Why is Kelvin color temp on digital cameras the opposite of what it is in actuality?

[ak_]

This has always baffled me: we know that low kelvin temperatures (eg 3000) look warm, and high kelvin values (eg 7000) look cool right?

So why on cameras are they reversed, and if you dial-in say 3000k the picture is made cooler?

 

[ak_]

..I'm not asking 'why is kelvin warm/cold the way it is' - i know its based on the color of a flame where blue is hotter than orange/red. I'm asking why on digital cameras is an input value of say 3000 actually making the image look cooler rather than warmer?

 

[chuasam]

Because setting it at 3000°K cools the image so that a warm image looks cooler.

 

[ak_]

Because setting it at 3000°K cools the image so that a warm image looks cooler.

A warm image is already at say 3000k and also cool is much higher kelvin (say 7000 or higher). If i want to cool the temperature I would dial in a higher value (raise the kelvin) not a lower (warmer) value. I'm trying right now (and have on various cameras before). My WB is at 4000k. I just raised it 10000k and the live view image has gotten much warmer. That's the opposite of what it should do. To cool it to something that looks real, I've just had to reduce it down back down to 3600k (from 10000). 10000k should be very cool/blue, but it's the opposite.

 

[Alexr25]

The white balance temperature you dial in is the color temperature of the scene illumination not the color temperature balance that you want in the final image. The camera manufacturers assumption is that if color temperature is critical to your work you would use a meter to measure the illumination color temperature and dial that value into the camera and that would produce the correct color balance in the final image.

 

[atiqursumon]

I think 7000 is enough

 

[DjMeinhardt]

It's simple. Say you took a picture of a pure white building and the camera estimated the light falling on the building at a high Kelvin of say 7000. As you said, a high Kelvin temp looks "cool," so the camera thought the light was very "cool" and made the building look warmer to compensate. However, if you say the light was ACTUALLY 3000 (by "dialing" in the temp) the software "removes" that compensation and renders the scene as it would look to your eye in 3000 degree light, which would be cooler than it did when it thought the temp was 7000.

Human vision does this automatically (it's called color constancy), in a range of Kelvin. Scenes only look really warm to us when the Kelvin gets very very low (like at sunset). The camera cannot do as good of a job, so the best solution is to tell it what the temp was (e.g., use a gray card). Now, at sunset, you probably would not WANT to dial in the low Kelvin, because it will make white objects look white (i.e., cooler) and not like our eyes see them at sunset (i.e., warm). Balancing the color with a gray card at sunset gives you non-sunset-like results.

 

[snowbear]

The white balance temperature you dial in is the color temperature of the scene illumination not the color temperature balance that you want in the final image. The camera manufacturers assumption is that if color temperature is critical to your work you would use a meter to measure the illumination color temperature and dial that value into the camera and that would produce the correct color balance in the final image.

^
This. The setting is for the scene.

If the scene is 5000K and you set the camera for 3000K, that means the scene is now 2000K cooler (higher) than the white balance - it's going to look cool-shifted.

 

[Designer]

So why on cameras are they reversed, and if you dial-in say 3000k the picture is made cooler?

Because your camera is not making the light, you are adjusting the WB to react to the light. Think of it as something akin to; on a bright sunny day, you put your sunglasses on before you step outside. So you are setting the WB to counter the color temp of the light before the exposure. To verify this, set the WB opposite of what you would do to yield a "normal" color rendering and see what happens. Your camera will record the existing color temperature in the extreme.

 

[BananaRepublic]

OP, the sun is bright e.g. warm, in Kelvin the light (radiation) coming from the Sun, and other similar stars, is about 5500 degrees Kelvin the background radiation temperature of the universe is 3000 ,approx, degrees kelvin. the fella who said the light hitting a building might be 7000 k has no clue what you're actual question was.

There is some backwardness like you said when it comes to cameras WB settings and actually science, which I don't understand myself but the above is the actual science as far as the universe in concerned.

In General when you ask a question like that or indeed an any sort of open ended question on hear you get a lot of garbage in response bare that in mind.

 

[KmH]

The background radiation color temperature of the universe is 2.7260±0.0013 K, just above absolute zero K.

 

[BananaRepublic]

The background radiation color temperature of the universe is 2.7260±0.0013 K, just above absolute zero K.

He asked for an answer not some more baffling crap.

 

[DjMeinhardt]

When I first starting shooting raw I had the exact same question, and got it sorted out, so I think I know what the OP was asking. Light comes in different temperatures, and thus changes how a scene appears to a camera. Our eyes/brain adjust for many of these, keeping white things white under different temps (colors) of light. Anyone who ever shot with film knows that using daylight calibrated film indoors (under incandescent light) gave you pictures with a distinct yellow cast, even though the scene did not look yellow to our eyes. By changing the setting in imaging software you can compensate for this. For example, you'll get a yellow cast shooting under incandescent light with the camera set at daylight (5500 K). By changing the setting to 3000, the yellow cast will be removed, giving you a "cooler" image that more accurately reflects the way our eyes see the scene.

Some typical color temperatures are:

1500 K Candlelight
2680 K 40 W incandescent lamp
3000 K 200 W incandescent lamp
3200 K Sunrise/sunset
3400 K Tungsten lamp
3400 K 1 hour from dusk/dawn
5000-4500 K Xenon lamp/light arc
5500 K Sunny daylight around noon
5500-5600 K Electronic photo flash
6500-7500 K Overcast sky
9000-12000 K Blue sky

 

[Alexr25]

OP, the sun is bright e.g. warm, in Kelvin the light (radiation) coming from the Sun, and other similar stars, is about 5500 degrees Kelvin the background radiation temperature of the universe is 3000 ,approx, degrees kelvin.

Actually the background temperature of the universe is about 3 degrees Kelvin.

the fella who said the light hitting a building might be 7000 k has no clue what you're actual question was.

The color temperature of an overcast sky is about 7000 degrees K so there is nothing improbable in that.

In General when you ask a question like that or indeed an any sort of open ended question on hear you get a lot of garbage in response

And finally something we can agree on!

 

[WayneF]

This has always baffled me: we know that low kelvin temperatures (eg 3000) look warm, and high kelvin values (eg 7000) look cool right?

So why on cameras are they reversed, and if you dial-in say 3000k the picture is made cooler?

Everyone is right, it is not reversed, blue is hotter than red.

You are thinking of the artists concept of color, maybe about red fire being hot, and blue ice and water being cool, but the engineers think of color temperature as incandescent heat, like heating metal, where heating it turns red hot first, then orange and yellow, and then white and blue, etc. Our Sun for example, around 5000K light, which we call white and midrange.

http://www.webexhibits.org/causesofcolor/3.html

Interesting (to me) is the color of our flashes (not incandescent, but instead ionized xenon gas, but color temperature is still measured in the incandescent fashion).

Studio monolights simply turn their voltage down to implement lower power level. This lower voltage is less energetic, and becomes cooler, more red at low power.

Our speedights are always at full voltage, but they implement lower power level by cutting off the flash tube current when the light is sufficient. This cuts off the final low trailing tail as it fades away, which is the cool red part, therefore the remaining flash used is less red (the hotter full peak).