Wednesday, April 17, 2019

Relative Color Temperature

Anand has some questions about how people talk about color temperature.

He says he understands how a yellow can be cooler if it leans more toward blue, and warmer if it has a red bias. But which blue is warmer/ cooler? One could argue that a blue with a red or violet bias is warmer because red is a warm color. But a blue with a yellow or green bias can also be regarded as warmer because yellow is also a warm color.

He also asks which is warmer, green or magenta? And is there a pure primary color on the dividing line between warm and cool? Finally, Which is the warmest color on color wheel of tube colors yellow or orange?"

Casein paint
Answer: Artists mean different things when they talk of color as warm or cool. A swatch of orange or blue standing alone can be described in absolute terms as a warm color or a cool color. Alternately, some artists use color temperature more as a relative concept to distinguish two closely related colors. For example, a green mixed with more orange might be regarded as warmer than a similar green that was composed with more of a blue-green hue. 

As you suggest, this relative approach to assigning color temperature can be confusing when someone is talking about blue, which could be made warmer with the addition of either red or yellow. I would agree with you that blue is the coolest color, so I don't think it makes any sense to describe a warmer blue.

Is there a primary color on the dividing line between warm and cool? Yes, greens and violets are on the dividing line, but artists don't always agree precisely where to divide the color wheel. Color theory historian David Briggs explains further how the color wheel has been divided between warm and cool through history.  

Which color is the warmest? I'd say a yellow orange, like a cadmium yellow medium is the warmest. But this is also a matter of debate. Keep in mind that warmth is not something you can measure with a thermometer. It's psychological. And the effect of a color in a given painting depends to a great extent on what colors you put around it.


Garrett said...

I feel like the concept of warm and cool is something that is intuitive once you "get it", but can be very hard to explain in writing! I would also add that warmth and coolness is about more than just the pigment used, since the application of the paint impacts the relative warmth or coolness of a color. Transparent washes (on a light surface) tend to be very warm for instance. And any time you mix white into a pigment it tends to cool it.

When using blue and thinking about warm/cool, I would tend to imagine that the "grayer" or more neutral that I make the mixture, the warmer it will be. Also, certain pigments that would stand in for blue in certain cases (say ivory black mixed with some white), would appear quite "warm" compared to an ultramarine.

James Gurney said...

Garrett, those are important points, thanks for adding them. To say the same thing in different words, you can warm a pure blue (such as ultramarine) not only with red or yellow, but also with gray. And it's true that mixing white into a color, especially a warm color will cool it (and neutralize it) more than using that color transparently. As you say, these are phenomena that become clearer when you experiment with them.

David Briggs said...

Traditional colour theory has been in a pickle over these questions for a couple of centuries because it imagines that a greenish blue "contains yellow" and so can choose different blues as the coolest according to whether warmth is deemed to be associated primarily with red, yellow or both. Each of these positions has a long history (see my diagram 7.18 on and each has numerous ardent supporters today.

I think of the warm-cool idea as a precursor of the modern concept of hue opponency, in which the yellow-blue and red-green axes both have a relatively uncontroversial warm-cool association. So one could speak of yellow warmth and red warmth, and blue coolness and green coolness, although this just adds yet another position to the mix.

James Gurney said...

David, thanks for adding your voice to the conversation on this. For those who are interest in a deep dive into the theory and practice behind it, check out the link he gave, as well as his entire HueValueChroma website.

I see your point about how yellow-blue and red-green oppositions could each be framed as a warm vs. cool dimensions, and how theorists over time have split the color wheel into warm and cool quite differently. But doesn't recent perceptual science tell us that the yellow-blue opposition more basic perceptually, since the blue/yellow color receptors are far more ancient and primal? As I understand it, the ability to perceive the difference between yellow and blue is universal among all mammals, while the ability to distinguish red and green is a more recent development that, among mammals, we share only with primates?

CerverGirl said...
This comment has been removed by the author.
Rich said...

All that reminds me of

"Blue in Green"

a Miles Davis tune.
Miles Davis ventured into painting as well: resulting in kind of a "Cuban Kandinsky",

Which might open up another theme:
"Musician Painters".
Or: "Musicians painting away"?

CerverGirl said...

Your Color and Light book, Mr. Gurney, is so rich with lasting and helpful information on this subject--I love the gamuts you discuss in it--where a given temperature or light effect has a chosen range.

As a beginning painter, the conversation is wonderful since I am learning the values of different colors and their relationship next to one another creates such a diverse response to any viewer when on the surface.
I just learned my red and blue didn't make the purple I wanted, lol.
And how color temperature conveys mood or actual atmospheric temperature...
Then throw in how each color has an energy in my opinion, and it is my belief even the earth material which makes up different pigments have energy and, while we may not be able to measure it all that easily, it may in fact contribute to how warm or cool a color looks.

I reference your YouTube video doing the plein air painting in NYC, where you convey the yellow of a taxi cab without any yellow on your palette. Great talent and so much fun. Thank you for all of this.

David Briggs said...

Absolutely James, the blue-yellow axis can be considered the more basic scientifically in that it is older in evolutionary terms and also as you know aligns closely with the physical sunlight-skylight axis. On the other hand from discussions over the years with students and on forums my impression is that middle blue comes in a distant third to reddish blue (2nd) and greenish blue (1st) as the blue considered to be the coolest. No doubt a contributing factor to this is the prevalence of the infernal "split primary" idea, which requires that one blue bias be designated "warm" and the other "cool". Nevertheless the warm-cool polarity of the red-green axis seems quite widely accepted, and the subject is peoples' subjective associations after all.

Anand Jagdale said...

Dear James Gurney, Garrett, David Briggs, CerverGirl and Rich thanks to all for your invaluable inputs on color temperature and your tips will definitely be helpful while painting light effect and selecting colors.

I have been thinking over and over on color temperature concept and frankly hesitating while putting color on paper.

My first reaction after seeing a quick reply was; I was in awe and very joyful at the same time because now, I had a reply from famous celebrity artist. Sir I got your reply at my gmail account and also on your Blog, this is very touching in fact by seeing all the inputs from all artists and I admire your tender human nature.

I am living in India, Internet has brought the world closer but I think there must be someone on both ends who can reply.

Thanks a lot again and a lot of good wishes to all of you.

Don Ketchek said...

The problem with warm and cool is the unfortunate usual human desire to label and categorize thing absolutely. Success/Failure, Good/Bad - if you have one, there must be an opposite. Of course, more advanced minds understand that language doesn't always represent reality in such a way and that there are "shades of gray" so to speak, and things can be "relative" to something else. In teaching about warm and cool colors myself, I have always tried to stress that there is no dividing line - that it is a matter of degree. Ans also, since we are talking about perception, things are perceived differently by each person. If one sees yellow or orange as the warmest and blue as the coolest, then it is easy to imagine all colors getting cooler as they move from yellow/orange towards blue. That some line is crossed separating warm and cool seems silly once one understands that all colors shift gradually from one to another.

I have always been confused by the desire to "define" a warm and cool blue. As I see it all blues are cool and any slight deviation either towards green or towards red matters little or not at all. One rarely sees the same confusion or desire to label a warm or cool orange. They are all warm and no one seems to mind that!