but my quick search didn't find it.  And these LED lights are probably NOT the same as what I've been looking at all these years.  So I took a picture near my house and by eye calibrated it so it looks "right" when at the scene.  Obviously not scientific, and just my streetlights. 

Here they are (note the awesome aliasing from the too many megapixels trend... ironic that video games can finally render wires but cameras finally can't!):

Blurring and grabbing the center of the blurred light yields:

I thought about mining the xkcd data to see what people call these and them and realized I was too lazy to do that.  But before giving up I made one last google and found this awesome visualization.  My read from that is pretty good names for the above colors are "turquoise",  "salmon", and "magenta".  Of course context is important, and as red, yellow, and green are highly salient primary colors so I think sticking with "green", "yellow", and "red" makes things less confusing.  And note how complex the interaction of names and colors can be, check out this discussion that leads with blue Japanese traffic lights.

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