Question on color temperature

jimojimo

Hi all,
This is likely a dumb question...but I've read countless times that, in regards to white-balance, the color temperature follows what color a heated piece of steel would get:
It starts reddish orange, but then as it gets hotter it gets bluer, then white at its hottest.

However, in my raw software (bibble), if you have, say an indoors photo in warm tungsten lighting and you want to 'cool' it, you make it bluer, which is (I thought) hotter. But the WB guage shows the cooler, blue temps as lower--around 2200 Kelvin, and to 'warm up' a blueish hued image to a tungsten hue you go up in temperature to 5000-6000 Kelvin..but I thought the orange was cooler than blue...at least in terms of the analogy I had read which seems to have just confused me.

So I guess my question is, what part of the original 'bluer is hotter' analogy I had read did I misunderstand? This is one of those minor things that's bugged me too much for probably too long...

Thanks very much,
--Jim

jjbong

jimojimo wrote:

Hi all,
This is likely a dumb question...
--Jim

Not at all.

Here we're talking about two different things. One is science and one is emotional response.

Scientifically, blue is warmer than yellow, in the sense that when you heat materials to extremes, they'll get yellow as they heat up and then get blue as they get hotter. Blue-white stars, for example, are much hotter than yellow stars. I'm simplifying greatly here. So color temperature follows this, with higher temperatures going towards blue, and lower going towards yellow.

This has nothing to do with our emotional response to a photo. When we look at a picture, we think of yellow as warmer than blue (and magenta as warmer than green, to include the other axis of color). Our reaction to an image as warm or cold has nothing to do with the science behind color temperature. Perversely, it happens to be opposed to it (and I use "happens" advisedly, as there's really no connection between the science and the emotional response). So if the only handle we had were adjusting the color temperature of an image, we would warm it up by making the color temperature colder.

jfriend

A worthy and relevant reference article: http://en.wikipedia.org/wiki/Color_temperature.

I think you've got the steel colors backwards. Reddish-orange is hotter than blue which aligns with the "white balance" tools we see in our photo editors.

Here's a chart of steel color by temperature: http://www.muggyweld.com/color.html (isn't it amazing what you can find on Google). And another: http://www.threeplanes.net/toolsteel.html.

jimojimo

John and John,
Thanks both very much, I'm glad it wasn't just me...the wiki article goes on to say:

<<Counterintuitively, higher Kelvin temperatures (3600–5500 K) are "cool" (green–blue) colors, and lower color temperatures (2700–3000 K) "warm" (yellow–red) colors. >>

--Jim